Next Article in Journal
Mechanochemistry in Waste Valorization: Advances in the Synthesis of Catalysts, Polymers, and Functional Materials
Previous Article in Journal
Advances in Composite Photocatalysts for Efficient Degradation of Organic Pollutants: Strategies, Challenges, and Future Perspectives
Previous Article in Special Issue
Iron-Doped NiSe2 and Its Enhanced Oxygen Evolution Reaction Activity
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
Catalysts
Volume 15
Issue 9
10.3390/catal15090895
catalysts-logo
Submit to this Journal Review for this Journal Propose a Special Issue
► Article Menu

Article Menu

share Share announcement Help format_quote Cite question_answer Discuss in SciProfiles
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Article

Enhanced Oxygen Reduction Reaction Activity of Carbon-Supported Pt-Co Catalysts Prepared by Electroless Deposition and Galvanic Replacement

by
Angeliki Banti
1,
Ivalina Avramova
2,
Sotiris Sotiropoulos
1 and
Jenia Georgieva
3,*
1
Department of Chemistry, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
2
Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria
3
Rostislaw Kaischew Institute of Physical Chemistry, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria
*
Author to whom correspondence should be addressed.
Catalysts 2025, 15(9), 895; https://doi.org/10.3390/catal15090895
Submission received: 30 July 2025 / Revised: 29 August 2025 / Accepted: 29 August 2025 / Published: 17 September 2025
Browse Figures
Versions Notes

Abstract

The development of effective catalysts for the oxygen reduction reaction (ORR) is crucial for improving the performance of fuel cells. Efficient carbon-supported Pt-Co nanocatalysts were successfully prepared by a generic two-step method: (i) electroless deposition of a Co-P coating on Vulcan XC72R carbon powder and (ii) subsequent spontaneous partial galvanic replacement of Co by Pt, upon immersion of the Co/C precursor in a chloroplatinate solution. The prepared Pt-Co particles (of a core-shell structure) are dispersed on a Vulcan XC-72 support, forming agglomerates made of nanoparticles smaller than 10 nm. The composition and surface morphology of the samples were characterized by scanning electron microscopy and energy-dispersive X-ray spectroscopy (SEM/EDS) as well as transmission electron microscopy (TEM). The crystal structures of the Co-P/C precursor and Pt-Co/C catalyst were investigated by X-ray diffraction (XRD). XPS analysis was performed to study the chemical state of the surface layers of the precursor and catalyst. The electrochemical behavior of the Pt-Co/C composites was evaluated by cyclic voltammetry (CV). Linear sweep voltammetry (LSV) experiments were used to assess the catalytic activity towards the ORR and compared with that of a commercial Pt/C catalyst. The Pt-Co/C catalysts exhibit mass-specific and surface-specific activities (of jm = 133 mA mg−1 and jesa = 0.661 mA cm−2, respectively) at a typical overpotential value of 380 mV (+0.85 V vs. RHE); these are superior to those of similar electrodes made of a commercial Pt/C catalyst (jm = 50.6 mA mg−1; jesa = 0.165 mA cm−2). The beneficial effect of even small (<1% wt.%) quantities of Co in the catalyst on Pt ORR activity may be attributed to an optimum catalyst composition and particle size resulting from the proposed preparation method.

Graphical Abstract

1. Introduction

Polymer electrolyte membrane fuel cells (PEMFCs) are promising alternatives to fossil fuels due to their high energy efficiency and low emissions [1,2,3]. However, their widespread commercialization is still limited by the sluggish electroreduction of molecular oxygen to water at the cathode side [4,5]. It is believed that the reason for the slow ORR kinetics is due to the quite strong Pt-O surface bond [6]. Carbon-supported Pt is considered to be the most common and efficient catalyst for accelerating the ORR in acidic environments at the present stage [7,8]. However, because these materials require a high loading of expensive Pt, the major challenges receiving particular attention are to develop either non-platinum group metal (PGM) catalysts or alternative Pt-based catalysts with higher ORR activity at lower Pt loading values [9,10,11,12,13].
One of the strategies has focused on enhancing the surface area-based activity as well as the Pt mass-based activity of Pt by alloying it with 3d transition metals (M) such as Cu [14,15], Co [15,16,17,18,19,20,21], Ni [15,20], etc. One has to distinguish between supported alloys and non-alloyed multi-component systems [22] since in many supported catalysts reported in literature, the metals were only partially alloyed. Moreover, in the case of an alloy, one should further distinguish between a solid solution (disordered alloy) and an intermetallic compound (ordered alloy). The improved catalytic activity of these Pt-M bimetallic systems can be explained by two effects. One is the geometric effect, which refers to the change of the Pt-Pt bond distance, and the other is the electronic effect due to a modification of the d-band center of Pt by transition metals [6,20]. Among the various Pt-M alloys, Pt-Co alloy catalysts have received much attention for use as cathode layers in PEMFCs, because of their favorable ORR activity and supposed corrosion stability. The microstructure of the Pt-Co alloy bimetallic systems can be regulated to form ordered Pt-Co compounds and disordered Pt-CoOx alloy catalysts [19,21,22,23,24,25]. Recently, it has been reported that PtxCo1−x core-shell catalysts have improved ORR activity due to the existence of a particle core, where Co is not only in its metallic state but also as 40–60% of Co oxide [22]. The Co oxide species are very likely the result of the activation process by electrochemical de-alloying of the precursor. However, the positive effect of the Co oxide on the ORR activity is not fully understood. Another unresolved problem is the inevitable dissolution of the transition metals during the fuel cell operation (especially at high concentrations), resulting in a gradual decrease of catalytic activity. Subsequently, the dissolved metal ions can displace the protons in the Nafion® membrane and ionomer, reducing their proton conductivity [19]. The main factors influencing the catalytic activity of binary alloys are the dispersion and the compositional homogeneity of the alloy clusters, the amount of the added transition metal, its tendency to form an alloy with Pt, as well as the catalyst support [25,26].
Most of the mentioned factors are influenced by the method of catalyst preparation and experimental conditions. Generally, metal fuel cell catalysts are obtained using energy-consuming high-temperature methods, hazardous reducing agents and relatively concentrated solutions of precious metal ions [25]. In recent years, an alternative method for the preparation of the bimetallic supported systems has been developed. The method is based on the spontaneous galvanic replacement of surface layers of a non-noble metal M (M: Pb, Cu, Fe, Co, Ni) by immersion of the former in a solution of the more noble metal ions (e.g., Pt, Au, Pd), which is due to the difference in the standard reduction potentials of the two metals. This procedure was first applied by Adzic and co-workers to underpotentially deposited (UPD) Cu monolayers [27] and Cu and Pb bulk deposits by Kokkinidis and co-workers [28,29]. The method was subsequently developed for other transition metals (Fe, Co, Ni) and substrates (glassy carbon, C powders) [14,29,30,31,32,33,34,35,36]. Advantages of this alternative technique are its room-temperature conditions and that the formed precious metal shell results in a low loading and can also protect the less noble metal core from corrosion. Also, as it involves a simple heterogeneous/surface reaction it may easily be scaled up simply by increasing both the catalyst support quantity-surface area and the solution volume, so as to keep the surface-to-volume constant, as a few hundred milliliters of solution are typically needed for the production of a few hundred milligrams of catalyst (the range of the quantity required for the fabrication of fuel cell electrodes), scaling up to a few grams is envisaged to be feasible. The obtained results for this type of Pt(M) or Pt(M)/C catalysts (where M had been deposited by electroless plating or electrodeposition on C) have shown enhanced catalytic activity towards the methanol oxidation reaction (MOR) and ORR. In our first publications of this series, the precursor Cu/C material used for the synthesis of Pt(Cu)/C catalysts was obtained by simple chemical reduction of Cu salts by NaBH4 onto C powder [14,34]. This procedure leads to the formation of large Cu particles (usually tens of nm large). It was also found that, during the subsequent galvanic replacement step, a large Cu loss (up to ca 72%) occurs. This is most likely a consequence of the dissolution of Cu that has not been platinized or contained in Pt(Cu) particles of loose adherence. Following the search for an alternative method for the non-noble metal M precursor preparation, we have published results showing the advantages of electroless methods for more homogeneous distribution of the precursor M nanoparticles in the 2–5 nm diameter range, also characterized by stronger adherence to carbon. The two-step electroless deposition-galvanic replacement technique produced Pt-Ni/C [33] and Pt-Cu/C [35] efficient catalysts with more pronounced intrinsic and mass-specific catalytic activity towards MOR when compared to the commercial Pt/C catalyst. To our knowledge, there are no data in the literature showing that this method has been used to prepare high-surface-area carbon-supported Pt-Co catalysts for ORR.
The aim of the work presented here has been to establish the possibility of using this alternative two-step procedure to obtain a Pt-Co/C material and to study ORR at the resulting catalyst. In this regard, specific objectives have been: (i) the physicochemical characterization of the morphology, composition, structure and electronic state of the components by TEM, SEM/EDS, XRD, and XPS and (ii) the electrochemical characterization of the material using CV and LSV at a rotating disc electrode (RDE), to assess the catalytic activity towards the ORR and compare it with that of a commercial Pt/C catalyst.

