Search Results (142)

Surface and sub-surface atomic configurations are critical for catalysis as they host the active sites governing electrochemical processes. This study employs density functional theory (DFT) calculations and Monte Carlo simulations combined with the cluster-expansion approach to investigate atom distribution and Pt segregation in Pt-Fe alloys across varying Pt/Fe ratios. Our simulations reveal a strong tendency for Pt atoms to segregate to the surface layer while Fe atoms enrich the sub-surface region. Crucially, the calculations predict the stability of a periodic Pt₂Fe alloy surface model, characterized by specific defect structures, at low platinum content and low annealing temperatures. Electronic structure analysis indicates that forming this Pt₂Fe surface alloy lowers the d-band center of Pt atoms, weakening CO adsorption and thereby enhancing resistance to CO poisoning. Although defect-induced strains can modulate the d-band center, crystal orbital Hamilton population (COHP) analysis confirms that such strains generally strengthen Pt-CO interactions. Therefore, the theoretical design of Pt₂Fe alloy surfaces and controlling defect density are predicted to be effective strategies for enhancing catalyst resistance to CO poisoning. This work highlights the advantages of periodic Pt₂Fe surface models for anti-CO poisoning and provides computational guidance for designing efficient Pt-based electrocatalysts. Full article

The degradation of electrochemical materials during energy conversion and storage, in particular the electrocatalyst materials, is becoming increasingly important. The selection and design of sustainable materials is an important task. This work examines the synthesis, characterization, and application of an electrocatalyst (based on an amorphous alloy Co75Si15Fe5Cr4.5) having a structured surface in the form of nanocells for a “green” nitrate reduction reaction (NO₃RR), which can serve as an alternative to the well-known Haber-Bosch process for the synthesis of ammonia. The material for the electrocatalyst was obtained by anodizing the alloy in the ionic liquid BmimNTf₂ and characterized by using a combination of modern physicochemical and electrochemical methods. The Faradaic efficiency (FE) for the nanocell catalyst exceeds by more than three-fold and seven-fold catalyst with a polished surface and the initial catalyst having a natural oxide on the surface, respectively. A mechanism of this reaction on the studied electrocatalysts with structured and non-structured surfaces is proposed. It is mentioned that the nanocell electrocatalyst is an extremely stable material that passes all tests without visible changes. The authors consider their work as a starting point for the application of a nanostructured Co-electrocatalyst in NO₃RR. Full article

The development of efficient platinum group metal-free (PGM-free) catalysts for the hydrogen evolution reaction (HER) and the hydrogen oxidation reaction (HOR) is essential for advancing hydrogen-based energy technologies. In this study, Ni_xMo_100−x composites supported on Carbon Ketjenblack EC-300J (CK) were synthesized via thermal reduction under a controlled Ar/H₂ (95:5) atmosphere to investigate the effect of the Ni/Mo molar ratio on electrocatalytic performance. Structural and morphological analyses by XRD and TEM confirmed the formation of the NiMo alloys and carbide phases with controlled particle size distributions (~18 nm), while BET measurements revealed specific surface areas up to 124.69 m² g⁻¹ for the Pt-loaded samples. Notably, the 3% Pt/Ni₉₀Mo₁₀-CK catalyst exhibited outstanding bifunctional activity in a half-cell configuration, achieving an overpotential of 65.2 mV and a Tafel slope of 41.6 mV dec⁻¹ for the HER, and a Tafel slope of 32.9 mV dec⁻¹ with an exchange current density of 1.03 mA cm⁻² for the HOR. These results demonstrate that compositional tuning and minimal Pt incorporation synergistically enhance the catalytic efficiency, providing a promising platform for next-generation hydrogen electrocatalysts. Full article

This report introduces a high-performance bimetallic electrocatalyst for the oxygen reduction reaction (ORR) featuring a 20 wt.% platinum content. The PtCu-based catalyst combines de-alloyed nanoparticles (NPs) supported on nitrogen-doped carbon. Enhanced uniformity in NP distribution significantly boosts the catalyst performance. Nitrogen-doped carbon provides active centers for NP deposition, which is confirmed by HAADF-STEM and EDX. The PtCu/CN catalyst achieves over 5.6 times the ORR mass activity and two times the stability under pulse cycling compared to commercial Pt/C. Uniquely, the study examines bimetallic NPs and local nano-sites before and after stress testing using IL-TEM. In situ analysis of PtCu/CN microstructure revealed two primary degradation mechanisms, (i) partial dissolution of NPs and (ii) NP agglomeration, with the C–N support significantly mitigating these effects through strong NP–support interactions. The findings underscore the prospects of bimetallic PtCu catalysts with nitrogen-doped support by showcasing exceptional ORR activity and durability. Full article

