Electrocatalysts For Methanol Oxidation Reaction Research Articles

Facile synthesis of green graphite-based (Ni/Cu/N) MOF composite for a methanol oxidation reaction

Recently, direct methanol fuel cells (DMFCs) have been regarded as the greatest energy-producing owing to their low operating temperature, high production rate of methanol, and low greenhouse gas emission. However, the energy conversion efficiency of the DMFCs is still unsatisfactory due to the slow kinetics of the fuel oxidation reaction. So, an economic electrocatalyst with high efficiency and good stability is still needed. Herein, low-cost nanocomposites of (Ni/Cu/N) MOF and palm pollen-derived G-graphite were prepared with different ratios namely, (1:1), (1:2), and (2:1) through a solvothermal reaction. The nanocomposites were characterized via X-ray diffraction (XRD), Scanning electron Microscopy (SEM), Fourier transform infrared (FTIR), Thermal gravimetric analysis (TGA), and, (Brunauer–Emmett–Teller) technique (BET). Electrodes have been tested as electro-catalysts for methanol-oxidation reaction (MOR) in a basic medium. As revealed from the cyclic voltammetry measurements, all electrodes exhibit a good response to MOR, being the nanocomposite with the ratio between (Ni/Cu/N) MOF and G-graphite (2:1) is the best with an oxidation peak current density of 55 mA/cm2 at a scan rate of 50 mV/s, with an onset potential of 0.35 V, and stability reaches 96 %. The electrochemical impedance spectroscopy (EIS) test showed that the ratio (2:1) has the lowest charge transfer resistance, RCT, of 5.21 Ω which confirms its higher electrochemical activity. This superior performance of the (Ni/Cu/N) MOF and G-graphite (2:1) over other reported MOF-based electrocatalysts is attributed to the synergistic effect of the (Ni/Cu/N) MOF electrocatalyst, wherein Ni and Cu provide redox electrocatalytic active sites for MOR while the G-graphite contributes towards the chemical stability and electrical conductivity of the electrode, respectively. The good activity and stability of the prepared electrodes suggest the potential use of these electrodes as electrocatalysts for MOR in direct methanol fuel cells (DMFCs).This study opens the venue for valorizing the natural wastes derived graphitic material as stable supporting material in Mof based composites electrodes for MOR.

Metal Organic Frameworks‐Derived NiO/NiCo2O4 Heterostructures for Effective Methanol Oxidation Reaction

AbstractThe electrochemical process of methanol oxidation reaction (MOR), which is closely associated with electrochemical production of formate and hydrogen, is considered a highly viable avenue for advancing renewable energy technologies. Nevertheless, the development and creation of affordable, effective, and durable electrocatalysts for MOR continue to present significant obstacles. In this study, a hierarchical porous NiO/NiCo2O4/NF electrode is fabricated through the integration of solvothermal and thermal oxidation treatments of Ni‐MOF‐74 and NiCo‐Asp. After thoroughly assessing the electrochemical performance for MOR, NiO/NiCo2O4/NF demonstrates a significant current density of 140 mA cm−2 at 1.6 V (vs. RHE) and a tafel slop of 45.0 mV·dec−1 in 1 M KOH and 0.5 M methanol. The excellent performance of MOR can be ascribed to the hierarchical porous nature that enhances mass and electron transport while offering numerous active sites for electrocatalytic reactions. Additionally, the hetero interface between NiO and NiCo2O4 could further enhance electron transfer rate and reaction kinetics for the MOR. The developed NiO/NiCo2O4/NF electrode shows potential as a viable and economical alternative to Pt‐based electrocatalysts for MOR‐based applications.