2. Results and Discussion

2.1. Physicochemical Characterization

The large area (317 μm × 259 μm) EDS analysis of the prepared Co-P/C and Pt-Co/C composites (Table 1) showed that after galvanic replacement, the amount of Co dramatically decreases (from 24 wt.% to 0.7 wt.%) and P originating from the electroless plating bath completely disappears. For the Pt-Co/C catalyst, the EDS analysis shows a content of approximately 17 wt.% Pt (Table 1). These correspond to a 7 ÷ 1 Pt-to-Co atomic composition ratio (lower than the typical 3 ÷ 1 of similar catalysts reported in the literature [21,22,23,24,25,26].
The TEM micrographs of Co-P/C and Pt-Co/C powder materials and the corresponding histogram, presented in Figure 1a–c, reveal that after galvanic replacement, the catalyst consists mainly of large aggregates/clusters and fewer particles smaller than 10 nm (ranging mainly from 1.2–4.4 nm in diameter). The histogram, shown in Figure 1c, was determined by segmentation of the right half of Figure 1b and 2D individual object analysis both performed by computer tomography analysis software CtAn, version 1.7 by Bruker. Although this morphology is expected to lead to a decrease in electroactive surface area (when compared to typical supported catalysts, made of 2–3 nm particles—see for example [33]), the presence of Co (encapsulated in Pt shell aggregates—see also the EDS spot analysis and XPS results below) may increase the catalyst’s inherent ORR activity. This structural configuration may limit the exposure of active sites but could still potentially enhance the catalyst’s surface area and catalytic activity due to the larger platinum surface area.
Figure 2 presents the results from TEM-EDS spot chemical analyses, made in different areas of large catalyst aggregates, together with the corresponding elemental mapping. The obtained spectra show the presence of Co in all aggregates in low quantities, in line with most of it being dissolved during the galvanic replacement process and only small quantities residing in the core of these particles. A Pt:Co atom ratio from 15:1 to 36:1 was obtained, depending on the analyzed aggregate; the fact that these values are larger than the one obtained from large area analysis (probing both large agglomerates and isolated nanoparticles) indicates that smaller particles may have a larger Co core content.
The diffractogram of the Co-P/C precursor (Figure 3a) contains a large amount of amorphous phase, and therefore, the presence of a strong background is seen. The presence of several phases is distinguished: hexagonal metallic Co, Co(OH)2, and a small amount of CoO. The results are as expected, considering the alkaline conditions of electroless deposition of the precursor Co-P alloys on the C support.
Following galvanic replacement, the peaks of metallic Pt were detected at 40.24°, 46.53°, 68.32°, and 82.14° (Figure 3b). Very close to these positions, 2θ also corresponds to the peaks of the intermetallic alloy cobalt platinum (1/3)—Disordered Reference code: 98-010-7047. For this reason, it is difficult to determine unambiguously the composition using XRD. However, from the TEM-EDS spot chemical analyses (presented above), the insertion of a certain amount of Co into the Pt lattice (up to about 1 at.%) can be assumed. In addition, the presence of diffraction peaks of CoOOH was also registered. Most likely, during the galvanic replacement process, the metallic Co and CoO dissolve preferentially, causing platinum deposition and the formation of a Pt shell. Simultaneously, the initially formed Co(OH)2 is partially oxidized, and Co passes into the +3 oxidation state to CoOOH. From the diffractogram, it is difficult to determine whether there is only CoOOH or a mixture of Co(OH)2 and a predominant amount of CoOOH. In Ref. [37], the authors found that the energy difference between CoOOH and Co(OH)2 was 0.6 eV, and that the activation energy from CoOOH to Co(OH)2 was higher than for the opposite process, indicating that the mixed phase is more stable than pure Co(OH)2. Literature data also indicate that PtxCo1−x core-shell catalysts have improved ORR activity due to the existence of a particle core, where Co is not only in the metallic state but also as 40–60% of Co oxide [22].
The surface composition and chemical states of Pt-Co/C were characterized by XPS. The obtained results are shown in Figure 4a–d.
The C 1s and O 1s in Figure 4a,b are typical for carbon and oxygen, having binding energies at 284.6 eV and 532.1 eV, respectively, with typical shapes. The two pairs of peaks after deconvolution of the Pt 4f peak (Figure 4c) indicate the existence of two different Pt oxidation states on the surface. The first peaks of Pt 4f7/2 at 71.6 eV and Pt 4f5/2 at 74.9 eV originated from the 66.2% metallic Pt(0), while the peaks of Pt 4f7/2 at 73.1 eV and Pt 4f5/2 at 76.5 eV are attributed to the Pt(II) chemical state (33.8%) on PtO or Pt(OH)2 [38]. The evaluated surface concentrations are as follows: C 1s—95.4 at.%, O 1s—4.1 at.% and Pt 4f—0.5 at.%.
Co could not be detected on the surface (Figure 4d). It is possible that the Co content is below the sensitivity of XPS analysis at a depth of 3–5 nm or is covered by Pt, which is in agreement with the results of the above XRD analyses. These findings, together with the detection of Co by EDS spot analysis of catalyst aggregates, indicate that Co resides in the core of the particles.

