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Article

Pt Nanoparticles Supported on Mesoporous Hollow TiO2@C Sphere Composite as Efficient Methanol Oxidation Reaction Electrocatalysts

by
Yuan Chen
1,
Huiyuan Liu
1,
Qiang Ma
1,
Zhuo Li
1,
Mengyue Lu
1,
Huaneng Su
1,
Weiqi Zhang
1,2,3,* and
Qian Xu
1,3,*
1
Institute for Energy Research, Jiangsu University, 301 Xuefu Road, Zhenjiang 212013, China
2
Key Laboratory of Power Machinery and Engineering of Ministry of Education, Shanghai Jiao Tong University, Shanghai 200240, China
3
Key Laboratory of Advanced Electrode Materials for Novel Solar Cells for Petroleum and Chemical Industry of China, School of Chemistry and Life Sciences, Suzhou University of Science and Technology, Suzhou 215009, China
*
Authors to whom correspondence should be addressed.
Catalysts 2025, 15(9), 834; https://doi.org/10.3390/catal15090834
Submission received: 19 July 2025 / Revised: 20 August 2025 / Accepted: 27 August 2025 / Published: 1 September 2025
(This article belongs to the Special Issue Tailored Nanosystems and Nanocatalysts for Photo-/Electrocatalytic Applications, 2nd Edition)
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Abstract

The large-scale implementation of direct methanol fuel cells (DMFCs) is significantly impeded by sluggish methanol oxidation reaction (MOR) kinetics, degradation of Pt electrocatalysts, and significant carbon support corrosion in commercial Pt/C. Herein, we design a mesoporous hollow TiO2@carbon core–shell composite (MH-TiO2@C) as a support for Pt nanoparticles to serve as an efficient MOR electrocatalyst. Pt/MH-TiO2@C demonstrates exceptional MOR activity in alkaline electrolyte, exhibiting a mass activity 2.56-fold higher than commercial Pt/C. Furthermore, Pt/MH-TiO2@C displays remarkable durability compared to Pt/C. Following chronoamperometry tests, the mass activity of Pt/MH-TiO2@C decreased by 30.92%, substantially lower than the 52.31% loss observed for commercial Pt/C. The superior MOR activity and durability originate from the inherent structural stability of the MH-TiO2@C composite, strong metal-support interaction between Pt and TiO2, and enhanced resistance to intermediate poisoning. This work presents a feasible strategy for developing efficient and durable Pt-based electrocatalysts, accelerating the commercialization of DMFCs.