Hollow structured Co3O4/CuO nanocomposite as an efficient electrocatalyst for methanol oxidation reaction

In this work, a series of Co3O4/CuO nanocomposites with different component ratios are successfully synthesized by simple and economical hydrothermal and calcination methods, using nickel foam as the substrate. The catalytic performances of nickel foam supported Co3O4/CuO nanocomposites for methanol oxidation reaction (MOR) are evaluated. TEM characterization shows that the Co3O4/CuO nanocomposites have a hollow framework structure. The electrocatalytic test results prove the catalytic performance of the Co3O4/CuO nanocomposites is observably better than that of Co3O4 and CuO. Among the Co3O4/CuO nanocomposites, the CoCu-5 with a CuO content of 49.76 % has the highest catalytic activity and good stability. The current density value of CoCu-5 can reach 193.8 mA mg−1 at 0.6 V (vs Ag/AgCl), and the current density retention ratio is 93.8 % after 1000 CV cycles of testing. The excellent electrocatalytic performance of the Co3O4/CuO nanocomposites can be due to the synergistic effect between Co3O4 and CuO, and the large number of catalytic active sites brought about by the unique hollow frame structure.

Palladium nanoparticles incorporated biogenic modified graphitic carbon nitride as an electrocatalyst for methanol oxidation reaction

This research explores palladium (Pd) nanoparticles supported on graphitic carbonitride (g-C3N4) as a cost-effective and CO tolerant catalyst towards electrocatalytic methanol oxidation reaction (MOR). The study delves into the green synthesis strategy, employing phytochemicals as reducing, capping and stabilizing agents. This approach aligns with environmentally friendly practices, steering away from hazardous chemicals and solvents commonly used in traditional synthesis methods. The synthesis involves the dispersion of Pd nanoparticles supported on graphitic carbon nitride (g-C3N4) modified by banana leaf extract [PdNPs@g-C3N4-BLE]. The obtained nanocatalyst is characterized using various spectroscopic and microscopic techniques. Further, the synthesized PdNPs@g-C3N4-BLE is utilized as electrocatalyst for methanol oxidation reaction (MOR) in basic medium (1 M KOH). PdNPs@g-C3N4-BLE shows satisfactory activity towards MOR with an onset potential of 0.834 V and current density of 6.795 mA/cm2 at 1.0 V.

2H‐Au Nanosheet‐Templated Growth of PdFe for Electrocatalytic Methanol Oxidation

AbstractPd‐based alloy nanomaterials normally crystallize in the conventional face‐centered cubic (fcc) crystal phase. Here, 2H‐Au nanosheets (NSs), possessing 2H crystal phase (2H: hexagonal close‐packed with a stacking sequence of “AB”), are used as templates for the growth of PdFe, during which the 2H‐to‐fcc phase transformation in Au NSs happens, leading to the formation of 2H/fcc Au@PdFe core–shell NSs. By changing the Pd/Fe atomic ratio, the 2H/fcc phase ratio in 2H/fcc Au@PdFe NSs can be tuned accordingly. As a proof‐of‐concept application, the as‐synthesized 2H/fcc Au@Pd0.66Fe0.34 NSs are used as an electrocatalyst for methanol oxidation reaction (MOR) in alkaline media, exhibiting a remarkable mass activity of 4.39 A mg−1Pd, which is 1.7, 5.4 and 12.9 times that of 2H/fcc Au@Pd0.56Fe0.44 NSs (2.57 A mg−1Pd), 2H/fcc Au@Pd0.40Fe0.60 NSs (0.81 A mg−1Pd), and Pd black (0.34 A mg−1Pd), respectively, placing it among the best of reported Pd‐based MOR electrocatalysts. This strategy, based on phase engineering of nanomaterials (PEN), paves an efficient way to the rational design and controlled synthesis of noble multimetallic nanostructures with unconventional phases for exploring the phase‐dependent properties and applications.

Trimetallic Ni-CuCoN0.6 Ohmic junction for the enhanced oxidation of methanol and urea