2.2. Electrochemical Characterization

Figure 5 shows cyclic voltammetric curves of Pt-Co/C and commercial Pt/C catalysts cast on a GC RDE, recorded at 200 mV s−1 in deaerated 0.1 M HClO4. No significant change in the voltammetric picture between the first and subsequent cycles was observed, indicating the absence of exposed Co, in line with XPS measurements detecting no Co on the surface. Although the obtained voltammograms are slightly obscured due to the high capacitive currents of the large surface area C support, it can still be concluded that H adsorption/desorption and oxide formation/desorption (characteristic of the surface electrochemistry of Pt) are present. The fact that the capacitive/pseudo-capacitive current associated with the double-layer region/carbon surface electrochemistry (+0.40–+0.80 V vs. RHE during the anodic scan) is higher in the case of the PtCo/C electrode is in line with the existence of large PtCo aggregates; these result in a lower coverage of the C support, which in turn increases its contribution to the capacitive/pseudo-capacitive currents.
From the area below the H desorption peaks (0.00–+0.40 vs. RHE potential range), the electroactive surface area of Pt can be calculated (taking into account the charge density of 210 μC cm−2 corresponding to the formation of a full H monolayer); this translates into a Pt mass-specific surface area of 19 m2 g−1 for the generic Pt-Co/C catalyst and 31 m2 g−1 for the Pt/C industrial catalyst. These values are lower than those usually reported for similar catalysts (50–100 m2 g−1) [21,23] and are more likely due to the particular type of film used in this work. The specific conditions of film composition and its preparation methods are well-known to affect catalyst accessibility and/or catalyst aggregation and consequently its electrochemical behavior [39]; hence, all results of similar studies should refer to an internal standard (in this case, the voltammetry of electrodes made of commercial 20 wt.% Pt/C catalyst and 30 wt.% Nafion®) prepared under identical conditions.
To assess the activity of the catalysts towards ORR in acid, LSV experiments were performed from +1.10 V to +0.00 V vs. RHE in oxygen-saturated 0.1 M HClO4 (pH ≈ 1). Figure 6 shows the obtained curves for the Pt-Co/C catalyst, presenting the current density vs. applied potential, corrected for the uncompensated resistance. The LSV curves, shown in Figure 6a were recorded at 20 mV s−1 in an oxygen-saturated 0.1 M HClO4 solution, at different electrode rotation speeds (in the range of 100–2500 rpm). The Figure 6b presents the corresponding Koutecky–Levich plot (1/I1/2 vs. 1/f1/2) of the related equation:
1 I = 1 I k + 1 B ω 1 / 2
with
Β = 0.62 n F A D O 2 2 / 3 ν − 1 / 6 C O 2
Using for the O2 diffusion coefficient, DO2, the value of 1.90 × 10−5 cm2 s−1, for the concentration of dissolved O2 in the bulk solution, CO2, 1.22 × 10−6 M and for the kinematic viscosity of the solution, v, 0.011 cm2 s−1 [40] one can confirm a number of 4e− associated with ORR at Pt.
Figure 7 shows polarization curves of Pt-Co/C and Pt/C catalysts (of the same Pt loading of ca 0.05 mg cm−2) for ORR at 1600 rpm, with the current normalized by the geometric area (Figure 7a) and by platinum mass (Figure 7b). The Pt-Co/C nanomaterial demonstrates a lower onset potential than that of the Pt/C catalyst, indicating higher ORR activity overall. This enhanced performance suggests that the approximate 7:1 Pt:Co atomic ratio and the structure of Pt-Co/C provide favorable catalytic properties, which, despite its lower electroactive surface area, enable this generic catalyst to surpass the activity of the commercial standard catalyst.
From the Tafel plots for Pt-Co and Pt catalysts supported on Vulcan XC 72 - log (current density per electroactive surface area, jk, esa) versus E from 1.00 V to 0.80 V vs. RHE, we obtained similar Tafel slope values for both catalysts, with 66 mV/dec for Pt/C and 75 mV/dec for Pt-Co/C (Figure 8). This suggests that the ORR is primarily controlled by the chemisorption of oxygen and the transfer of the first electron and that Co does not change the mechanism (but it may change the activity within the same mechanism).
These values are consistent with the literature for low-to-medium overpotential ranges. Also, although Pt-Co catalysts exhibit large aggregates and relatively low surface area, their intrinsic catalytic activity (current density per electroactive surface area) appears to be higher than that of the commercial catalyst, and this seems to determine their better performance in ORR overall. This enhanced activity highlights the favorable catalytic properties of Pt-Co materials for oxygen reduction applications. This is in line with what is reported for other Pt skin–M core (transition metal) catalytic systems (such as Ni, Ti, V, Fe—see for example [20], or Cu—see for example [41]).
Table 2 provides a comparison of the catalytic performance of Pt-Co prepared in our lab and a commercial/internal standard Pt catalyst on Vulcan C support, at two different overpotentials, at η = 330 mV and η = 380 mV. At η = 330 mV, the Pt/C catalyst shows a mass-specific activity of 9.93 mA mg−1 and a surface-specific activity of 0.032 mA cm−2. The Pt-Co/C catalyst exhibits higher mass-specific and surface-specific activities of 36.6 mA mg−1 and 0.182 mA cm−2, respectively. At η = 380 mV, the Pt/C catalyst displays an activity of 50.6 mA mg−1 and 0.165 mA cm−2, respectively, while the Pt-Co/C achieves a mass-specific activity of 133 mA mg−1 and a surface-specific activity of 0.661 mA cm−2. These results suggest that the Pt-Co catalyst achieves superior ORR performance compared to the Pt-only catalyst at both overpotentials. This highlights the beneficial effect of Co addition (even at low quantities) in enhancing the catalytic activity for oxygen reduction.
Finally, a comparison of the performance of the catalysts of this work with other Pt-Co/C-supported powder catalysts that have appeared in the literature has been attempted and shown in Table 3 below. As the actual current density values for ORR determined by linear voltammetry at film electrodes largely depend on film preparation, potential scan rate and initial potential, a more appropriate comparison descriptor is the enhancement factor, with respect to a Pt/C internal standard in each study.
It can be seen that the low-energy and chemistry-intensive preparation method proposed in this work compares well with other Pt-Co ORR catalysts (despite containing significantly less Co, which is expected to increase catalyst stability).