1. Introduction

Nowadays, carbon neutrality and global-scale sustainable energy goals accelerate the demand for renewable energy equipment. Direct methanol fuel cells (DMFCs) have attracted considerable interest as promising green power sources for portable applications due to their high energy density, ambient operating conditions, and simpler storage and transportation of liquid methanol fuel compared to gaseous hydrogen [1,2,3]. Despite these advantages, the widespread implementation of DMFC technology is hindered by sluggish methanol oxidation reaction (MOR) kinetics at the anode and inadequate electrocatalyst durability during long-term operation [4,5].
Pt nanoparticles (NPs) supported on carbon black (Pt/C) are widely used as the anode electrocatalysts in DMFC. However, Pt/C suffers from the critical limitations including carbon support corrosion, Pt degradation, and carbonaceous intermediates poisoning [6,7,8]. The electrochemical oxidation of carbon support is prone to occur, particularly at high potentials exceeding 0.9 V vs. reversible hydrogen electrode (RHE), through the following mechanisms [9,10]:
C + 2H2O → CO2 + 4H+ + 4e−, E0 = 0.207 V vs. RHE,
C + H2O → CO + 2H+ + 2e−, E0 = 0.518 V vs. RHE.
Moreover, it has been reported that severe corrosion occurs at 0.6–0.9 V vs. RHE for the carbon support in contact with Pt NPs [11,12]. Carbon corrosion leads to the detachment and aggregation of Pt NPs, resulting in a loss of electrochemical surface area (ECSA). The degradation mechanisms of Pt NPs involve dissolution, growth, and agglomeration [13,14]. This irreversible Pt degradation reduces the ECSA, leading to the performance decay of DMFC. In addition, during Pt-catalyzed methanol oxidation, the reaction proceeds primarily through an indirect pathway wherein adsorbed carbon monoxide (COads) is oxidized by adsorbed hydroxyl species (OHads) on the Pt surface to form CO2 [15]. However, the strong adsorption of intermediates (e.g., COads) on Pt active sites inhibits the MOR pathway, reducing Pt utilization efficiency [16,17]. Although various Pt-free electrocatalysts with COads resistance have been developed, their MOR activity has yet to meet the requirement of practical DMFC applications [18]. These synergistic degradation behaviors result in significant deterioration in DMFC performance and increased operational costs. Consequently, advanced Pt-based electrocatalysts must be developed with enhanced MOR activity, durability, and improved poisoning resistance.
The development of novel supports and support engineering strategies is effective ways to obtain the high-performance Pt-based electrocatalysts [19,20]. TiO2 emerges as a promising alternative support due to: (i) exceptional stability in harsh environments; (ii) low cost and abundance; and (iii) tunable electronic properties via strong metal-support interaction (SMSI). The SMSI between Pt and TiO2 downshifts the Pt d-band center, weakening COads adsorption energy while optimizing OHads binding energy on Pt active sites [21,22]. This electronic modulation also enhances the anchoring strength of Pt NPs, which stabilizes Pt NPs against dissolution and aggregation [23]. In addition, as demonstrated by Li et al., TiO2 possesses the co-catalytic mechanism, which further promotes COads oxidation through surface OHads enrichment during methanol oxidation [24]. Wang et al. prepared Ru@Pt/C-TiO2 through a two-step ethanol reduction method [25]. Compared with Ru@Pt/C, Ru@Pt/C-TiO2 exhibited higher MOR activity, durability, and COads tolerance. The enhanced MOR performance is ascribed to the SMSI (between Pt and TiO2) and bifunctional mechanism derived from TiO2, which promotes water dissociation and anchors -OH group to facilitate the oxidation of COads on Pt. Furthermore, SMSI effects enable robust anchoring of Pt NPs on TiO2 surfaces, suppressing Pt NP growth, migration, and aggregation [26]. However, the inherently low electrical conductivity of TiO2 imposes severe charge transfer limitations. Our previous research has shown that using TiO2 alone as Pt supports is not helpful in constructing high-performance electrocatalysts [27].
A hybrid architecture integrating TiO2 with highly conductive carbon materials has been demonstrated as an effective strategy for improving electronic conductivity [28]. Qian et al. developed a mesoporous hollow carbon sphere (MHCS) supported Pt NPs (Pt@HC-meso) using a double-template method [29]. Pt@HC-meso exhibited excellent activity and durability for MOR due to the novel structure of MHCS, which can provide fast and efficient charge transfer, accessible diffusion pathways for reactants, and protection of Pt NPs from migration and agglomeration. Thus, we deduce that when MHCS integrates with TiO2 as the Pt support, the resulting electrocatalyst would achieve the properties of good electrical conductivity, high MOR activity and durability, and notable resistance to COads.
In this study, a silica nanosphere (NS) template-assisted method was employed to fabricate mesoporous hollow TiO2@C core–shell composites. The resulting Pt/MH-TiO2@C electrocatalyst features the well-defined mesoporous hollow architecture and uniformly dispersed Pt NPs with an average size of 2.9 nm. As we deduced, Pt/MH-TiO2@C exhibited superior MOR activity and durability in alkaline electrolyte compared to commercial Pt/C. This approach established a promising strategy for developing advanced Pt-based electrocatalysts with exceptional MOR performance.