Methanol oxidation reaction (MOR) and urea oxidation reaction (UOR) can be utilized as effective alternatives to the anodic oxygen evolution reaction (OER) in overall water-splitting. Nevertheless, the development of cost-effective, highly efficient and durable electrocatalysts for MOR and UOR remains a significant challenge. Herein, the Ohmic junction (Ni-CuCoN0.6@CC) comprising CuCoN0.6 nanosheets and Ni nanoparticles anchored on carbon cloth (CC) was successfully synthesized via a two-step hydrothermal process followed by pyrolysis. The Ni-CuCoN0.6@CC demonstrates exceptional performance in both MOR (1.334 V@10 mA cm−2) and UOR (1.335 V@10 mA cm−2), coupled with outstanding durability, maintaining 88.70 % current density for MOR and 88.92 % for UOR after a rigorous 50-h stability test. Furthermore, the Ni-CuCoN0.6@CC demonstrates a high selectivity for oxidizing methanol to formic acid, achieving Faraday efficiencies exceeding 90 % at various current densities in the context of MOR. The outstanding performance of Ni-CuCoN0.6@CC in terms of MOR and UOR either surpasses or closely approaches the levels reported in previous literature, primarily due to the synergistic effect resulting from the Ohmic junction: in this system, Ni serves as the principal active component, Co augments catalytic activity and diminishes onset potential, while Cu enhances long-term durability. Moreover, CuCoN0.6 nanosheets effectively modulate electronic structure and optimize the morphology of Ni, leading to the exposure of numerous defects that provide a wealth of active sites for the reaction. Additionally, the exceptional hydrophilic and aerophobic surface promotes enhanced mass transfer. Density functional theory (DFT) calculations show that Ni-CuCoN0.6@CC enhances reactant adsorption and product desorption, reducing energy barriers and expediting MOR and UOR kinetics.

Insights into the roles of nitrogen and phosphorus co-doping for efficient methanol electrooxidation

Anchoring Pt onto multi-heteroatom doped carbon materials has been recognized as an effective approach to improve the performance of electrocatalytic methanol oxidation. However, distinct contributions and specific behavior mechanisms of different heteroatoms, notably N and P, the specific behavior mechanisms in synergistically promoting Pt NPs remain elusive. In this work, we construct 1D N and P co-doped carbon nanotube (N, P-CNTs) supports with abundant defect anchors for Pt. The as-prepared Pt/N, P-CNTs exhibit outstanding activity and exceptional stability in methanol oxidation reaction (MOR), achieving high mass activity up to 6481.3 mA mg−1Pt. Moreover, they can retain 90.5 % of their initial current density even after 800 cycles tests. Detailed characterizations and theoretical calculations indicate that the robust strong metal-support interactions (SMSI) effect caused by N doping within the unique N and P co-doped coordination structure controllably regulate the coordination environment of Pt, reduce the d-band center of Pt, thus promoting the adsorption and decomposition of CH3OH. However, P doping weakens the adsorption strength of CO on the Pt active site by sacrificing partial electron transfer, accelerating the oxidative conversion of the CO-like poisoning species (COads). Significantly, the synergistic mechanism of N and P species on the modification of Pt’s electronic structure and its subsequent impact on the electrocatalytic methanol oxidation behaviors on the Pt surface was thoroughly elucidated, providing a constructive route for designing robust MOR electrocatalysts with high MOR activity and durability.

Three-Dimensional MXene-Based Pd/Ni/Cu Electrocatalyst for Methanol Oxidation Reaction with Efficient Performance

Three-Dimensional MXene-Based Pd/Ni/Cu Electrocatalyst for Methanol Oxidation Reaction with Efficient Performance

Versailles Santa Barbara-5 derived bifunctional one-dimensional electrocatalysts of hierarchical Ni3S2 nanoprism@nanosheets arrays for self-supporting and binder-free efficient supercapacitor and methanol oxidation reaction

