Onset Potential For Oxidation Research Articles

Influence of different morphologies on the catalytic activity of Pt-Pd nanostructures for methanol oxidation

Developing efficient and durable catalysts for methanol oxidation in acidic media remains a significant challenge in electrochemical energy conversion. This study addresses this issue by synthesizing Pt-Pd bimetallic electrocatalysts with different morphologies, including nanowires, core-shell nanoparticles, and core-shell nanowires, and evaluating their catalytic activities. The electrocatalysts were prepared via chemical reduction of metal precursors using formic acid as a reducing agent. X-ray diffraction analysis revealed distortions in the lattice parameters of the nanostructured bimetallic catalysts, and STEM/EDX analysis confirmed the formation of the different morphologies on the carbon support. Electrochemical assessments showed that the bimetallic catalysts exhibited superior catalytic activities to nanostructured Pt/C catalysts. The Pd@Pt/C core-shell nanowires displayed the highest catalytic efficiency, with the lowest methanol oxidation onset potential (468 mV) and the highest mass and specific activities. Electrochemical impedance measurements revealed the lowest charge transfer resistance value for the Pd@Pt/C core-shell nanowires. Chronoamperometric tests further indicated that the Pd@Pt/C core-shell nanowires catalyst exhibited superior tolerance to inactivation by reaction intermediates, achieving mass and specific activities approximately twice as high as those of the Pt/C catalyst. The enhanced catalytic performance of the Pd@Pt/C core-shell nanowires was attributed to the synergistic effects of the two morphologies that alter the electronic and geometric structures of the Pt within the catalyst.

N-doped titanium oxide/carbon composite as supports for platinum catalysts in highly efficient methanol oxidation

The commercialization of direct methanol fuel cells (DMFCs) faces significant challenges due to the susceptibility of conventional platinum-based catalysts to poisoning by intermediates such as CO and HCOO− generated during the methanol oxidation reaction (MOR). This study details the synthesis of a highly porous titanium dioxide/carbon composite (TCC) using NH2-MIL-125(Ti) (MIL = Matérial Institut Lavoisier) as a precursor. To enhance the conductivity and catalytic properties of TCC, a nitriding reaction is conducted in an NH3 atmosphere, producing a nitrogen-doped titanium oxide/carbon composite (N-TCC). The resulting N-TCC is employed as a support for a platinum catalyst to improve MOR performance in DMFCs. The Pt/N-TCC catalyst demonstrates high catalytic performance, achieving a mass activity of 537 mA mg−1 for the MOR, marking a 39 % increase over the commercial Pt/C catalyst. Furthermore, the Pt/N-TCC catalyst exhibits a low onset potential for CO oxidation, a higher If/Ib ratio, and greater stability in chronoamperometry test, indicating high resistance to CO poisoning and enhanced chemical stability. Therefore, N-TCC can be used as a promising support for Pt-based catalysts in DMFC applications.

A General Hydrotrifluoromethylation of Unactivated Olefins Enabled by Voltage-Gated Electrosynthesis.

Here we present the first successful hydrotrifluoromethylation of unactivated olefins under electrochemical conditions. Commercially available trifluoromethyl thianthrenium salt (TT+-CF3BF4-, Ep/2 = -0.85 V vs Fc/Fc+) undergoes electrochemical reduction to generate CF3 radicals which add to olefins with exclusive chemoselectivity. The resulting carbon centered radical undergoes a second cathodic reduction, instead of a classical HAT process, to generate a carbanion that can be terminated by protonation from solvent. The use of MgBr2 (+0.20 V onset oxidation potential) plays a key role as an enabling sacrificial reductant for the reaction to operate in an undivided cell. Guided by cyclic voltammetry (CV) studies, fine-tuning the solvent system, trifluoromethylating reagent's counteranion and careful selection of redox processes, this work led to the development of a voltage-gated electrosynthesis by pairing two redox processes with a narrow potential difference (ΔE ≈ 1.00 V) allowing the reaction to proceed with two important advances: (a) high reactivity and selectivity towards hydrotrifluoromethylation over undesired dibromination, and (b) an unprecedented functional group tolerance, including aniline, phenols, unprotected alcohol, epoxide, trialkyl amine, and several redox sensitive heterocycles.