2. Results and Discussion

The morphology of the synthesized SiO2 NSs was characterized by scanning electron microscopy (SEM) [30]. As shown in Figure S1a,b, the SiO2 NSs exhibited a uniform size distribution with an average diameter of ~380 nm. Following the preparation of the TiO2 layer on the SiO2 NS, an increase in surface roughness was observed (Figure 1a and Figure S1c). After the carbon layer synthesis on the SiO2@TiO2 NS, the MH-TiO2@C composite was obtained through etching in a concentrated NaOH aqueous solution to remove the SiO2 template. EDS analysis confirms the existence of Ti, O, and C, further proving the formation of mesoporous hollow TiO2@Carbon spheres (Figure S1e). The formation of hollow structures in MH-TiO2@C is clearly demonstrated in Figure 1b and Figure S1d.
N2 adsorption–desorption tests of SiO2@TiO2@C and MH-TiO2@C were conducted to analyze their surface areas and pore properties before and after etching. Both N2 adsorption–desorption isotherms exhibited type-IV with a type-H3 hysteresis loop (Figure 1c), indicating the presence of micro- and mesopores [31,32]. Notably, etching induced a substantial increase in total pore volume and a significant rise in the mesopore volume ratio from 42.90% to 93.14% (Table S1). Additionally, the average pore size increased from 2.62 nm to 5.05 nm (Figure 1d), while the Brunauer–Emmett–Teller (BET) surface area rosed from 177 m2 g−1 to 263 m2 g−1 (Table S1). These features of MH-TiO2@C, including expanded microporosity and surface area, are anticipated to improve mass transport and expose additional active sites, thereby accelerating MOR kinetics [19,33,34].
As illustrated in Figure 2a–c, the SEM images of Pt/MH-TiO2@C reveal a morphology consistent with MH-TiO2@C, featuring a hollow structure and a porous surface. The corresponding energy-dispersive X-ray spectroscopy (EDS) elemental mapping images in Figure 2d confirm the uniform distribution of Pt, C, Ti, and O over Pt/MH-TiO2@C. Notably, Figure 2c and the Pt mapping image in Figure 2d demonstrate that Pt NPs reside not only on the surface but also within the MH-TiO2@C spheres.
Transmission electron microscopy (TEM) analysis of Pt/MH-TiO2@C (Figure 3a) confirms the hollow structured NS with a shell thickness of ~60 nm. Figure 3b,c shows uniformly dispersed Pt NPs (average size: 2.9 nm) without significant aggregation. Fast Fourier transform (FFT) and inverse fast Fourier transform (IFFT) analyses of selected regions (yellow boxes in Figure 3d,f) reveal lattice spacing of 0.355 nm, corresponding to the anatase TiO2 (101) plane (Figure 3e) and lattice spacing of 0.227 nm, corresponding to the face-centered cubic (fcc) Pt (111) plane (Figure 3g) [35,36]. High-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) image and the corresponding elemental mappings of Pt/MH-TiO2@C in Figure 3h, along with the line-scan analysis in Figure S2, disclose that most Pt NPs are uniformly distributed on the MH-TiO2@C surface, with a minority localized inside it.
The crystalline structures of Pt/MH-TiO2@C and MH-TiO2@C were analyzed by X-ray diffraction (XRD). Both samples displayed a broad peak around 25° and a minor peak at 25.2° in their XRD patterns (Figure 4a). MH-TiO2@C exhibits all the peaks corresponding to the anatase phase of TiO2, indicating that the TiO2 layer formed TiO2 NPs with an anatase phase after calcination at 800 °C for 2 h in an N2 atmosphere [37]. After loading Pt NPs onto MH-TiO2@C, peaks corresponding to Pt (111), (200), and (220) were observed, confirming that the loaded Pt NPs adopt a face-centered cubic (fcc) structure [38]. The FWHM of the Ti (101) peak and Pt (111) peak of were fitted to calculate average grain sizes using the Scherrer formula. The calculated average grain sizes for TiO2 and Pt are 8.8 nm and 3.3 nm, respectively, which are consistent with the TEM results. Additionally, using the Bragg formula, the lattice spacings of the Pt (111) and TiO2 (101) crystal planes were calculated to be 0.227 nm and 0.355 nm, respectively, consistent with the IFFT analysis results. Compared to pure Pt, the slight shift in the (111) peak of Pt/MH-TiO2@C toward lower angle values is attributed to the SMSI effect, which leads to an increase in the Pt-Pt interatomic distance and a downward shift in the d-band center.
