Electrochemical Oxidation Of Methanol Research Articles

Chrysanthemum‐Flowers‐Like Bimetal Oxide Based Electrocatalyst for Methanol Oxidation Reaction

Transition metal oxides have garnered attention for the methanol electro‐oxidation reaction owing to their easy availability, high catalytic applicability, and multiple oxidation capabilities. Bimetal‐based catalysts further enhance the performance of the methanol oxidation reaction. In this context, a chrysanthemum‐flower‐like MoO2/WO3 is synthesized through a solvothermal and annealing strategy. The morphology attests to the rough surface and pores in the catalyst, augmenting its surface area for reactions and enhancing catalytic applicability. Electrochemical oxidation of methanol yields an optimal current density of 0.99 mA cm−2 and 2.07 mA mg−1 at a potential of 0.57 V versus Ag/AgCl. The catalyst exhibits a remarkably low Tafel slope of 37.45 mV dec−1, affirming its rapid reaction kinetics. Electrochemical impedance spectroscopy (EIS) reveals an equivalent electronic circuit of R(Q(R(QR)Q(RW))), confirming low charge transfer resistance (Rct) and diffusion‐controlled kinetics attributable to the pores in the sample. The sample also demonstrates an electrochemically active surface area (ECSA) value equal to 0.122 mF cm−2 and long‐term stability over continuous 5000 s, exhibiting no change and high resistance to CO poisoning. All these characterizations and obtained results collectively affirm that the chrysanthemum‐flower‐like MoO2/WO3 serves as a highly suitable electrocatalyst for the electrochemical oxidation of methanol.

Nickel-Iron-Modified 2D Metal-Organic Framework as a Tunable Precatalyst for Electrochemical Water Oxidation.

Mixed-metal metal-organic framework (MOF)-based water oxidation precatalysts have aroused a great deal of attention due to their remarkable catalytic performance. Yet, despite significant advancement in this field, there is still a need to design new MOF platforms that allow simple and systematic control over the final catalyst's metal composition. Here, we show that a Zr-BTB 2D-MOF could be used to construct a series of Ni-Fe-based oxide hydroxide water oxidation precatalysts with diverse Ni-Fe compositions. In situ Raman spectroscopy characterization revealed that the MOF precatalysts could be electrochemically converted to the active catalysts (NiFeOOH). In turn, it was found that the highest water oxidation activity was obtained with a catalyst containing a 47:53 Ni:Fe molar ratio. Additionally, the obtained catalyst is also active toward electrochemical methanol oxidation, exhibiting high selectivity toward the formation of formic acid. Hence, these results could pave the way for the development of efficient electrocatalytic materials for a variety of oxidative reactions.

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

Ultrathin NiV Layered Double Hydroxide for Methanol Electrooxidation: Understanding the Proton Detachment Kinetics and Methanol Dehydrogenation Oxidation.

Electrochemical methanol oxidation reaction (MOR) is regarded as a promising pathway to obtain value-added chemicals and drive cathodic H2 production, while the rational design of catalyst and in-depth understanding of the structure-activity relationship remains challenging. Herein, the ultrathin NiV-LDH (u-NiV-LDH) with abundant defects is successfully synthesized, and the defect-enriched structure is finely determined by X-ray adsorption fine structure etc. When applied for MOR, the as-prepared u-NiV-LDH presents a low potential of 1.41V versus RHE at 100mA cm-2, which is much lower than that of bulk NiV-LDH (1.75V vs RHE) at the same current density. The yield of H2 and formate is 98.2% and 88.1% as its initial over five cycles and the ultrathin structure of u-NiV-LDH can be well maintained. Various operando experiments and theoretical calculations prove that the few-layer stacking structure makes u-NiV-LDH free from the interlayer hydrogen diffusion process and the hydrogen can be directly detached from LDH laminate. Moreover, the abundant surface defects upshift the d-band center of u-NiV-LDH and endow a higher local methanol concentration, resulting in an accelerated dehydrogenation kinetics on u-NiV-LDH. The synergy of the proton detachment from the laminate and the methanol dehydrogenation oxidation contributes to the excellent MOR performance of u-NiV-LDH.