We herein present a structure consisting of two-dimensional (2D) single-crystal Ni3S2 nanosheets designed on one-dimensional (1D) Ni3S2 nanoprism arrays (also known as Ni3S2 nanoprism@nanosheets). These arrays are directly synthesized over nickel foam, which is referred to as Ni3S2/NF. These structures can be used as binderless, self-supporting electrodes for bifunctional methanol oxidation reaction (MOR) applications and high energy density hybrid supercapacitors (HSC). Ni3S2/NF is synthesized through the two steps of hydrothermal processes. In step I, 1D hexagonal Versailles Santa Barbara-5 (VSB-5) nanorod arrays have been prepared onto the surface of NF (denoted as VSB-5/NF). The precursor for step II was 1D VSB-5 nanorod arrays, which were transformed into Ni3S2 using Na2S as a sulfur source via the Kirkendall effect. Electrochemical examination results show that as-synthesized Ni3S2/NF electrode exhibited a high specific capacitance (Cs) of 145.0 mA h g−1 at 5 A g−1, low series resistance (0.18 Ω) and charge-transfer resistance (0.05 Ω), small relaxation time constant (τ0 = 8 ms) and high frequency response at 125.8 Hz. Ni3S2/NF has a superior specific capacity of 145.0 mA h g−1 at 5 A g−1 as a SC electrode. The Ni3S2/NF//CNTs/NF HSC can be operated up to 1.6 V in a 3 M KOH electrolyte, delivering an impressive energy density of 256.35 W h kg−1 at a power density of 6400 W kg−1. The as-assembled Ni3S2/NF//CNTs/NF HSC device exhibited an impressive stability of 81 % even after undergoing 10,000 charge-discharge cycles. When compared to previously reported catalysts, Ni3S2/NF was proved to be an excellent electrocatalyst for MOR due to its ability to generate a current density of 215.0 mA cm−2 at 0.5 VSCE, while maintaining a superior and stable current density of 619.2 mA cm−2 at 0.8 VSCE.

Triple-junction interfacial engineering Pt–CeO2/three-dimensional nitrogen-doped carbon frameworks electrocatalysts for methanol oxidation reaction

Efficient Pt-based catalysts towards anodic methanol oxidation reaction (MOR) is crucial to direct methanol fuel cells (DMFCs). Pt-based catalysts with triple-junction interfaces of Pt, metal oxidizes (MOx) and carbon materials have broad engineering prospect due to the synergistic effect among different composites. However, in Pt-MOx/carbon material catalysts reported previously, Pt and MOx nanoparticles (NPs) are too large and the triple-junction interfaces are insufficient. Herein, we innovatively introduce oxidized carbon nanotubes (OCNTs) into nitrogen-doped reduced graphene oxide (NrGO) sheets and propose a cost-efficient self-assembly process for the construction of three-dimensional nitrogen-doped carbon frameworks (NrGO-OCNTs). Furthermore, a modified solvothermal method is developed to uniformly deposit ultrafine Pt and CeO2 NPs onto NrGO-OCNTs so that sufficient Pt–CeO2–C triple-junction interfaces can be introduced. The obtained Pt–CeO2/NrGO7-OCNTs3 catalyst with the NrGO/OCNTs ratio of 7:3 shows the optimum electrochemical surface area and mass activity of 154.9 m2·gPt−1 and 845 A·gPt−1, respectively, which are 2.3 and 3.2 times higher than those of a commercial Pt/C catalyst. It also possesses excellent stability and anti-CO poisoning performance. These improvements may be attributed to the unique architecture of the support and enhanced synergistic effect among Pt, CeO2 and NrGO7-OCNTs3. This approach is simpler and more efficient than other methods reported previously and suitable for engineering of efficient Pt-based catalysts.

Competitive coordination-induced assembling of Ni-mof/NiFe-ldh heterostructure for enhanced electrocatalytic methanol oxidation

Direct methanol fuel cells (DMFCs) can permit the utilization of noble-metal-free electrocatalysts, which certainly reduces the cost and accelerates their practical implementation. With the exploration of efficient and economical methanol oxidation reaction (MOR) catalysts, Ni-based nanostructures have been recognized as the most promising MOR catalysts in alkaline media. Herein, we construct a novel heterojunction MOR electrocatalyst composed of Ni-based metal-organic framework (Ni-MOF) and NiFe-based layered double hydroxides (LDHs) through a coordination-induced self-assembly strategy. Owing to the synergic effect between Ni and Fe sites, coupled with the effect of hetero-interface, the resultant Ni-MOF/NiFe-LDH composite exhibits remarkable MOR activity in 0.1 M KOH electrolyte with the oxidation current density (32.66 mA cm−2) is 2.65 and 2.44 times higher than that of the primitive NiFe-LDH and Ni-MOF. The excellent stability of the Ni-MOF/NiFe-LDH electrocatalyst has also been confirmed by long-term chronoamperometry (CA) analysis. Our work paves a facile controllable way for fabricating MOF/LDH heterostructure targets on MOR and underlines its potential to boost energy conversion efficiency through the manipulation of synergic components.