X-ray photoelectron spectroscopy (XPS) analysis was employed to investigate the surface composition and chemical states of Pt/MH-TiO2@C and MH-TiO2@C [39]. The survey spectra (Figure 4b) confirm the presence of C, Ti, and O in both samples, with Pt exclusively detected in Pt/MH-TiO2@C. High-resolution Ti 2p and Pt 4f spectra are shown in Figure 4c,d, respectively. After depositing Pt on MH-TiO2@C, the Ti 2p3/2 peak showed a positive shift of 0.37 eV (Figure 4c). In contrast, compared to commercial Pt/C (71.85 eV), the Pt 4f7/2 peak shifted to a lower binding energy (71.65 eV) (Figure 4d). These observations indicate electron transfer from Ti to Pt, confirming the SMSI between Pt and TiO2. The peak position shift also indicates that the center of the Pt d-band has shifted downward relative to the Fermi level, which is advantageous for optimizing Pt’s adsorption energy for small molecule adsorbents. This aligns with the principle that known SMSI can induce a downward shift in the Pt d-band center, weakening COads at active sites, thereby enhancing anti-poisoning competence and MOR activity. A slight widening of the FWHM of the Pt (Pt0, Pt2+) peak indicates a slight change in its coordination number, which is caused by the intermetallic bonding effect brought about by SMSI [40]. Additionally, SMSI stabilizes Pt NPs on the TiO2 surface, inhibiting decomposition and aggregation. These synergistic effects demonstrate that Pt/MH-TiO2@C exhibits superior MOR activity and durability compared to commercial Pt/C [41].
Figure 5a shows the cyclic voltammetry (CV) curves of the electrocatalysts in the solution of 1 M KOH, where the hydrogen desorption/adsorption peaks (0.05 to 0.4 V vs. RHE) were observed [26,42]. ECSAs were calculated according to the equation described in Supplemental Materials. The ECSA of Pt/MH-TiO2@C was 27.9 m2 gPt−1, slightly exceeding to that of Pt/C (26.4 m2 gPt−1). Notably, Pt/MH-TiO2@C shows an expanded electrochemical double-layer region compared to Pt/C, which can be attributed to the larger surface area of the mesoporous hollow MH-TiO2@C support relative to carbon black [43]. This high ECSA of Pt/MH-TiO2@C arises from two factors: (i) uniform Pt NPs dispersion enabled by strong Pt-TiO2 interactions (SMSI) and (ii) the mesoporous hollow architecture of MH-TiO2@C.
The electrochemical activities of the Pt/MH-TiO2@C and the commercial Pt/C toward MOR were recorded in the solution of N2-saturated 1 M KOH and 0.5 M CH3OH at 50 mV s−1. It can be clearly found that all electrocatalysts reveal two distinct oxidation peaks. The forward peak corresponds to the methanol oxidation on the Pt surface, while the backward peak presents the further oxidation of adsorbed carbonaceous intermediate species (e.g., CO) formed during the forward scan [2,44]. As we know, the performance of MOR can be reflected by the mass activity (MA, Figure 5b) and special activity (SA, Figure 5c) obtained by normalizing the peak current density of forward scan to the Pt loading on the disk electrode and Pt electrochemical active surface area, respectively. To obtain the real Pt loading, the Pt content in Pt/MH-TiO2@C was quantified using inductively coupled plasma-mass spectrometry (ICP-MS), revealing an actual loading of 38.43 wt% that closely matches the theoretical value of 40 wt% in synthesis process. It can be noticed that the Pt/MH-TiO2@C displays the enhanced MOR activity with MA of 5.53 A mgPt−1 