Phosphorous, boron and sulphur-doped silver tungstate-based nanomaterials toward electrochemical methanol oxidation and water splitting energy applications

We employed a one-step precipitation approach to produce B, P, and S-doped Ag2WO4 (AgW) with the aid of a cetyltrimethylammonium bromide template in order to develop novel catalytic materials with components and architectures that tolerate harsh conditions. The P@AgW with the spherical (13.7 nm) shape was found to possess the greatest electrocatalytic activity for the oxidation of methanol in an acidic environment. It provides remarkable performance with an overpotential of 0.58 V (at a current density of 10 mA cm−2 comprised of mass activity of 1172 mA g−1) and considerable long-term reliability. This is attributed to the intense increase in the β-Ag2WO4/α-Ag2WO4 ratio (4:1), the formation of Ag–O–P, the highest electrochemical surface area, and the ease of charge transfer. The B@AgW electrode of polymorphic structure, on the other hand, performed the best for water electrolysis in the basic medium (1.0 M KOH). It produces an OER at overpotentials of 50 mA cm−2 at 0.42 V and 399 mV at 10 mA cm−2. At 10 mA cm−2, the HER overpotential was 0.33 V. Additionally, the B@AgW electrolyzer shows a cell voltage of 1.44 V for overall water splitting, which is lower than that of P@AgW (1.56 V), and it demonstrates great durability for 20 h. The notably higher activity of B@AgW compared to other electrolyzers is due to improved electrical conductivity, transport of mass, more active sites, and reduced particle size (7.2 nm). This work offers a simple way for the large-scale manufacture of electrocatalysts with considerable activity and reliability over time.

Resolving Atomic-Scale Structure and Chemical Coordination in High-Entropy Alloy Electrocatalysts for Structure-Function Relationship Elucidation.

The recent breakthrough in confining five or more atomic species in nanocatalysts, referred to as high-entropy alloy nanocatalysts (HEAs), has revealed the possibilities of multielemental interactions that can surpass the limitations of binary and ternary electrocatalysts. The wide range of potential surface configurations in HEAs, however, presents a significant challenge in resolving active structural motifs, preventing the establishment of structure-function relationships for rational catalyst design and optimization. We present a methodology for creating sub-5 nm HEAs using an aqueous-based peptide-directed route. Using a combination of pair distribution function and X-ray absorption spectroscopy, HEA structure models are constructed from reverse Monte Carlo modeling of experimental data sets and showcase a clear peptide-induced influence on atomic-structure and chemical miscibility. Coordination analysis of our structure models facilitated the construction of structure-function correlations applied to electrochemical methanol oxidation reactions, revealing the complex interplay between multiple metals that leads to improved catalytic properties. Our results showcase a viable strategy for elucidating structure-function relationships in HEAs, prospectively providing a pathway for future materials design.

Boosting the Hydrogen Production Coupling with Electrochemical Methanol Oxidation to Formate Using Monolayered Layered Double Hydroxide Nanosheets

Boosting the Hydrogen Production Coupling with Electrochemical Methanol Oxidation to Formate Using Monolayered Layered Double Hydroxide Nanosheets

Precision tuning of highly efficient Pt-based ternary alloys on nitrogen-doped multi-wall carbon nanotubes for methanol oxidation reaction

The electrochemical methanol oxidation is a crucial reaction in the conversion of renewable energy. To enable the widespread adoption of direct methanol fuel cells (DMFCs), it is essential to create and engineer catalysts that are both highly effective and robust for conducting the methanol oxidation reaction (MOR). In this work, trimetallic PtCoRu electrocatalysts on nitrogen-doped carbon and multi-wall carbon nanotubes (PtCoRu@NC/MWCNTs) were prepared through a two-pot synthetic strategy. The acceleration of CO oxidation to CO2 and the blocking of CO reduction on adjacent Pt active sites were attributed to the crucial role played by cobalt atoms in the as-prepared electrocatalysts. The precise control of Co atoms loading was achieved through precursor stoichiometry. Various physicochemical techniques were employed to analyze the morphology, element composition, and electronic state of the catalyst. Electrochemical investigations and theoretical calculations confirmed that the Pt1Co3Ru1@NC/MWCNTs exhibit excellent electrocatalytic performance and durability for the process of MOR. The enhanced MOR activity can be attributed to the synergistic effect between the multiple elements resulting from precisely controlled Co loading content on surface of the electrocatalyst, which facilitates efficient charge transfer. This interaction between the multiple components also modifies the electronic structures of active sites, thereby promoting the conversion of intermediates and accelerating the MOR process. Thus, achieving precise control over Co loading in PtCoRu@NC/MWCNTs would enable the development of high-performance catalysts for DMFCs.