On the mechanism and energetics of electrochemical alloy formation between mercury and platinum for mercury removal from aqueous solutions

Mercury pollution is an acute global concern threatening the health of humans and wildlife. Thus, there is a need for new and improved techniques to reduce emissions and remove toxic mercury from aqueous environments. Electrochemical alloy formation, specifically between mercury ions in aqueous solution and a platinum electrode, emerges as a promising solution. Through analysis of reaction mechanisms and energetics related to the formation and dissolution of the PtHg4 alloy, this study aims to deepen our understanding of the underlying processes of effective electrochemical mercury removal. Potentiodynamic measurements indicate rapid alloy formation at a clean platinum surface, proceeding with only trace amounts of metallic mercury on the surface. However, once the electrode surface has sufficient mercury coverage with an alloy thickness of around 1.5 nm, clear evidence of metallic mercury on the surface is observed. Furthermore, the amount of absorbed mercury on the cathode increases linearly in time. The onset potential for the alloy formation is experimentally determined using electrochemical quartz crystal microbalance with dissipation monitoring to be approximately 0.64 V vs. SHE, and the alloy dissolution (oxidation) onset potential is found to be approximately 0.98 V vs. SHE, at a mercury ion concentration of 10 mg/L. Density functional theory calculations are used to provide a theoretical value for the reversible potential from a thermodynamics perspective, yielding a value of 0.78 V vs. SHE at a mercury ion concentration of 10 mg/L. This value is in excellent agreement with the experimental results, suggesting an overpotential of about 0.14 and 0.20 V for the alloy formation and oxidation, respectively. These findings provide important information on the reaction mechanisms and overpotentials of the PtHg4 alloy formation and dissolution, which are key factors for development of large-scale mercury removal based on this technique, as well as fundamental understanding of the electrochemical alloy formation between mercury ions and platinum.

Two-Dimensional Nanorod-Shaped Co(II) Coordination Polymer on Three-Dimensional Metallic Foam: A Hybrid Platform for Electrochemical Oxidation of Glucose.

This study unveils a novel electrochemical biosensor for monitoring glucose in biological fluids by employing nanorods of a cobalt-bispyridyl/dicarboxylate framework grown in a layer-by-layer manner on a highly porous nickel substrate. The hybrid microporous system has a bicatalytic effect on glucose oxidation due to the synergistic catalytic impact of the nickel and cobalt ions with varying oxidation states as electroactive sites. In addition, the controlled growth of inorganic-organic frameworks changes the mechanism of electron transfer from a diffusion-controlled process to an adsorption-controlled process, thus yielding a low onset oxidation potential (∼0.21 V/Ag-AgCl) and a high current intensity (∼1 mA) for the oxidation of glucose in alkaline media. A fast response time (∼2 s) and a reasonably high sensitivity (0.14 μA μM-1) within a broad linear range (40-360 μM) have determined the suitability and superiority of the hybrid electrode for glucose monitoring compared to many metal-organic-based biosensors. The facile fabrication process of the Co(II) coordination polymer/Ni substrate with a large surface area that benefits from the synergetic catalytic activity of nickel-cobalt hybrids may pave the way for the development of novel hybrid electrodes for biosensors and direct glucose fuel cells.

Bidirectional Voltage Regulation for Integrated Photovoltachromic Device Based on P3HT-Electrochromic Unit and Perovskite/Organic Tandem Solar Cells.