and SA of 19.81 mA cm−2, which are 2.56-fold and 2.42-fold higher than those of commercial Pt/C (2.16 A mgPt−1, 8.18 mA cm−2), respectively, as shown in Figure 5d. The superior SA of Pt/MH-TiO2@C can be attributed to the increasing intrinsic activity and density of active sites, which result from SMSI between Pt and TiO2 and the unique properties of the composite MH-TiO2@C support. In order to investigate the charge transfer behavior of Pt/MH-TiO2@C during methanol oxidation, the electrochemical impedance spectra (EIS) were measured in the solution of 1 M KOH and 0.5 M CH3OH [45,46,47]. Data were modeled using a modified Randles equivalent circuit (Figure 5e). Critically, Pt/MH-TiO2@C shows a smaller high-frequency semicircle diameter with Rct of 2.2 Ω versus 3.9 Ω for commercial Pt/C, which indicates enhanced electrode/electrolyte interface kinetics, accelerating charge transfer and improving methanol oxidation efficiency. This can be attributed to the MHCS structure of Pt/MH-TiO2@C, that is, a three-dimensional conductive network that enables fast charge transfer. Finally, the MA of Pt/MH-TiO2@C toward MOR was compared with the state-of-the-art Pt-based electrocatalysts reported in other literature and the results are shown in Figure 5f and Table S3. Obviously, the Pt/MH-TiO2@C exhibits relatively high MA among the various electrocatalysts, indicating the efficient MOR electrocatalyst was successfully developed in this work [48,49,50,51,52,53,54,55,56]. This demonstrates potential for significant Pt reduction in practical applications while maintaining performance.
Durability is another important factor that affects the practical application of DMFCs. Chronoamperometry (CA) tests were performed in the solution of 1 M KOH and 0.5 M CH3OH at 0.83 V vs. RHE for 3600 s to evaluate the durability of Pt/MH-TiO2@C and commercial Pt/C. As illustrated in Figure 6a, both current densities decreased rapidly at the initial stage, and then gradually stabilized. The initial decrease is primarily attributed to the blockage and toxicity of adsorbed carbonaceous intermediates, such as COads and HCOOads, towards the Pt active sites [57]. Obviously, compared with Pt/C, the current density of Pt/MH-TiO2@C exhibited a markedly smaller decline during the initial stage, indicating its superior resistance to poisoning. Moreover, the current density of Pt/MH-TiO2@C consistently exceeds that of Pt/C. After 3600 s, the residual current density of Pt/MH-TiO2@C remained higher than that of Pt/C as well. Furthermore, the CV curves of Pt/MH-TiO2@C and Pt/C were again recorded after CA tests (Figure 6b,c). Although both Pt/MH-TiO2@C and Pt/C exhibit decreased MAs, the MA of Pt/C decreased from 2.16 to 1.03 A mgPt−1 (52.31% loss) after CA test, while Pt/MH-TiO2@C retained 3.82 A mgPt−1 from the initial 5.53 A mgPt−1 (30.92% loss) (Figure 6d). The decrease in SA followed identical trends, that is, Pt/MH-TiO2@C demonstrated a significantly lower degradation than Pt/C (Figure S3). These results indicate that the MOR durability of Pt/MH-TiO2@C is superior to that of Pt/C. In order to elucidate the reason for the superior durability of Pt/MH-TiO2@C, the aged Pt/MH-TiO2@C was collected and characterized by TEM. Figure S4 confirms the structural stability of Pt/MH-TiO2@C, demonstrating retention of the mesoporous hollow sphere morphology with negligible Pt NPs aggregation. The Pt NPs remained uniformly distributed, exhibiting only a marginal increase in mean particle size from 2.9 to 3.1 nm, which originates from SMSI between Pt and TiO2 that anchor the Pt NPs, and spatial confinement effects within the hollow architecture that suppress particle migration and coalescence. Hence, we inferred that besides the stable and novel mesoporous hollow structure, SMSI between Pt and TiO2 played an important role in the durability enhancement of Pt/MH-TiO2@C.