Unveiling the Pivotal Role of dx2-y2 Electronic States in Nickel-Based Hydroxide Electrocatalysts for Methanol Oxidation.

The anodic methanol oxidation reaction (MOR) plays a crucial role in coupling with the cathodic hydrogen evolution reaction (HER) and enables the sustainable production of the high-valued formate. Nickel-based hydroxide (Ni(OH)2) as MOR electrocatalyst has attracted enormous attention. However, the key factor determining the intrinsic catalytic activity remains unknown, which significantly hinders the further development of Ni(OH)2 electrocatalyst. Here, we found that the electronic state within antibonding bands plays a decisive role in the whole MOR process. The onset potential depends on the deprotonation ability (Ni2+ to Ni3+), which was closely related to the band center of orbital. The closer of orbital to the Fermi level showed the stronger the deprotonation ability. Meanwhile, in the high potential region, the broadening of orbital would facilitate the electron transfer from methanol to catalysts (Ni3+ to Ni2+), further enhancing the catalytic properties. Our work for the first time clarifies the intrinsic relationship between electronic state and the MOR activities, which adds a new layer of understanding to the methanol electrooxidation research scene.

Unveiling the Pivotal Role of dx2−y2 Electronic States in Nickel‐Based Hydroxide Electrocatalysts for Methanol Oxidation

AbstractThe anodic methanol oxidation reaction (MOR) plays a crucial role in coupling with the cathodic hydrogen evolution reaction (HER) and enables the sustainable production of the high‐valued formate. Nickel‐based hydroxide (Ni(OH)2) as MOR electrocatalyst has attracted enormous attention. However, the key factor determining the intrinsic catalytic activity remains unknown, which significantly hinders the further development of Ni(OH)2 electrocatalyst. Here, we found that the electronic state within antibonding bands plays a decisive role in the whole MOR process. The onset potential depends on the deprotonation ability (Ni2+ to Ni3+), which was closely related to the band center of orbital. The closer of orbital to the Fermi level showed the stronger the deprotonation ability. Meanwhile, in the high potential region, the broadening of orbital would facilitate the electron transfer from methanol to catalysts (Ni3+ to Ni2+), further enhancing the catalytic properties. Our work for the first time clarifies the intrinsic relationship between electronic state and the MOR activities, which adds a new layer of understanding to the methanol electrooxidation research scene.

One-Step Synthesis of 3D Graphene Aerogel Supported Pt Nanoparticles as Highly Active Electrocatalysts for Methanol Oxidation Reaction.

Nowadays, two of the biggest obstacles restricting the further development of methanol fuel cells are excessive cost and insufficient catalytic activity of platinum-based catalysts. Herein, platinum nanoparticle supported graphene aerogel (Pt/3DGA) was successfully synthesized by a one-step hydrothermal self-assembly method. The loose three-dimensional structure of the aerogel is stabilized by a simple one-step method, which not only reduces cost compared to the freeze-drying technology, but also optimizes the loading method of nanoparticles. The prepared Pt/3DGA catalyst has a three-dimensional porous structure with a highly cross-linked, large specific surface area, even dispersion of Pt NPs and good electrical conductivity. It is worth noting that its catalytic activity is 438.4 mA/mg with long-term stability, which is consistent with the projected benefits of anodic catalytic systems in methanol fuel cells.. Our study provides an applicable method for synthesizing nano metal particles/graphene-based composites.

CeO2-supported Pt nanoclusters for improved electrochemical oxidation of methanol

Developing highly durable and active Pt-supported catalysts is currently the most prominent and practicable electrocatalyst design strategy for direct methanol fuel cells (DMFC) due to their high electrocatalytic stability and activity. Herein, we fabricated CeO2 nanorods with tiny Pt nanoparticles that possess good electrocatalytic behavior for methanol oxidation reaction (MOR). In addition, the presence of Ce3+ and small Pt nanoparticles (3.46 nm) enhanced strong metal interaction, facilitating the formation of oxygen vacancies on the CeO2 surface to boost the MOR performance. Hence, the Pt-CeO2 catalyst revealed high mass activity (1414.0 mA mg−1) and areal-specific activity (1.615 mA cm−2) towards MOR in an acidic electrolyte, which was three times that of the 20% Pt/C catalyst (545.4 mA mg−1 and 0.856 mA cm−2). Besides, the Pt-CeO2 catalyst exhibited excellent performance of MOR in an alkaline electrolyte and retained 90.44% of its initial mass activity after 5000 cycles due to the unique morphology and synergistic effects between Pt and CeO2. Pt-CeO2 is regarded as a promising MOR electrocatalyst for DMFC applications.Graphical