Integrated electrochromic devices powered by photovoltaic cells have evoked a lot of interest due to their promising commercial prospects. However, their application has been restricted by the voltage adaption between the self-powered voltage and the color-changing threshold voltage (Vt). Herein, a strategy of bidirectional voltage regulating is proposed to develop a novel stand-alone integrated photovoltachromic device (I-PVCD), which integrates perovskite/organic tandem solar cells (P/O-TSCs) to drive color-changing process of conjugated poly(3-hexylthiophene) (P3HT) films. To lower the driving-voltage of electrochromic layer, C60 is introduced to decrease the onset oxidation potential of P3HT film, and thus leading to a reduced Vt of 0.70V benefiting from the enhanced highest occupied molecular orbital level and decreased charge transfer resistance from 67.46 to 49.89 Ω. Simultaneously, PBDB-T is utilized as the hole transport layer in the interconnecting layer of CsPbI2Br/PTB7-Th:IEICO-4F P/O-TSC to improve its open-circuit voltage (Voc) to 1.85V. Under their synergetic merits, a I-PVCD with a wider self-adaptive voltage range is achieved. This device can undergo fast and reversible chromic transition from beautiful magenta to transparent only under the solar radiation, and demonstrates a coloration efficiency of 351.90 cm2 C-1 and a switching time of 2 s besides its excellent operating reliability.

Tunable optoelectronic performances of novel 7H-benzo[c]fluoren-7-one acceptor unit-based conjugated D-A polymers

In this paper, two novel D-A-D type molecules (EBZFO1 and TBZFO2), which consisting of 7 H-benzo[c]fluoren-7-one as electron acceptor (A) unit, 3,4-ethylenedioxythiophene (EDOT) and thiophene (Th) as the terminal donor (D) units, were designed and synthesized. Afterwards, the corresponding D-A polymers of P(EBZFO1) and P(TBZFO2) were prepared by electrochemical deposition method. The electrochemical behavior of the monomers, electrochemical, and electrochromic properties of the D-A polymers were comparatively studied. Although both of the monomers have lower onset oxidation potentials (1.0 V/1.2 V) and good adherence on the electrode, the redox stability of their polymers was very different. P(EBZFO1) displayed much better redox stability (remaining 78.4 % electroactivity after 1000 cycles), good optical stability (2 % reduction in optical contrast after 1500 s), and stable optical memory, while P(TBZFO2) remained inferior redox stability with only 8.82 % of its original electroactivity was retained after 1000 cycles. As a result, higher optical band gap of P(TBZFO2) (1.65 eV) displayed much worse electrochromic performances with the normal optical contrast (11.4 %∼46 %) and relatively slow switching time (2.5–3.8 s). By contrast, P(EBZFO1) (band gap: 1.55 eV) showed favorable optical contrast (15.8 %) at 1100 nm with a very fast response time of 0.24 s, and decent coloration efficiency (228.8 cm2 C−1 at 433 nm). From these results, P(EBZFO1) can further render an appropriate electrochromic material for the smart windows or displays.

In Situ Construction of a Polymer Coating Layer on the LiNi0.8Co0.1Mn0.1O2 Cathode for High-Performance Lithium-Ion Batteries.

Lithium-ion batteries (LIBs) are known for their high energy density but exhibit poor cyclic stability and safety risks due to side reactions between the electrode and electrolyte. To address these issues, a novel approach involving construction of a polymer coating layer (PCL) via in situ self-polymerization using 2,2,3,4,4,4-hexafluorobutyl methacrylate (HFBM) as an electrolyte additive on the cathode is proposed. The PCL endows the electrolyte with a high onset oxidation potential (4.78 V) and lithium-ion transference number (0.52). The uniform and robust in situ constructed PCL can effectively inhibit the severe irreversible side reactions and suppress harmful reactions, thus providing a protective barrier against degradation. The resulting Li||LiNi0.8Co0.1Mn0.1O2 batteries exhibit an improved discharge capacity retention of 80% at 1C over 100 cycles. These results demonstrate that the in situ self-polymerization strategy holds promising potential for enhancing LIB performance and long-term stability, especially when high-voltage cathode materials are used.