3. Experimental

3.1. Chemicals and Materials

Tetraethyl orthosilicate (TEOS, AR), tetrabutyl titanate (TBT, 98%), acetonitrile (CH3CN, 99.9%), absolute ethanol (EtOH, 99.7%), glucose (C6H12O6, AR), ammonia aqueous solution (NH3·H2O, 25.0~28.0%), sodium hydroxide (NaOH, 96.0%), methanol (CH3OH, 99.8%), chloroplatinic acid hexahydrate (H2PtCl6·6H2O, Pt ≥ 37.5%, 99.9%), formic acid (HCOOH, 98%), polytetrafluoroethylene emulsion (PTFE, 60 wt%), Nafion solution (5 wt%), and isopropanol (IPA, 99.7%). All chemicals in this study were purchased from Sinopharm Chemical Reagent Co., Ltd., Shanghai, China. Commercial Pt/C (40 wt%, HiSPEC 4000, Johnson Matthey, Shanghai, China) was purchased from SCI Material Hub. All materials and chemicals were used as received unless otherwise stated.

3.2. Synthesis of Pt/MH-TiO2@C Electrocatalyst

The synthesis of Pt/MH-TiO2@C electrocatalyst (Figure 7) comprises three key steps: (i) preparation of SiO2 NS templates via the Stöber method; (ii) sequential deposition of TiO2 and carbon layers on SiO2 NS templates, followed by template removal to obtain mesoporous hollow MH-TiO2@C supports; and (iii) deposition of Pt NPs on MH-TiO2@C using controlled formic acid reduction [58].
The typical Stöber method which was used to synthesize the SiO2 NS is described in elsewhere [59]. Briefly, TEOS was added dropwise to the base solution containing ethanol, DI water, and ammonia solution under continuous stirring. After 2 h reaction, the obtained milky suspension was centrifuged, washed at least 3 times with ethanol, and dried at 60 °C.
Subsequently, 200 mg of SiO2 NSs was dispersed in a mixture containing ethanol (100 mL), acetonitrile (30 mL), and ammonia (0.9 mL) via ultrasonication for 30 min. Tetrabutyl titanate (TBT, 0.75 mL) was then added dropwise to the mixture under continuous stirring for 3 h, followed by centrifugation and repeated washing with ethanol. The obtained SiO2@ TiO2 NSs underwent hydrothermal treatment in a Teflon-lined autoclave with glucose solution (0.2 M, 20 mL) at 180 °C for 5 h. After cooling to room temperature, the product (denoted SiO2@TiO2@C) was collected by centrifugation, washed with ethanol, and annealed at 800 °C for 3 h under N2 atmosphere (heating rate: 2 °C min−1). Template removal was achieved by etching the annealed product with 1 M NaOH aqueous solution for 12 h, followed by washing with DI water and ethanol to obtain MH-TiO2@C.
Finally, 35 mg MH-TiO2@C was dispersed in DI water (20 mL) via ultrasonication for 30 min. A predetermined amount of H2PtCl6·6H2O was added under vigorous stirring. Formic acid (1 mL) was introduced as reducing agent, and the mixture was maintained at 80 °C for 20 min. The resulting precipitate was alternately washed with DI water and ethanol three times, dried under vacuum at 80 °C for 12 h, yielding Pt/MH-TiO2@C with ~40 wt% Pt loading.

3.3. Physical Characterization

The crystal structure was characterized by XRD (Bruker D8 Advance, Bremen, Germany) with Cu Kα radiation (λ = 1.5406 Å) with a scan rate of 5° min−1 from 10° to 80°. The surface area and pore size distribution were analyzed via BET measurements using Autosorb-iQ MP analyzer (Quantachrome Instruments, Boynton Beach, FL, USA). The Morphology and elemental composition were examined by SEM (Hitachi SU8010) and TEM (Thermo Fisher Talos F200X, Waltham, MA, USA) equipped with EDS. The surface chemical states were investigated using XPS (Thermo Scientific ESCALAB Xi+, Waltham, MA, USA), with all binding energies referenced to the C 1s peak of graphitic carbon at 284.5 eV. The actual Pt loading was determined by ICP-MS (Thermo Fisher Scientific XSERIES 2, Waltham, MA, USA).

3.4. Electrochemical Measurement

All electrochemical measurements were performed with an electrochemical workstation (CHI760E, Shanghai Chenhua Instruments Co., Shanghai, China) through a three-electrode electrochemical cell, including a working electrode (glassy carbon electrode (GCE), 5 mm diameter), a reference electrode (Hg/HgO, 1 M KOH) and a counter electrode (Pt wire). All the measurements were carried out at room temperature. The working electrode was prepared as follows: 2 mg electrocatalyst was dispersed in a mixture consisting of 0.90 mL ethanol, 90 µL DI water and 10 µL 5 wt% Nafion, and further sonicated for 30 min, then 5 μL electrocatalyst ink was dripped on the polished GCE and dried naturally. The Pt loading on GCE was 20.38 µg cm−2. All potentials were referenced to RHE using the following equation:
ERHE = EHg/HgO + 0.098 V + 0.0592 × pH.
The ECSA of the electrocatalyst was determined by analyzing the CV curve, which was performed in a N2-saturated 1 M KOH solution at a scan rate of 50 mV s−1. The MOR activity was evaluated by conducting CV curve in a N2-saturated 1 M KOH and 0.5 M CH3OH solution at 50 mV s−1. EIS measurement was carried out in the frequency range of 1 Hz~100k Hz at a constant potential with an amplitude of 10 mV. Finally, CA test was performed at 0.83 V vs. RHE in the solution of 1 M KOH and 0.5 M CH3OH for 3600 s.