3. Experimental

3.1. Synthesis of Pt-Co/C Catalyst

An oxidative pretreatment of carbon powder (Vulcan XC-72) was done by immersing 0.25 g in a 100 mL solution of 1.0 M H2SO4 (Sigma-Aldrich, ACS reagent, Merck Bulgaria EAD) and 10 g (NH4)2S2O8 (Sigma-Aldrich, ACS reagent, Merck Bulgaria EAD) [50]. The suspension was stirred in an ultrasonic bath for 30 min and another 8 h using a magnetic stirrer at room temperature. The precipitate was filtered, rinsed with deionized H2O to neutral pH and left to dry in air. A total of 0.125 g of the oxidized carbon was mechanically ground in a mortar and suspended in 50 mL of 0.1 M HCl (Sigma-Aldrich, ACS reagent, Merck Bulgaria EAD) and 10−3 M PdCl2 (anhydrous, 59% Pd) for activation. The process was performed for 30 min under magnetic stirring to ensure palladium ion adsorption on the carbon surface. Then, the suspension was filtered, and the precipitate was rinsed with H2O and left to dry. Then, a two-step catalyst preparation procedure was applied. First, 0.1120 g of the activated carbon powder was added to 100 mL solution for electroless plating of Co, containing 5 × 10−2 M CoSO4·7H2O, 0.2 M NaH2PO2·H2O and 5 × 10−2 M Na3C6H5O7·2H2O. The pH value was adjusted to 10 with aqueous ammonia. The electroless plating was performed for 60 min under magnetic stirring at 85 °C. The suspension was filtered and the obtained Co-P/C material was rinsed with H2O and left to dry in air. Second, 0.1270 g of the as-prepared Co-P/C powder precursor was slowly added to 25 mL of 0.1 M HCl solution containing 5 × 10−3 M K2PtCl6 salt (Sigma-Aldrich, ACS reagent, Merck Bulgaria EAD). Platinization occurs under continuous magnetic stirring for 60 min and nitrogen purging, due to the difference in the standard reduction potentials of the two metals:
Co(OH)2 + 2 e− → Co + 2 OH−  (E0 = −0.73 V)
[PtCl6]2− + 4 e− → Pt + 6 Cl−      (E0 = +0.744 V)
The obtained precipitate was rinsed many times with H2O and left to dry.

3.2. Material Characterization

The composition of the prepared Co-P/C precursor and Pt-Co/C catalyst was analyzed by EDS using a SEM JSM 6390 (Munich, Germany) equipped with an INCA Oxford Energy 350 system. A JEOL JEM 2100 High-Resolution Transmission Electron Microscope (HRTEM) (Tokyo, Japan) and a CCD camera: Gatan Orius 1000 (Pleasanton, CA, USA), model EDS: Oxford Instruments X-Max 80T (Tokyo, Japan) were used to study the morphology and perform spot analyses of the catalysts. X-ray powder diffraction was carried out by an Empyrean diffractometer, equipped with Cu anode (30 kV, 40 mA) and Cu Kα filtered radiation (λ = 1.5406 Å) (Almelo, The Netherlands). XPS studies were performed in a VG ESCALAB MK II electron spectrometer (Waltham, MA, USA) using achromatic Al Kα (1486.6 eV) radiation under base pressure of 1 × 10−8 Pa. The spectrometer was calibrated against the Au4f7/2 line (84.0 eV) and the samples’ charging was estimated from C 1s (285 eV) spectra from natural hydrocarbon contaminations on the surface. The spectrometer resolution was calculated from the Ag3d5/2 line (FWHM = 1 eV) with the analyzer transmission energy of 20 eV. The X-ray photoelectron spectra of C 1s, O 1s, Pt 4f and Co 2p were recorded and corrected by subtracting a Shirley-type background and quantified using the peak area and Scofield’s photoionization cross-sections. The accuracy of the measured BE was 0.2 eV.
CV and LSV experiments were performed to study the electrochemical behavior and electrocatalytic activity of the Pt-Co/C composite towards ORR and to compare them with those of the commercial 20 wt.% Pt/C catalyst (ETEK). An Autolab PGSTAT302N (EcoChemie, Utrecht, The Netherlands) system equipped with the FRA32 module and Nova 1.11.2 software was used. The electrochemical experiments were conducted in nitrogen-deaerated 0.1 M HClO4 (Merck, pro analysis, Darmstadt, Germany) solutions using a standard three-electrode electrochemical cell with a saturated calomel reference electrode (SCE—all potentials are then converted with respect to the reversible hydrogen electrode, RHE), with a Luggin capillary and a Pt foil as a counter electrode.
The suspension for the working electrode was prepared as follows: 1 mg of the catalyst was ultrasonically homogenized in a mixture of 0.5 mL H2O and 0.5 mL of isopropanol containing 8.86 μL of Nafion® (5% w/w solution, Sigma-Aldrich, Merck, Darmstadt, Germany). A glassy carbon (GC) rotating disc electrode (RDE, Eco Chemie, Utrecht, The Netherlands) with a geometric area of 0.07 cm2 was used as a substrate. The suspension was drop-casted on the RDE, the Catalyst + Nafion® loading being controlled by simultaneously weighing the same number of drops cast on an aluminum foil. The loading of Pt on the RDE was 0.05 mg cm−2. Electrode with a commercial Pt/C ETEK catalyst was prepared in a similar way for comparison.
The surface electrochemistry of Pt-Co/C and Pt/C electrodes was studied by CV experiments, performed between 0.00 V and +1.60 V vs. RHE (potential values at the onset of hydrogen and oxygen evolution), at a 200 mV s−1 potential sweep rate, until stabilization. The catalytic activity towards ORR was investigated using LSV in the potential range from +0.8 V to −0.3 V at 5 mV s−1 in oxygen-saturated 0.1 M HClO4 solutions for various electrode rotation speeds (100–2500 rpm). The current interrupt method was used in order to estimate and correct for uncompensated resistance.