Synthesis of Ni3 B/Ni via Vacuum-Induced for Ultrahigh Stable and Efficient Methanol Oxidation.

Designing efficient catalysts to promote the electrochemical oxidation of anodes is the core of the development of electrochemical synthesis technologies, such as HER and CO2 RR. Here, a novel vacuum induction strategy is used to synthesize nickel boride/nickel (Ni3 B/Ni) heterostructure catalyst for electrochemical oxidation of methanol into formic acid. The catalyst has extremely high reactivity (only 146.9mV overpotential at 10mAcm-2 , the maximum current density reaches 555.70mAmg-1 and 443.87mAcm-2 ), ultra-high selectivity (Faraday efficiency of methanol conversion to formic acid is close to 100%), and ultra-long life (over 50h at 100mAcm-2 ). In-suit electrochemical impedance spectroscopy proved that MeOH is oxidized first and inhibits the phase transition of the electrocatalyst to the high-valent electrooxidation products, which not only enables the high selectivity of MeOH oxidation but also ensures high stability of the catalyst. The mechanism studies by density functional theory calculations show that the potential determining step, the formation of *CH2 O, occurs most favorably in the Ni3 B/Ni heterostructure. These results provide references for the development of MeOH oxidation catalysts with high activity, high stability, high selectivity, and low cost.

Efficient electro catalytic performance of palladium nanoparticles assisted on bi-composite material (GRNPs-GCN) for electro chemical oxidation of methanol in alkaline media

This study reports a novel co-deposited catalyst which covalently coupled composite of Pd@ GRNPs-GCN for methanol electro-oxidation was investigated. The prepared nanocomposite material was further characterized through FTIR, XRD, SEM, and EDX analysis. The results showed that the Pd@GRNPs-GCN has stronger interaction, active specific area & rich content of pyridine & pyrrole nitrogen species which promotes the dispersion of PdNPs on GRNPs-GCN to present superior catalytic efficiency towards MOR. Moreover, the electrochemical analysis of cyclic voltammetry (CV), chronoamperometry (CA) & electro chemical impedance spectroscopy (EIS) proved that fabricated Pd@GRNPs-GCN electro catalyst showed significant catalytic activity, lesser oxidation potential & longevity for the electrochemical oxidation of methanol in alkali media. All these results revealed that the nanocomposite hybrid electro catalyst for feature endeavours in DMFCs (Direct methanol fuel cells) applications.

Ni(OH)2-SnO2 at the Hybrid Interface of Zeolite-Y and rGO for Electrochemical Oxidation of Methanol and Ethanol

Ni(OH)₂-SnO₂ at the Hybrid Interface of Zeolite-Y and rGO for Electrochemical Oxidation of Methanol and Ethanol

Atomically embedded synergetic dual-metal catalysis FeO&MoS2 nanoparticles on sodalite structural zeolite toward electrochemical methanol oxidation reaction

To improve the performance of the direct methanol fuel cells (DMFCs), the atomically embedded synergetic dual-metal catalyst nanosized ferrous oxide & molybdenum disulfide @ sodalite structural zeolite (FeO&MoS2@SOD) is designed and generated through self-assemble process under hydrothermal condition. The FeO&MoS2@SOD is characterized by SEM, XRD, TEM, EDX and XPS to reveal its morphology, composition, fine structure, element distribution and element valence, respectively. Its performance in the electrochemical methanol oxidation reaction (MOR) is investigated by EIS, CV and A i-t C with the current density of 24.33 mA cm−2 or 144 mA mg−1, and the power density of 33.99 mW cm−2. The excellent behavior of the obtained catalyst could be ascribed to the synergic effect of the highly dispersed FeO and MoS2 nanoparticles on the surface of the zeolite.