Electrochemical nitrogen reduction reaction (NRR) has emerged as a promising approach for sustainable ammonia synthesis under ambient conditions, offering a low-energy alternative to the traditional Haber–Bosch process. However, the development of efficient and sustainable electrocatalysts for NRR remains a significant challenge. Noble metals, known for their exceptional chemical stability under electrocatalytic conditions, have garnered considerable attention in this field. In this study, we report the successful synthesis of nanoporous CuAuPtPd quasi-high-entropy alloy (quasi-HEA) prism arrays through “melt quenching” and “dealloying” techniques. The as-obtained alloy demonstrates remarkable performance as an NRR electrocatalyst, achieving an impressive ammonia synthesis rate of 17.5 μg h⁻¹ mg⁻¹ at a potential of −0.2 V vs. RHE, surpassing many previously reported NRR catalysts. This work not only highlights the potential of quasi-HEAs as advanced NRR electrocatalysts but also provides valuable insights into the design of nanoporous multicomponent materials for sustainable energy and catalytic applications. Full article

Quaternary NiCoMoB electrocatalysts exhibited significantly enhanced OER performance compared to their ternary NiCoMo and NiCoB counterparts. An optimal Mo/B ratio of 1 (NiCoMo_yB_y) demonstrated a superior OER activity, attributed to a balance between the electronic and structural contributions from Mo and B, maximizing the electrocatalytic site density and activity. NiCoMo_yB_y-SA, a nanoparticle version synthesized via a surfactant-assisted method, showed further improved performance. The OER activity was evaluated by comparing overpotentials at 10 mA/cm², with NiCoMo_xB_1−x, NiCoMo_yB_y, and NiCoMo_yB_y-SA exhibiting 293, 284, and 270 mV, respectively. NiCoMo_yB_y-SA also demonstrated the lowest onset potential (1.45 V), reflecting a superior efficiency. Chronoamperometry in 1 M pre-electrolyzed KOH at 30 °C highlighted NiCoMo_yB_y-SA’s stability, activating within hours at 10 mA/cm² and stabilizing over 7 days. At 50 mA/cm², the overpotential increased minimally (0.02 mV/h over 2 days), and even at 100 mA/cm² for 10 days, the activity declined only slightly, affirming a high stability. These findings demonstrate NiCoMoB electrocatalysts as cost-effective, efficient OER electrocatalysts, advancing sustainable energy technologies. Full article

The electrochemical reduction of carbon dioxide (CO₂RR) utilizing intermittent electricity from renewable energy sources represents an emerging and promising approach to achieve carbon neutrality and mitigate the greenhouse effect. This review comprehensively summarizes recent advances in Cu-based metal–organic framework (MOF) electrocatalysts for CO₂RR, focusing on their applications in producing C₁ and C₂₊ products. This paper highlights key strategies such as nanostructure manipulation, multi-component tandem catalysis, single-atom alloying, and ligand functionalization to optimize the binding energies of intermediate species and promote selective CO₂RR pathways. Numerous examples are presented, showcasing remarkable Faradaic efficiencies and product selectivities achieved through rational catalyst design. Furthermore, the use of MOF-derived materials and composites with other materials, like carbon nanotubes, graphene, and metal oxides, is discussed to enhance conductivity, stability, and selectivity. Despite the significant progress, challenges remain in achieving stable and scalable catalysts with high activity and selectivity towards specific C₂₊ products. This review underscores the importance of precise control of catalyst composition, structure, and surface properties to tackle these challenges and provides valuable insights for future research directions in developing advanced Cu-based MOF electrocatalysts for practical applications in CO₂ conversion technologies. Full article

The development of advanced electrocatalysts plays a pivotal role in enhancing hydrogen production through water electrolysis. In this study, we employed a two-step electrodeposition method to fabricate a 3D porous Cu-Co-Ni alloy with superior catalytic properties and long-term stability for hydrogen evolution reaction (HER). The resulting trimetallic alloy, Cu@Cu-Ni-Co, demonstrated significant improvements in structural integrity and catalytic performance. A comparative analysis of electrocatalysts, including Cu, Cu@Ni-Co, and Cu@Cu-Ni-Co, revealed that Cu@Cu-Ni-Co achieved the best results in alkaline media. Electrochemical tests conducted in 1.0 M NaOH showed that Cu@Cu-Ni-Co reached a current density of 10 mA cm⁻² at a low overpotential of 125 mV, along with a low Tafel slope of 79.1 mV dec⁻¹. The catalyst showed exceptional durability, retaining ~95% of its initial current density after 120 h of continuous operation at high current densities. Structural analysis confirmed that the enhanced catalytic performance arises from the synergistic interaction between Cu, Ni, and Co within the well-integrated trimetallic framework. This integration results in a large electrochemical active surface area (ECSA) of 380 cm² and a low charge transfer resistance (15.76 Ω), facilitating efficient electron transfer and promoting superior HER activity. These findings position Cu@Cu-Ni-Co as a highly efficient and stable electrocatalyst for alkaline HER in alkaline conditions. Full article