Nickel 2‐Methylimidazole Metal–Organic Framework Ultrathin Nanosheets/Titanium Carbide MXene Hybrid Nanostructure as a Bifunctional Electrocatalyst for Methanol and Urea Oxidation Reactions

In the development of direct methanol and direct urea fuel cells, efficient electrocatalytic methanol oxidation reaction (MOR) and urea oxidation reaction (UOR) are employed. These approaches are essential in fuel cell technology for addressing the rising global energy and environmental concerns. In this research, nickel 2‐methylimidazole metal–organic framework (Ni‐MOF) and Ni‐MOF‐integrated titanium carbide (Ti3C2) MXene hybrid nanostructures (Ni‐MOF/Ti3C2) were controllably synthesized via a facile solvothermal method. Ti3C2 MXene nanosheets are utilized as two‐dimensional support to enhance the catalytic activity of the Ni‐MOF/Ti3C2 hybrid nanostructure. Furthermore, the methanol and urea electro‐oxidation activity of the Ni‐MOF/Ti3C2 hybrid nanostructure is investigated. The synergistic effect between Ni‐MOF and Ti3C2 MXene resulted in excellent and durable electrochemical performance. Thus, the newly synthesized electrode material exhibited high electrocatalytic activity at 0.8 V vs. Hg/HgO for methanol (166 mA cm−2) and urea electro‐oxidations (161 mA cm−2). The methanol and urea oxidation rates of the Ni‐MOF/Ti3C2‐10 hybrid nanostructure are approximately five and three times higher than that of pure Ti3C2 MXene and pristine Ni‐MOF, respectively. This work provides the potential of the Ni‐MOF‐integrated Ti3C2 MXene hybrid nanostructure as a promising electrocatalyst for MOR and UOR.

Mixed-Dimensional Partial Dealloyed PtCuBi/C as High-Performance Electrocatalysts for Methanol Oxidation with Enhanced CO Tolerance.

Developing efficient electrocatalysts for methanol oxidation reaction (MOR) is crucial in advancing the commercialization of direct methanol fuel cells (DMFCs). Herein, carbon-supported 0D/2D PtCuBi/C (0D/2D PtCuBi/C) catalysts are fabricated through a solvothermal method, followed by a partial electrochemical dealloying process to form a novel mixed-dimensional electrochemically dealloyed PtCuBi/C (0D/2D D-PtCuBi/C) catalysts. Benefiting from distinctive mixed-dimensional structure and composition, the as-obtained 0D/2D D-PtCuBi/C catalysts possess abundant accessible active sites. The introduction of Cu as a water-activating element weakens the COads, and oxophilic metal Bi facilitates the OHads, thereby enhancing its tolerance to CO poisoning and promoting MOR activity. The X-ray photoelectron spectroscopy (XPS) and X-ray absorption fine structure spectroscopy (XAFS) collectively reveal the electron transfer from Cu and Bi to Pt, the electron-enrichment effect induced by dealloying, and the strong interactions among Pt-M (Cu, Pt, and Bi) multi-active sites, which improve the tuning of the electronic structure and enhancement of electron transfer ability. Impressively, the optimized 0D/2D D-PtCuBi/C catalysts exhibit the superior mass activity (MA) of 17.68 A mgPt -1 for MOR, which is 14.86 times higher than that of commercial Pt/C. This study offers a proposed strategy for Pt-based alloy catalysts, enabling their use as efficient anodic materials in fuel cell applications.