Paired Electrosynthesis of Formic Acid from CO2 and Formaldehyde from Methanol

Electrochemical carbon dioxide (CO2) reduction provides a pathway to sustainable chemicals. However, the high electrical energy demand is still a major challenge. Cathodic (CO2) reduction is typically paired with the anodic oxygen evolution reaction (OER), which is energy intensive with limited added value. In this experimental work, we replace OER with partial methanol oxidation to reduce the energy demand while producing formaldehyde and formic acid as value-added chemicals. We investigate methanol oxidation on metallic and oxidized platinum and the paired process with CO2 reduction to formic acid in an electrochemical flow cell. Methanol oxidation on oxidized platinum was more selective to formaldehyde than on metallic platinum but required a higher potential. In the paired process, we achieved a current efficiency for formaldehyde of up to 58% on oxidized platinum at 75 mA cm–2 and 1.8 V vs RHE reaching a concentration of 1.14 mol L–1 formaldehyde. The current efficiency for formaldehyde and formic acid combined reached up to 89%. Methanol oxidation was not affected by pairing, while the current efficiency of CO2 reduction decreased. We report the first production of formaldehyde beyond mechanistic studies by electrochemical methanol oxidation and demonstrate paired CO2 reduction with formaldehyde as primary anodic product.

Understanding Trends in Electrochemical Methanol Oxidation Reaction Activity on a Single Transition-Metal Atom Embedded in N-Coordinated Graphene Catalysts

The lack of efficient catalysts and research on the mechanism for the methanol oxidation reaction (MOR) impedes the development of direct methanol fuel cells. In this work, based on density functional theory calculations, we systematically investigated the activity trends of electrochemical MOR on a single transition-metal atom embedded in N-coordinated graphene (M@N4C). By calculating the free energy diagrams of MOR on M@N4C, Co@N4C was screened out to be the most effective MOR catalyst with a low limiting potential of 0.41 V due to the unique charge transfers and electronic structures. Importantly, one- and two-dimensional volcano relationships in MOR on M@N4C catalysts are established based on the d-band center and the Gibbs free energy of and ΔG*CO, respectively. In one word, this work provides theoretical guides toward the improved activity of MOR on M@N4C and hints for the design of active and efficient MOR electrocatalysts.

Boosting DMFC power output by adding sulfuric acid as a supporting electrolyte: Effect on cell performance equipped with platinum and platinum group metal-free cathodes

Direct methanol fuel cells (DMFCs) are promising electrochemical systems capable of producing electricity from the electrochemical oxidation of methanol and the reduction of oxygen. In this work, the effectiveness of the addition of sulfuric acid as a supporting electrolyte for methanol fuel composition was assessed. The results showed that the peak of power curve in DMFCs with Pt/C cathode electrocatalysts increased progressively from 70 mW cm−2 (0 mM of H2SO4) to 115 mW cm−2 with a concentration of 100 mM of H2SO4. These results underlined the positive effect of the addition of a supporting electrolyte in the methanol aqueous solution on the electrochemical output that was enhanced. Platinum group metal-free (PGM-free) electrocatalysts based on Fe-Nx-C type were also tested being insensitive to methanol crossover and oxidation at the cathode. DMFC with Fe–N–C cathode catalysts result in a performance of 21.5 mW cm−2. In these operating conditions, the addition of supporting electrolyte does not seem to bring excessive advantage. Short stability tests are presented and an overall assessment of the resistances within the system is also discussed.

Green preparation of self-supporting platinum nanoflower catalyst and its electrocatalytic oxidation performance of methanol

The three-dimensional (3D) self-supporting Pt nanoflower catalyst was prepared by using Pt organic compounds as precursors in a low-temperature molten salt system. The obtained Pt nanoflower nanoparticle can reach 400–500 nm with a face-centered cubic structure, which has the structural characteristics of a loose framework and more exposed active sites. The surfactant-free Pt nanoflower was directly used as methanol electrooxidation reaction (MOR) electrocatalysts without any pretreatment and activated carbon support. The results of electrochemical catalytic oxidation of methanol showed that the Pt nanoflower catalyst exhibit more enhanced electrocatalytic oxidation performance toward methanol compared with the commercial platinum black catalyst. The green and effective method can be developed and expected to enable mass production of fuel cell catalysts.