4. Conclusions—Further Work

(i)
A low Co-content Pt-Co/C nanocatalyst (up to ca 1 wt.% Co and of a Pt ÷ Co atom ratio of 7:1) was successfully prepared by a generic, low-energy, and chemistry-intensive preparation route that involves electroless deposition Co-P onto C, followed by spontaneous partial galvanic replacement of Co and Co(OH)2 with Pt. Further work should aim at minimizing the precursor Co content as well as reclaiming/reusing the etched Co(II) species.)
(ii)
The used alternative method results in the formation of a Co-Pt core-shell structure. Further work should aim at testing the long-term performance of the catalyst to investigate whether this structure prevents gradual Co leaching during operation.
(iii)
Despite the presence of large catalyst aggregates and a relatively low surface area, the higher activity in Pt-Co/C may be attributed to its optimized composition and structure, facilitating efficient ORR as a result of the well-known modification of the electronic properties of Pt by less noble transition metals.

Author Contributions

A.B.: data curation, formal analysis. I.A.: formal analysis. S.S.: conceptualization, data curation, writing—review and editing. J.G.: conceptualization, data curation, writing—original draft preparation. All authors have read and agreed to the published version of the manuscript.

Funding

This research received no external funding.

Data Availability Statement

All data generated or analyzed during this study are included in this published article.

Acknowledgments

The support from the Bulgarian Academy of Sciences (Bilateral research project between BAS and the Aristotle University of Thessaloniki (AUTH), Greece) is gratefully acknowledged.

Conflicts of Interest

The authors declare no conflicts of interest.