Developing cost-effective and high-performance non-precious metal-based electrocatalysts for hydrogen evolution reaction is of crucial importance toward sustainable hydrogen energy systems. Herein, we prepare a novel hybrid electrode featuring intermetallic Fe₂Mo nanoparticles anchored on the hierarchical nanoporous copper skeleton as robust hydrogen evolution electrocatalyst by simple and scalable alloying and dealloying methods. By virtue of the highly active intermetallic Fe₂Mo nanoparticles and unique bicontinuous nanoporous copper skeleton facilitating ion/molecule transportation, nanoporous Fe₂Mo/Cu electrode shows excellent hydrogen evolution reaction electrocatalysis, with a low Tafel slope (~71 mV dec⁻¹) to realize ampere-level current density of 1 A cm⁻² at a low overpotential of ~200 mV in 1 M KOH electrolyte. Furthermore, nanoporous Fe₂Mo/Cu electrode exhibits long−term stability exceeding 400 h to maintain ~250 mA cm⁻² at an overpotential of 150 mV. Such outstanding electrocatalytic performance enables the nanoporous Fe₂Mo/Cu electrode to be an attractive hydrogen evolution reaction catalyst for water splitting in the hydrogen economy. Full article

Cyclic voltammetry (CV) is one of the advanced techniques used to determine various bioactive molecules, organic dyes, pesticides, veterinary drugs, heavy metals, toxic chemicals, etc. To determine all the above analytes, one needs an electrocatalyst for their electrochemical redox reaction. Many researchers have reported the use of metal nanomaterials, metal oxide nanomaterials, metal–organic frameworks, surfactants, polymers, etc., as modifiers in carbon paste electrodes to enhance their current response, stability, sensitivity, and repeatability. But some of the emerging, cost-effective, and highly efficient electrocatalysts are advanced nanostructured alloy powders. These advanced alloys are used as a modifier to determine various bioactive analytes. These alloy-modified carbon paste electrodes (MCPEs) show excellent selectivity, sensitivity, and stability due to their extraordinary electrochemical properties, as the compositional elements of most of the alloys belong to d-block elements in the periodic table, and these transition elements are famous for their brilliant electrocatalytic properties. The present review article mainly focuses on the determination of dopamine, AA (AA), uric acid, methylene blue, methyl orange, Rhodamine B, and the L-Tyrosine amino acid by various alloys like stainless steel, high-entropy alloys, and shape-memory alloys and how these alloys could change the perception of metallurgists and electrochemists in the future. These alloys could be potential candidates for the development of various electrochemical sensors because of their high porosity and surface areas. Full article

In recent years, the electrochemical conversion of CO₂ gasses into renewable fuels (e.g., ethylene, ethanol, and propanol) has attracted much attention. In this process, electrocatalysts play a crucial role in accelerating the CO₂ reduction reaction (CO₂RR) process. In this review, the role of electrocatalysts in the synthesis of C₂₊ products (e.g., ethanol, ethylene, and propanol) from CO₂ was investigated. To this end, various classifications of electrocatalysts such as metals, metal oxides, metal alloys, covalent organic frameworks (COFs), carbon-based electrocatalysts, and metal–organic frameworks (MOFs) and their utilization in CO₂ conversion into C₂₊ chemicals were fully investigated. Also, the impact of various factors such as catalyst stability, temperature, membrane type, pressure, current density, pH, and the type of electrolyte on the CO₂RR process to generate C₂₊ valuable products was investigated. Moreover, the mechanism of this process for producing renewable fuels was investigated. Furthermore, the limitations and future perspective of CO₂RR were surveyed. Finally, the industrial application of this process for producing value-added products was investigated. Based on our investigation, Cu and Cu₂O-based electrocatalysts are suitable catalysts for C₂₊ products, particularly ethylene and ethanol. Full article

Fuel cells/zinc–air cells represent a transformative technology for clean energy conversion, offering substantial environmental benefits and exceptional theoretical efficiency. However, the high cost and limited durability of platinum-based catalysts for the sluggish oxygen reduction reaction (ORR) at the cathode severely restrict their scalability and practical application. To address these critical challenges, this study explores a groundbreaking approach to developing ORR catalysts with enhanced performance and reduced costs. We present a novel Pd₃Cu alloy, innovatively modified with N-doped carbon aerogels, synthesized via a simple self-assembly and freeze-drying method. The three-dimensional carbon aerogel-based porous structures provide diffusion channels for oxygen molecules, excellent electrical conductivity, and abundant ORR reaction sites. The Pd₃Cu@2NC-20% aerogel exhibits a remarkable enhancement in ORR activity, achieving a half-wave potential of 0.925 V, a limiting current density of 6.12 mA/cm², and excellent long-term stability. Density functional theory (DFT) calculations reveal that electrons tend to transfer from the Pd atoms to the neighboring *O, leading to an increase in the negative charge around the *O. This, in turn, weakens the interaction between the catalyst surface and the *O and optimizes the elementary steps of the ORR process. Full article