Multi-dimensional PtRu/Co3O4-Activated carbon Nano-Electrocatalyst: Metal–Support Interaction, and electronic contributions towards methanol electrooxidation in alkaline fuel cells

In this work, we report PtRu alloy system supported on Co3O4-activated carbon (Co3O4-C) prepared by direct reduction of H2PtCl6 and RuCl3 solutions as a highly active and durable electrocatalyst for methanol oxidation reaction. The electrochemical activity of the electrocatalysts was evaluated using electrochemical impedance spectroscopy (EIS), linear sweep voltammetry (LSV), cyclic voltammetry (CV), and chronoamperometry (CA). The formation of PtRu alloy on the Co3O4-C matrix, as well as their electronic interactions, is confirmed by employing X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and X-ray diffraction (XRD) techniques. The electrocatalysts showed distinct electrocatalytic activity in alkaline medium, depending on whether the catalysts contained PtRu alloy and whether they were supported on the hybrid Co3O4-C, proving their unique contributions to the electrocatalytic reaction. Benefiting from the strong metal-support interaction (SMSI) and electronic interaction between Pt and Ru, the PtRu/Co3O4-C displayed a highly efficient electrocatalytic performance with a mass activity of 6709 mAmgPt-1, a substantial improvement compared to the commercial Pt-based benchmark catalyst, which achieved only 212 mAmgPt-1. Furthermore, the PtRu/Co3O4-C showed excellent stability after 10 000 s, high durability after 500 cycles retaining 94 % of current density, and higher tolerance for CO. This enhanced catalytic performance can be attributed to the small nanoparticle sizes, high dispersion, large ECSA of 102.1 m2/g, and the synergy resulting from electronic coupling interactions.

Direct Electrocatalytic Methanol Oxidation on MoO3/Ni(OH)2: Exploiting Synergetic Effect of Adjacent Mo and Ni.

Ni-based materials have been widely investigated as methanol oxidation reaction (MOR) catalysts. The formation of NiOOH and its reduction to Ni(OH)2 are generally regarded as essential steps for methanol oxidation. However, in such an indirect route, the efficiency of proton coupled electron transfer is fundamentally limited by the rate of transition from Ni(OH)2 to NiOOH back and forth. Herein we demonstrate a direct MOR pathway on MoO3/Ni(OH)2 without the formation of a NiOOH mediator. The MoO3/Ni(OH)2 exhibits a benchmark electrocatalytic MOR current density of 1000 mA cm-2 at 1.52 V vs. RHE with a nearly 100% faradic efficiency, outperforming all the state of art MOR electrocatalysts. In-situ Raman spectroscopy confirms that NiOOH is not formed during the electrocatalytic MOR process on the MoO3/Ni(OH)2. Density functional theory calculations suggest that Ni2+ in MoO3/Ni(OH)2 serves as the methanol adsorption site while the doped Mo6+ plays a key role in capturing the deprotonated H·. Benefiting from the Mo-Ni synergistic effect, the energy barrier of the CH2O* → CHO* + H* process is significantly reduced, avoiding the NiOOH formation and leading to the direct MOR. Our research unravels a direct electrochemical MOR pathway that does not rely on NiOOH formation and provides a facile strategy of regulating the intermediate process barrier for MOR.

Assembly of two trinuclear-cluster-based metal-organic frameworks: Structures and methanol electro-oxidation properties

The direct methanol fuel cell (DMFC) is an efficient and non-polluting green energy conversion device. However, the electrocatalysts for the anodic methanol oxidation reaction (MOR) in DMFC are often precious metal catalysts, which suffer from high cost, poor stability, and easy deactivation. In this work, two isostructural metal-organic frameworks (MOFs) [M3(μ3-OH)(TATB)(Nic)2(H2O)2(DMA)] (M = Co, Ni) were successfully synthesized under solvothermal conditions. Both frameworks possess a unique trinuclear cluster [M3(μ3-OH)(COO)5] secondary building unit (SBU) and a rare binodal (3,7)-connected network. Due to the high density of metal sites and prominent pore system within CTGU-36-Ni, it can serve as an effective molecular electrocatalyst for MOR, while CTGU-36-Co is an inert material. Further experimental results showed that the introduction of conductive substances could lead to a significant increase in the MOR area activity of CTGU-36-Ni. This work not only provides a non-noble metal molecular MOR electrocatalyst but also opens a new vision for the design and application of crystalline materials in various energy conversion processes.