References

  1. Srinivasan, S. Fuel Cells: From Fundamentals to Applications; Springer Science: New York, NY, USA, 2006. [Google Scholar]
  2. Rimon, S.T.A.; Mourshed, M.; Kibria, M.G. Proton exchange membrane fuel cells: Advances in materials development, performance optimization, and future outlook. Energy Convers. Manag. X 2025, 27, 101102–101153. [Google Scholar] [CrossRef]
  3. Kumar, V.B.; Collin, A.; Sankar, M.G.; Subramanian, K. Fuel cell technologies in the automotive sector: A focus on proton exchange membrane and Alkaline fuel cells. Green Technol. Sustain. 2025, 3, 100218–100236. [Google Scholar] [CrossRef]
  4. Zhang, L.; Zhang, J.; Wilkinson, D.P.; Wang, H. Progress in preparation of non-noble electrocatalysts for PEM fuel cell reactions. J. Power Sources 2006, 156, 171–182. [Google Scholar] [CrossRef]
  5. Gewirth, A.A.; Thorum, M.S. Electroreduction of dioxygen for fuel-cell applications: Materials and challenges. Inorg. Chem. 2010, 49, 3557–3566. [Google Scholar] [CrossRef]
  6. Norskov, J.K.; Rossmeisl, J.; Logadottir, A.; Lindqvist, L.; Kitchin, J.R.; Bligaard, T.; Jonsson, H. Origin of the Overpotential for Oxygen Reduction at a Fuel-Cell Cathode. J. Phys. Chem. B 2004, 108, 17886–17892. [Google Scholar] [CrossRef]
  7. Chen, Y.; Huang, Z.; Yu, J.; Wang, H.; Qin, Y.; Xing, L.; Du, L. Research Progress of Pt-Based Catalysts toward Cathodic Oxygen Reduction Reactions for Proton Exchange Membrane Fuel Cells. Catalysts 2024, 14, 569. [Google Scholar] [CrossRef]
  8. Zhan, F.; Huang, L.; Luo, Y.; Chen, M.; Tan, R.; Liu, X.; Liu, G.; Feng, Z. Recent advances on support materials for enhanced Pt-based catalysts: Applications in oxygen reduction reactions for electrochemical energy storage. J. Mater. Sci. 2025, 60, 2199–2223. [Google Scholar] [CrossRef]
  9. Antolini, E.; Zignani, S.; Santos, S.; Gonzalez, E. Palladium-based electrodes: A way to reduce platinum content in polymer electrolyte membrane fuel cells. Electrochim. Acta 2011, 56, 2299–2305. [Google Scholar] [CrossRef]
  10. Huang, L.; Xu, H.-C.; Jing, B.; Li, Q.-X.; Yi, W.; Sun, S.-G. Progress of Pt-Based Catalysts in Proton-Exchange Membrane Fuel Cells. J. Electrochem. 2022, 28, 2108061–2108078. [Google Scholar]
  11. Lee, S.-Y.; Kim, M.-K.; Son, U.-H.; Han, S.; Lee, S.; Joh, H.-I. Recent progress of low-loaded platinum on well-functionalized carbon electrocatalysts for oxygen reduction reaction. Carbon Lett. 2025, 35, 107–127. [Google Scholar] [CrossRef]
  12. Mohd Nor, M.A.A.; Abdul Rani, M.A.A.; Loh, K.S.; Choo, T.F.; Lim, K.L.; Osman, S.H.; Loy, A.C.M.; Wong, W.Y. Maximizing oxygen reduction reaction performance with minimal Pt: A review of high mass activity Pt-M catalysts. J. Power Sources 2025, 654, 237869–237892. [Google Scholar] [CrossRef]
  13. Cao, F.; Ding, R.; Rui, Z.; Wang, X.; Meng, Z.; Zhang, B.; Dong, W.; Li, J.; Liu, J.; Jiang, X. Advances in Low Pt Loading Membrane Electrode Assembly for Proton Exchange Membrane Fuel Cells. Molecules 2023, 28, 773. [Google Scholar] [CrossRef]
  14. Geboes, B.; Mintsouli, I.; Wouters, B.; Georgieva, J.; Kakaroglou, A.; Sotiropoulos, S.; Valova, E.; Armyanov, S.; Hubin, A.; Breugelmans, T. Surface and electrochemical characterisation of a Pt-Cu/C nano-structured electrocatalyst, prepared by galvanic displacement. Appl. Catal. B Environ. 2014, 150–151, 249–256. [Google Scholar] [CrossRef]
  15. Shao, M.; Chang, Q.; Dodelet, J.-P.; Chenitz, R. Recent Advances in Electrocatalysts for Oxygen Reduction Reaction. Chem. Rev. 2016, 116, 3594–3657. [Google Scholar] [CrossRef]
  16. Zhao, Y.; Liu, J.; Zhao, Y.; Wang, F. Composition-controlled synthesis of carbon-supported Pt–Co alloy nanoparticles and the origin of their ORR activity enhancement. Phys. Chem. Chem. Phys. 2014, 16, 19298–19306. [Google Scholar] [CrossRef] [PubMed]
  17. Salgado, J.R.C.; Antolini, E.; Gonzalez, E.R. Structure and Activity of Carbon-Supported Pt-Co Electrocatalysts for Oxygen Reduction. Phys. Chem. B 2004, 108, 17767–17774. [Google Scholar] [CrossRef]
  18. Weber, P.; Weber, D.J.; Dosche, C.; Oezaslan, M. Durable Pt-Based Core–Shell Catalysts with Metallic and Oxidized Co Species for Boosting the Oxygen Reduction Reaction. ACS Catal. 2022, 12, 6394–6408. [Google Scholar] [CrossRef]
  19. Shen, J.-F.; Hu, S.-N.; Tian, N.; Li, M.-Y.; Yang, S.-L.; Tian, S.-Y.; Chen, M.-S.; Zhou, Z.-Y.; Sun, S.-G. P-Doping Strategy Increasing the Durability of PtCo Nanoparticles for the Oxygen Reduction Reaction. ACS Sustain. Chem. Eng. 2023, 11, 11660–11667. [Google Scholar] [CrossRef]
  20. Stamenkovic, V.R.; Mun, B.S.; Arenz, M.; Mayrhofer, K.J.J.; Lucas, C.A.; Wang, G.; Ross, P.N.; Markovic, N.M. Trends in Electrocatalysis on Extended and Nanoscale Pt-Bimetallic Alloy Surfaces. Nat. Mater. 2007, 6, 241–247. [Google Scholar] [CrossRef]
  21. Koh, S.; Leisch, J.; Toney, M.F.; Strasser, P. Structure-Activity-Stability Relationships of Pt-Co Alloy Electrocatalysts in Gas-Diffusion Electrode Layers. J. Phys. Chem. C 2007, 111, 3744–3752. [Google Scholar] [CrossRef]
  22. Oezaslan, M.; Strasser, P. Activity of dealloyed PtCo3 and PtCu3 nanoparticle electrocatalyst for oxygen reduction reaction in polymer electrolyte membrane fuel cell. J. Power Sources 2011, 196, 5240–5249. [Google Scholar] [CrossRef]
  23. Wang, X.X.; Hwang, S.; Pan, Y.T.; Chen, K.; He, Y.; Karakalos, S.; Zhang, H.; Spendelow, J.S.; Su, D.; Wu, G. Ordered Pt3Co intermetallic nanoparticles derived from metal-organic frameworks for oxygen reduction. Nano Lett. 2018, 18, 4163–4171. [Google Scholar] [CrossRef] [PubMed]
  24. Yang, B.; Yu, X.; Hou, J.; Xiang, Z. Secondary reduction strategy synthesis of Pt–Co nanoparticle catalysts towards boosting the activity of proton exchange membrane fuel cells. Particuology 2023, 79, 18–26. [Google Scholar] [CrossRef]
  25. Antolini, E. Platinum-based ternary catalysts for low temperature fuel cells: Part I. Preparation methods and structural characteristics. Appl. Catal. B Environ. 2007, 74, 324–336. [Google Scholar] [CrossRef]
  26. Antolini, E. Carbon supports for low-temperature fuel cell catalysts. Appl. Catal. B Environ. 2009, 88, 1–24. [Google Scholar] [CrossRef]
  27. Brankovic, S.R.; Wang, J.X.; Adžić, R.R. Metal monolayer deposition by replacement of metal adlayers on electrode surfaces. Surf. Sci. Lett. 2001, 474, L173–L179. [Google Scholar] [CrossRef]
  28. Van Brussel, M.; Kokkinidis, G.; Vandendael, I.; Buess-Herman, C. High performance gold-supported platinum electrocatalyst for oxygen reduction. Electrochem. Commun. 2002, 4, 808–813. [Google Scholar] [CrossRef]
  29. Papadimitriou, S.; Tegou, A.; Pavlidou, E.; Kokkinidis, G.; Sotiropoulos, S. Methanol oxidation at platinized lead coatings prepared by a two-step electrodeposition–electroless deposition process on glassy carbon and platinum substrates. Electrochim. Acta 2007, 52, 6254–6260. [Google Scholar] [CrossRef]
  30. Tegou, A.; Papadimitriou, S.; Armyanov, S.; Valova, E.; Kokkinidis, G.; Sotiropoulos, S. Oxygen reduction at platinum- and gold-coated iron, cobalt, nickel and lead deposits on glassy carbon substrates. J. Electroanal. Chem. 2008, 623, 187–196. [Google Scholar] [CrossRef]
  31. Tegou, A.; Papadimitriou, S.; Kokkinidis, G.; Sotiropoulos, S. A rotating disc electrode study of oxygen reduction at platinised nickel and cobalt coatings. J. Solid State Electrochem. 2010, 14, 175–184. [Google Scholar] [CrossRef]
  32. Papadimitriou, S.; Armyanov, S.; Valova, E.; Hubin, A.; Steenhaut, O.; Pavlidou, E.; Kokkinidis, G.; Sotiropoulos, S. Methanol Oxidation at Pt−Cu, Pt−Ni, and Pt−Co Electrode Coatings Prepared by a Galvanic Replacement Process. J. Phys. Chem. C 2010, 114, 5217–5223. [Google Scholar] [CrossRef]
  33. Mintsouli, I.; Georgieva, J.; Valova, E.; Armyanov, S.; Kakaroglou, A.; Hubin, A.; Steenhaut, O.; Dille, J.; Papaderakis, A.; Kokkinidis, G.; et al. Pt–Ni carbon-supported catalysts for methanol oxidation prepared by Ni electroless deposition and its galvanic replacement by Pt. J. Solid State Electrochem. 2013, 17, 435–443. [Google Scholar] [CrossRef]
  34. Mintsouli, I.; Georgieva, J.; Armyanov, S.; Valova, E.; Avdeev, G.; Hubin, A.; Steenhaut, O.; Dille, J.; Tsiplakides, D.; Balomenou, S.; et al. Pt-Cu electrocatalysts for methanol oxidation prepared by partial galvanic replacement of Cu/carbon powder precursors. Appl. Catal. B Environ. 2013, 136–137, 160–167. [Google Scholar] [CrossRef]