Toward abiotic sugar synthesis from CO2 electrolysis

Toward abiotic sugar synthesis from CO2 electrolysis

Efficient synthesis of PdIr nanocatalysts with controllable surface composition for electrochemical oxidation of methanol

Pure iridium (Ir) is easy to produce OH adsorbent species and has a wide range of applications in electrocatalysis. The structure–activity relationship between controlled synthesis and surface regulation of Ir-based alloys and their properties needs further study.When P123(poly (ethylene oxide)-poly (ethylene oxide)-poly (ethylene oxide)(PEO20-PPO70-PEO20) is used as reducing agent and protective agent, the ir-rich core–shell structure PdIr@Ir catalyst can be obtained by the solution thermal method without adding KI, and the PdIr alloy can be obtained after the addition of KI. The complexation ability of KI can change the reduction rate of the precursor and regulate the surface composition of the catalyst.After optimizing the dose of KI, the PdIr-4 shows the highest methanol oxidation reaction (MOR) activity and anti-CO toxicity.The PdIr-2 catalysts with rich Ir on the surface showed high stability, possibly due to the gradual activation of Ir on the surface by PdIr inside. The results of experimental characterization and theoretical calculations show that the main reasons for the performance improvement of PdIr series catalysts are the special three-dimensional structure of PdIr, the bifunctional mechanism between Pd and Ir, especially the synergistic catalytic action of Ir and the effect of regulating the electron structure.The experimental results of this paper are expected to provide some ideas and guidance for Ir-based catalysts with high activity and high stability.

Tubular Nickel Hydroxide Embedded in Zeolitic Cobalt Oxide for Methanol Oxidation Reaction

Non-noble metal-based electrocatalysts have been designed for effective electrochemical oxidation of methanol in basic medium. The catalyst consisting of nickel (Ni) and cobalt (Co) metals was synthesized with a zeolitic imidazolate framework (ZIF) template approach. Such a method leads to the decoration of cylindrically shaped nickel hydroxides, Ni(OH)2, in nanodimensions within the zeolitic crystals of spinel cobalt oxides, Co3O4. The mixed metal hydroxide and oxide, Ni(OH)2-Co3O4, represented good activity toward electrochemical oxidation of methanol in 1 M KOH at a low onset potential. When combined with a carboxylate-functionalized multiwalled carbon nanotube (COOH-MWCNT), the same material, Ni(OH)2-Co3O4, exhibited superior MOR (methanol oxidation reaction) activity, giving a peak current density of 4.2 Amg–1 at similar conditions. The MWCNT-modified catalyst, Ni(OH)2-Co3O4-MWCNT, also showed high stability up to 500 cycles and 25000 s without a significant loss in the current density. The linear dependency of the current density against the square root of the scan rate indicated a diffusion-controlled MOR process. The decrease in onset potential with increasing scan rate also predicted a kinetically favorable MOR process. Fourier transform infrared and Raman analyses suggested that the MOR mechanism proceeded through the adsorption of methanol (CH3OH) on the catalyst surface, and its deprotonation formed the methoxide ion (CH3O–) which in the later course decomposed to CO2 and H2O. The Raman study also showed that, during the electrochemical oxidation process, Co2+ species in Co3O4 transformed to CoOOH and thereby favored the MOR.

Modulating hydrogen bonding in single-atom catalysts to break scaling relation for oxygen evolution

The universal scaling relation between reaction intermediates with correlated adsorption has restricted energy-conversion efficiency in some catalytic processes such as oxygen evolution reaction (OER) for hydrogen production. Overcoming this intrinsic barrier requires differentiated adsorption of oxygenated intermediates. In this work, we introduce single-atom Ir species on CoOOH and Co0.8Cu0.2OOH, where their hydrogen bonding interactions with ∗OH and ∗OOH intermediates were tuned by localized structures. Electrochemical methanol oxidation measurements and in situ attenuated total reflection Fourier transform infrared (ATR-FTIR) spectra revealed different adsorptions of ∗OH and ∗OOH intermediates over Ir1/CoOOH and Ir1/Co0.8Cu0.2OOH. Theoretical calculations further showed that the presence of cationic vacancies in Ir1/Co0.8Cu0.2OOH elongates the interaction distance between atomic iridium species and one of the key intermediates, ∗OH, leading to distinct adsorptions of ∗OH and ∗OOH. Consequently, Ir1/Co0.8Cu0.2OOH overcome the theoretical minimum energy barrier of 370 mV toward OER under scaling relation, presenting a lower theoretical overpotential barrier of 310 mV.