4. Conclusions

To address the electrocatalytic activity and durability limitations of commercial Pt/C towards MOR, we developed the SiO2-templated mesoporous hollow TiO2@carbon core–shell support for Pt-based electrocatalyst. The prepared Pt/MH-TiO2@C electrocatalyst exhibited superior MOR activity and durability in alkaline electrolyte. The MA and SA of Pt/MH-TiO2@C are 2.56-fold and 2.42-fold higher than those of commercial Pt/C, respectively. During CA tests, the current density of Pt/MH-TiO2@C consistently exceeded that of Pt/C. After CA tests, the MA of Pt/MH-TiO2@C decreased by 30.92%, which is much lower than that of commercial Pt/C (52.31%). The TEM analysis demonstrated that Pt/MH-TiO2@C maintained structural integrity with negligible Pt NP aggregation after CA test. Three synergistic mechanisms account for this enhanced MOR activity and durability: (i) the inherent stability of the MH-TiO2@C architecture, (ii) SMSI effect between TiO2 and Pt, and (iii) effective resistance towards MOR intermediates poisoning.

Supplementary Materials

The following supporting information can be downloaded at https://www.mdpi.com/article/10.3390/catal15090834/s1: Electrochemical surface area calculation; Scherrer formula and Bragg formula; Figure S1: SEM images of (a, b) SiO2 NSs, (c) SiO2@TiO2 NSs, (d) MH-TiO2@C NSs, and (e) EDS of MH-TiO2@C NSs; Figure S2: Line-scanning analysis of single Pt/MH-TiO2@C NS; Figure S3: Specific activity changes in Pt/MH-TiO2@C (a) and (b) Pt/C after CA tests; Figure S4: TEM images of single Pt/MH-TiO2@C NS and Pt particle size distribution diagram after CA test; Table S1: Surface areas and pore structure properties from BET analysis of SiO2@TiO2@C and MH-TiO2@C; Table S2: Electrochemical tests data of Pt/MH-TiO2@C and commercial Pt/C before and after CA tests; Table S3: Comparison of the Pt/MH-TiO2@C with other electrocatalysts reported in recent studies on MOR activity in alkaline electrolyte. The Supplementary Materials contain 9 references [48,49,50,51,52,53,54,55,56].

Author Contributions

Conceptualization, Y.C., Q.M., H.S. and Q.X.; data curation, Y.C., Z.L., M.L. and H.S.; formal analysis, Y.C., H.L. and W.Z.; funding acquisition, Q.M. and Q.X.; investigation, Y.C. and H.L.; methodology, Y.C., Q.M., M.L. and W.Z.; resources, Z.L.; supervision, W.Z. and Q.X.; writing—original draft, Y.C.; writing—review and editing, Q.X. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by the National Natural Science Foundation of China (No. 52276066), the Natural Science Foundation of Jiangsu Province (No. BK20231323), the Foundation of Key Laboratory of Power Machinery and Engineering, Ministry of Education, Shanghai Jiao Tong University (No. 202306), and the Research Fund Program of Key Laboratory of Advanced Electrode Materials for Novel Solar Cells for Petroleum and Chemical Industry of China (No. 2024A058).

Data Availability Statement

The data are contained within the article and Supplementary Materials.

Conflicts of Interest

The authors declare no conflicts of interest.