  35. Georgieva, J.; Valova, E.; Mintsouli, I.; Sotiropoulos, S.; Armyanov, S.; Kakaroglou, A.; Hubin, A.; Steenhaut, O.; Dille, J. Carbon-supported Pt(Cu) electrocatalysts for methanol oxidation prepared by Cu electroless deposition and its galvanic replacement by Pt. J. Appl. Electrochem. 2014, 44, 215–224. [Google Scholar] [CrossRef]
  36. Mintsouli, I.; Georgieva, J.; Papaderakis, A.; Armyanov, S.; Valova, E.; Khomenko, V.; Balomenou, S.; Tsiplakides, D.; Sotiropoulos, S. Methanol oxidation at platinized copper particles prepared by galvanic replacement. J. Electrochem. Sci. Eng. 2016, 6, 17–28. [Google Scholar] [CrossRef]
  37. Li, F.; Zhu, Y.; Ueno, H.; Deng, T. An Electrochemically Prepared Mixed Phase of Cobalt Hydroxide/Oxyhydroxide as a Cathode for Aqueous Zinc Ion Batteries. Inorganics 2023, 11, 400. [Google Scholar] [CrossRef]
  38. Chetty, R.; Kundu, S.; Xia, W.; Bron, M.; Schuhmann, W.; Chirila, V.; Brandl, W.; Reinecke, T.; Muhler, M. PtRu nanoparticles supported on nitrogen-doped multiwalled carbon nanotubes as catalyst for methanol electrooxidation. Electrochim. Acta 2009, 54, 4208–4215. [Google Scholar] [CrossRef]
  39. Gasteiger, H.A.; Kocha, S.K.; Sompalli, B.; Wagner, F.T. Activity benchmarks and requirements for Pt, Pt-alloy, and non-Pt oxygen reduction catalysts for PEMFCs. Appl. Catal. B Environ. 2005, 56, 9–35. [Google Scholar] [CrossRef]
  40. Papaderakis, A.; Matouli, I.; Spyridou, O.N.; Grammenos, A.O.; Banti, A.; Touni, A.; Pliatsikas, N.; Panagiotis Patsalas, P.; Sotiropoulos, S. Ternary IrO2-Pt-Ni deposits prepared by galvanic replacement as bifunctional oxygen catalysts. J. Electroanal. Chem. 2020, 877, 114499–114510. [Google Scholar] [CrossRef]
  41. Chen, Y.; Jin, Z.; Sun, J.; Chen, S.; Zhang, J.; Zhang, S. Precise Pt-skin manipulation of strain and ligand effects for oxygen reduction. eScience 2025, 5, 100396–100408. [Google Scholar] [CrossRef]
  42. Jeon, M.K.; Zhang, Y.; McGinn, P.J. A comparative study of PtCo, PtCr, and PtCoCr catalysts for oxygen electro-reduction reaction. Electrochim. Acta 2010, 55, 5318–5325. [Google Scholar] [CrossRef]
  43. He, Q.; Mukerjee, S. Electrocatalysis of oxygen reduction on carbon-supported PtCo catalysts prepared by water-in-oil micro-emulsion. Electrochim. Acta 2010, 55, 1709–1719. [Google Scholar] [CrossRef]
  44. Jeon, M.K.; McGinn, P.J. Co-alloying effect of Co and Cr with Pt for oxygen electro-reduction reaction. Electrochim. Acta 2012, 64, 147–153. [Google Scholar] [CrossRef]
  45. Shinozaki, K.; Zack, J.W.; Pylypenko, S.; Richards, R.M.; Pivovar, B.S.; Kocha, S.S. Benchmarking the oxygen reduction reaction activity of Pt-based catalysts using standardized rotating disk electrode methods. Int. J. Hydrogen Energy 2015, 40, 16820–16830. [Google Scholar] [CrossRef]
  46. Cai, Y.; Gao, P.; Wang, F.; Zhu, H. Carbon supported chemically ordered nanoparicles with stable Pt shell and their superior catalysis toward the oxygen reduction reaction. Electrochim. Acta 2017, 245, 924–933. [Google Scholar] [CrossRef]
  47. Gunnarson, A.; De Bellis, J.; Imhof, T.; Pfänder, N.; Ledendecker, M.; Schüth, F. Facile Solid-State Synthesis of Supported PtNi and PtCo Bimetallic Nanoparticles for the Oxygen Reduction Reaction. Chem. Mater. 2023, 35, 2006–2015. [Google Scholar] [CrossRef]
  48. Xu, W.-C.; Zhang, Z.-M.; Yang, C.-H.; Zhao, K.-M.; Wang, Y.; Tian, N.; Zhou, Z.-Y.; Sun, S.-G. Promotion mechanism of PtCo intermetallic ordered alloys in oxygen reduction reaction and its application in fuel cells. Electrochem. Commun. 2023, 152, 107516–107522. [Google Scholar] [CrossRef]
  49. Yin, S.; Song, Y.; Liu, H.; Cui, J.; Liu, Z.; Li, Y.; Xue, T.; Tang, W.; Zhang, D.; Li, H.; et al. Well-Defined PtCo@Pt Core-Shell Nanodendrite Electrocatalyst for Highly Durable Oxygen Reduction Reaction. Small 2025, 21, 2410080. [Google Scholar] [CrossRef] [PubMed]
  50. Ando, Y.; Sasaki, K.; Adzic, R.R. Electrocatalysts for methanol oxidation with ultra low content of Pt and Ru. Electrochem. Commun. 2009, 11, 1135–1138. [Google Scholar] [CrossRef]
Catalysts 15 00895 g001
Figure 1. TEM micrographs of Co-P/C (a), Pt-Co/C (b) and the corresponding histogram of area-equivalent circle diameter of Pt-Co/C catalyst (c).
Figure 1. TEM micrographs of Co-P/C (a), Pt-Co/C (b) and the corresponding histogram of area-equivalent circle diameter of Pt-Co/C catalyst (c).
Catalysts 15 00895 g001
Catalysts 15 00895 g002
Figure 2. TEM-EDS spot chemical analyses and mapping of Pt-Co/C catalyst aggregates.
Figure 2. TEM-EDS spot chemical analyses and mapping of Pt-Co/C catalyst aggregates.
Catalysts 15 00895 g002
Catalysts 15 00895 g003
Figure 3. XRD patterns of Co-P/C precursor (a) and Pt-Co/C nanocatalyst (b); Reference codes: Co(OH)2 98-008-8940, CoO 98-002-9082, Co 98-007-6942, C 98-061-7290, Pt 98-006-4924, CoOOH 98-002-0566.
Figure 3. XRD patterns of Co-P/C precursor (a) and Pt-Co/C nanocatalyst (b); Reference codes: Co(OH)2 98-008-8940, CoO 98-002-9082, Co 98-007-6942, C 98-061-7290, Pt 98-006-4924, CoOOH 98-002-0566.
Catalysts 15 00895 g003
Catalysts 15 00895 g004
Figure 4. X-ray photoelectron spectra of the Pt-Co/C catalyst in the C 1s (a); O 1s (b); Pt 4f (c) and Co 2p (d) binding energy ranges.
Figure 4. X-ray photoelectron spectra of the Pt-Co/C catalyst in the C 1s (a); O 1s (b); Pt 4f (c) and Co 2p (d) binding energy ranges.
Catalysts 15 00895 g004
Catalysts 15 00895 g005
Figure 5. Voltammograms of Pt-Co/C and Pt/C catalysts at 200 mV s−1 in deaerated 0.1 M HClO4.
Figure 5. Voltammograms of Pt-Co/C and Pt/C catalysts at 200 mV s−1 in deaerated 0.1 M HClO4.
Catalysts 15 00895 g005
Catalysts 15 00895 g006
Figure 6. LSV curves of Pt-Co/C catalyst at 20 mV s−1 in an oxygen-saturated 0.1 M HClO4 solution at different electrode rotation speeds (a) and the corresponding Koutecky–Levich plot (b).
Figure 6. LSV curves of Pt-Co/C catalyst at 20 mV s−1 in an oxygen-saturated 0.1 M HClO4 solution at different electrode rotation speeds (a) and the corresponding Koutecky–Levich plot (b).
Catalysts 15 00895 g006
Catalysts 15 00895 g007
Figure 7. ORR polarization curves of Pt-Co/C and Pt/C catalysts at 1600 rpm, normalized by geometric area (a) and by platinum mass (b).
Figure 7. ORR polarization curves of Pt-Co/C and Pt/C catalysts at 1600 rpm, normalized by geometric area (a) and by platinum mass (b).
Catalysts 15 00895 g007
Catalysts 15 00895 g008
Figure 8. Tafel plots for Pt-Co/C and Pt/C catalysts (Pt esa-specific current density in mA cmPt−2).
Figure 8. Tafel plots for Pt-Co/C and Pt/C catalysts (Pt esa-specific current density in mA cmPt−2).
Catalysts 15 00895 g008
Table 1. Composition of Co-P/C and Pt-Co/C catalysts.
Table 1. Composition of Co-P/C and Pt-Co/C catalysts.
SampleCo wt.%P wt.%Pt wt.%
Co-P/C240.4
Pt-Co/C0.7017
Table 2. Catalytic performance of Pt and Pt-Co catalysts on Vulcan support at different overpotentials (η = −330 mV and η = −380 mV).
Table 2. Catalytic performance of Pt and Pt-Co catalysts on Vulcan support at different overpotentials (η = −330 mV and η = −380 mV).
CatalystInitial Co
wt.%		Pt
wt.%		Co
wt.%		Pt mass
Specific Area,
m2 g−1		Jm/mA mg−1Jesa/mA cm−2
η = −330 mV
Pt/C0200319.930.032
Pt-Co/C28170.71936.60.182
η = −380 mV
Pt/C02003150.60.165
Pt-Co/C28170.7191330.661
Table 3. Comparison of the catalytic performance of C-supported Pt-Co catalysts towards ORR, presented as the enhancement factor of both the area-specific current density (Jesa/mA cmPt−2) and the Pt mass-specific current density (Jm/mA mgPt−1) at E = +0.90 V vs. RHE, with respect to their Pt/C analogues.
Table 3. Comparison of the catalytic performance of C-supported Pt-Co catalysts towards ORR, presented as the enhancement factor of both the area-specific current density (Jesa/mA cmPt−2) and the Pt mass-specific current density (Jm/mA mgPt−1) at E = +0.90 V vs. RHE, with respect to their Pt/C analogues.
ReferenceJesa
Enhancement Factor 		Jm
Enhancement Factor
[18]124
[21]3-
[22]53
[42]
(annealed)		7
(3)		0.5
(1)
[43]51
[44]
(annealed)		2
(3)		1
(0.5)
[45]21
[46]2.53
[47]47
[48]96
[49]143
[this work]74
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content.