The search for cost-effective and scalable electrocatalysts for the hydrogen evolution reaction (HER) remains a critical challenge in advancing sustainable energy technologies. This study presents a novel approach to optimizing nickel-iron (Ni-Fe) alloy coatings on graphite (G) electrodes through a strategic combination of composition tuning, nickel modification, and various electrochemical optimizations. Unlike conventional studies, which primarily focus on static alloy compositions, this work systematically investigates the impact of dynamic nickel modification durations on the catalytic performance and conductivity of Ni-Fe alloys. By addressing the conductivity limitations caused by iron oxidation, the study demonstrates the enhanced HER kinetics achieved with a Ni-modified G/Ni_%95Fe_%5-Ni(60s) electrode. Electrochemical and structural analyses reveal the synergistic effects of nickel modifications on improving active site accessibility, reducing overpotential, and increasing hydrogen production efficiency. This work introduces a scalable methodology for tailoring Ni-Fe catalysts, offering significant advancements in the development of robust, cost-effective electrocatalysts for industrial-scale hydrogen production. Full article

A sustainable reaction of electrocatalytic nitrate conversion in ammonia production (NO₃RR) occurring under ambient conditions is currently of prime interest, as well as urgent research due to the real potential replacement of the environmentally unfavorable Haber–Bosch process. Herein, a series of electrocatalysts based on two-component cobalt alloys was synthesized using low-cost non-noble metals Co, Fe, Cr, and also Si. The samples of electrocatalysts were characterized and studied by the following methods: SEM, EDX, XRD (both transmission and reflection), UV–VIS spectroscopy, optical microscopy, linear (and cyclic) voltammetry, chronoamperometry, and electrochemical impedance spectroscopy. Beyond that, the determination of electrochemically active surface area was also carried out for all samples of electrocatalysts. Unexpectedly, the sample having an intermetallic compound (IMC) of the composition Co₂Si turned out to be the most highly effective. The highest Faradaic efficiency (FE) of 80.8% at E = −0.585 V (RHE) and an ammonia yield rate of 22.3 µmol h⁻¹ cm⁻² at E = −0.685 V (RHE) indicate the progressive role of IMC as the main active component of the electrocatalyst. Thus, this study demonstrates the promise and enormous potential of IMC as the main component of highly efficient electrocatalysts for NO₃RR. This work can serve primarily as a starting point for future studies of electrocatalytic conversion reactions in the production of ammonia using IMC catalysts containing non-noble metals. Full article

Single-atom catalysts (SACs) are presently recognized as cutting-edge heterogeneous catalysts for electrochemical applications because of their nearly 100% utilization of active metal atoms and having well-defined active sites. In this regard, SACs are considered renowned electrocatalysts for electrocatalytic O₂ reduction reaction (ORR), O₂ evolution reaction (OER), H₂ evolution reaction (HER), water splitting, CO₂ reduction reaction (CO₂RR), N₂ reduction reaction (NRR), and NO₃ reduction reaction (NO₃RR). Extensive research has been carried out to strategically design and produce affordable, efficient, and durable SACs for electrocatalysis. Meanwhile, persistent efforts have been conducted to acquire insights into the structural and electronic properties of SACs when stabilized on an adequate matrix for electrocatalytic reactions. We present a thorough and evaluative review that begins with a comprehensive analysis of the various substrates, such as carbon substrate, metal oxide substrate, alloy-based substrate, transition metal dichalcogenides (TMD)-based substrate, MXenes substrate, and MOF substrate, along with their metal-support interaction (MSI), stabilization, and coordination environment (CE), highlighting the notable contribution of support, which influences their electrocatalytic performance. We discuss a variety of synthetic methods, including bottom-up strategies like impregnation, pyrolysis, ion exchange, atomic layer deposition (ALD), and electrochemical deposition, as well as top-down strategies like host-guest, atom trapping, ball milling, chemical vapor deposition (CVD), and abrasion. We also discuss how diverse regulatory strategies, including morphology and vacancy engineering, heteroatom doping, facet engineering, and crystallinity management, affect various electrocatalytic reactions in these supports. Lastly, the pivotal obstacles and opportunities in using SACs for electrocatalytic processes, along with fundamental principles for developing fascinating SACs with outstanding reactivity, selectivity, and stability, have been highlighted. Full article