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Figure 1. SEM images of (a) SiO2@TiO2 NSs; (b) MH-TiO2@C NSs; (c) N2 adsorption isotherms; and (d) pore size distribution curves of SiO2@TiO2@C and MH-TiO2@C.
Figure 1. SEM images of (a) SiO2@TiO2 NSs; (b) MH-TiO2@C NSs; (c) N2 adsorption isotherms; and (d) pore size distribution curves of SiO2@TiO2@C and MH-TiO2@C.
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Figure 2. (a–c) SEM images of Pt/MH-TiO2@C electrocatalyst. (d) EDS elemental mappings of Pt, C, Ti, and O.
Figure 2. (a–c) SEM images of Pt/MH-TiO2@C electrocatalyst. (d) EDS elemental mappings of Pt, C, Ti, and O.
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Figure 3. (a–c) TEM images of Pt/MH-TiO2@C. (inset of c) size analysis of Pt NPs. Corresponding (e) FFT images of the yellow box region in (d). (Inset of e) IFFT images. Corresponding (g) FFT images of the yellow box region in (f). (Inset of g) IFFT images. (h) HAADF-STEM image and elemental mappings of single Pt/MH-TiO2@C NS.
Figure 3. (a–c) TEM images of Pt/MH-TiO2@C. (inset of c) size analysis of Pt NPs. Corresponding (e) FFT images of the yellow box region in (d). (Inset of e) IFFT images. Corresponding (g) FFT images of the yellow box region in (f). (Inset of g) IFFT images. (h) HAADF-STEM image and elemental mappings of single Pt/MH-TiO2@C NS.
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Figure 4. (a) XRD patterns. (b) XPS survey spectra. High-resolution spectra of (c) Ti 2p and (d) Pt 4f of MH-TiO2@C, Pt/MH-TiO2@C, and Pt/C.
Figure 4. (a) XRD patterns. (b) XPS survey spectra. High-resolution spectra of (c) Ti 2p and (d) Pt 4f of MH-TiO2@C, Pt/MH-TiO2@C, and Pt/C.
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Figure 5. MOR activities of Pt/MH-TiO2@C and Pt/C. (a) CV curves of Pt/C and Pt/MH-TiO2@C in N2-saturated solution containing 1 M KOH. (b) Mass activity. (c) Specific activity. (d) Comparison of MOR activities of Pt/C and Pt/MH-TiO2@C. (e) EIS Nyquist spectra of Pt/C and Pt/MH-TiO2@C with the frequency range of 1 Hz–100k Hz. (f) Comparison of the Pt/MH-TiO2@C with other electrocatalysts reported in the recent literature for MOR activity in alkaline electrolyte.
Figure 5. MOR activities of Pt/MH-TiO2@C and Pt/C. (a) CV curves of Pt/C and Pt/MH-TiO2@C in N2-saturated solution containing 1 M KOH. (b) Mass activity. (c) Specific activity. (d) Comparison of MOR activities of Pt/C and Pt/MH-TiO2@C. (e) EIS Nyquist spectra of Pt/C and Pt/MH-TiO2@C with the frequency range of 1 Hz–100k Hz. (f) Comparison of the Pt/MH-TiO2@C with other electrocatalysts reported in the recent literature for MOR activity in alkaline electrolyte.
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Figure 6. (a) CA curves recorded at a constant potential of 0.83 V vs. RHE for 3600 s in N2-saturated solution containing 1 M KOH and 0.5 M CH3OH. CV curves of (b) Pt/MH-TiO2@C and (c) Pt/C before and after CA tests. (d) MA variations in Pt/C and Pt/MH-TiO2@C.
Figure 6. (a) CA curves recorded at a constant potential of 0.83 V vs. RHE for 3600 s in N2-saturated solution containing 1 M KOH and 0.5 M CH3OH. CV curves of (b) Pt/MH-TiO2@C and (c) Pt/C before and after CA tests. (d) MA variations in Pt/C and Pt/MH-TiO2@C.
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Figure 7. Schematic illustration of the synthesis of Pt/MH-TiO2@C electrocatalyst.
Figure 7. Schematic illustration of the synthesis of Pt/MH-TiO2@C electrocatalyst.
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Chen, Y.; Liu, H.; Ma, Q.; Li, Z.; Lu, M.; Su, H.; Zhang, W.; Xu, Q. Pt Nanoparticles Supported on Mesoporous Hollow TiO2@C Sphere Composite as Efficient Methanol Oxidation Reaction Electrocatalysts. Catalysts 2025, 15, 834. https://doi.org/10.3390/catal15090834

AMA Style

Chen Y, Liu H, Ma Q, Li Z, Lu M, Su H, Zhang W, Xu Q. Pt Nanoparticles Supported on Mesoporous Hollow TiO2@C Sphere Composite as Efficient Methanol Oxidation Reaction Electrocatalysts. Catalysts. 2025; 15(9):834. https://doi.org/10.3390/catal15090834

Chicago/Turabian Style

Chen, Yuan, Huiyuan Liu, Qiang Ma, Zhuo Li, Mengyue Lu, Huaneng Su, Weiqi Zhang, and Qian Xu. 2025. "Pt Nanoparticles Supported on Mesoporous Hollow TiO2@C Sphere Composite as Efficient Methanol Oxidation Reaction Electrocatalysts" Catalysts 15, no. 9: 834. https://doi.org/10.3390/catal15090834

APA Style

Chen, Y., Liu, H., Ma, Q., Li, Z., Lu, M., Su, H., Zhang, W., & Xu, Q. (2025). Pt Nanoparticles Supported on Mesoporous Hollow TiO2@C Sphere Composite as Efficient Methanol Oxidation Reaction Electrocatalysts. Catalysts, 15(9), 834. https://doi.org/10.3390/catal15090834

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