Share and Cite

MDPI and ACS Style

Banti, A.; Avramova, I.; Sotiropoulos, S.; Georgieva, J. Enhanced Oxygen Reduction Reaction Activity of Carbon-Supported Pt-Co Catalysts Prepared by Electroless Deposition and Galvanic Replacement. Catalysts 2025, 15, 895. https://doi.org/10.3390/catal15090895

AMA Style

Banti A, Avramova I, Sotiropoulos S, Georgieva J. Enhanced Oxygen Reduction Reaction Activity of Carbon-Supported Pt-Co Catalysts Prepared by Electroless Deposition and Galvanic Replacement. Catalysts. 2025; 15(9):895. https://doi.org/10.3390/catal15090895

Chicago/Turabian Style

Banti, Angeliki, Ivalina Avramova, Sotiris Sotiropoulos, and Jenia Georgieva. 2025. "Enhanced Oxygen Reduction Reaction Activity of Carbon-Supported Pt-Co Catalysts Prepared by Electroless Deposition and Galvanic Replacement" Catalysts 15, no. 9: 895. https://doi.org/10.3390/catal15090895

APA Style

Banti, A., Avramova, I., Sotiropoulos, S., & Georgieva, J. (2025). Enhanced Oxygen Reduction Reaction Activity of Carbon-Supported Pt-Co Catalysts Prepared by Electroless Deposition and Galvanic Replacement. Catalysts, 15(9), 895. https://doi.org/10.3390/catal15090895

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

Article Metrics

Back to TopTop