Molybdenum–Based Electrocatalysts for Direct Alcohol Fuel Cells: A Critical Review

<p>Direct alcohol fuel cells (DAFCs) have gained much attention as promising energy conversion devices due to their ability to utilize alcohol as a fuel source. In this regard, Molybdenum-based electrocatalysts (Mo-ECs) have emerged as a substitution for expensive Pt and Ru–based co-catalyst electrode materials in DAFCs, owing to their unique electrochemical properties useful for alcohol oxidation. The catalytic activity of Mo-ECs displays an increase in alcohol oxidation current density by several folds to 1000–2000 mA mg<sub>Pt</sub><sup>−1</sup>, compared to commercial Pt and PtRu catalysts of 10–100 mA mg<sub>Pt</sub><sup>−1</sup>. In addition, the methanol oxidation peak and onset potential have been significantly reduced by 100–200 mV and 0.5–0.6 V, respectively. The performance of Mo-ECs in both acidic and alkaline media has shown the potential to significantly reduce the Pt loading. This review aims to provide a comprehensive overview of the bifunctional mechanism involved in the oxidation of alcohols and factors affecting the electrocatalytic oxidation of alcohol, such as synthesis method, structural properties, and catalytic support materials. Furthermore, the challenges and prospects of Mo-ECs for DAFCs anode materials are discussed. This in-depth review serves as valuable insight toward enhancing the performance and efficiency of DAFC by employing Mo-ECs.</p>

Advanced low-dimensional PdAg networked nanochains for the superior alcohol electrocatalysis

Advanced 1D materials have become the focus due to the enhanced structure durability than 0D nanoparticles (NPs). Unfortunately, the unique electrocatalysts with 0D-1D composite structure are rarely reported. Herein, the low-dimensional PdAg networked nanochains (NNCs) with diverse element composition assembled from a sequence of NPs were designed as efficient 0D-1D electrocatalysts toward the ethylene glycol oxidation reaction (EGOR) and ethanol oxidation reaction (EOR). The low-dimensional PdAg NNCs not only possess stronger structure stability than 0D NPs, but also endow catalysts with more abundant active sites than traditional 1D nanochains. Attributed to the synergistic electronic effect, abundant active sites and surface defects, the composition-optimized PdAg-2 NNCs behaved the optimal electrocatalytic activities, greatly surpassing most of reported studies. Benefiting from 0D-1D composite structure and stable networked nanochain feature, the PdAg-2 NNCs still remained higher current density after the 3600 s chronoamperometry (CA) experiment and without obvious decline through three consecutive CA tests compared to commercial Pd/C, revealing the remarkable stability. Meanwhile, the PdAg-2 NNCs exhibited the prominent anti-CO poisoning ability and the lowest onset oxidation potential, manifesting the enhanced reaction kinetics. This work fabricated a novel electrocatalyst with low-dimension composite structure, producing new guidelines for the synthesis of high-efficiency electrocatalysts.

Preparation of MOF-derived molybdenum-carbide-modified PtCu nano-alloy catalysts and their methanol oxidation performance

The catalytic performance of Pt0.10/Cu-MoC catalyst is higher than that of commercial Pt/C. After stability test, the performance has reserved to 79.2% of the initial value, and the onset potential for CO oxidation is lower than that of commercial Pt/C.

Extending the Success of Halide Perovskites from Solar Cells to Photoelectrodes and Photocatalysts

Photoelectrochemical and photocatalytic conversion of water and carbon dioxide using solar energy offers a clean and sustainable solution to meet the world’s energy requirements. Achieving their full potential depends on developing inexpensive photoelectrodes and photocatalysts that can efficiently absorb solar light and drive photoinduced charges to react with water and carbon dioxide. In this talk, I will present the recent developments of our group in the preparation of inexpensive photoanodes and photocatalysts made of halide perovskites such as CsPbBr3. These materials are revolutionizing the photovoltaics field due to their high absorption coefficient and excellent optoelectronic properties, and now offer an opportunity to revolutionize photoelectrochemistry and photocatalysis if their instability in aqueous environments is addressed. We have found novel strategies to protect halide perovskites with printed carbon layers and graphite sheets functionalized with NiFeOOH water-oxidation electrocatalyst, achieving photoanodes with low onset potential (+0.4 VRHE) for solar water oxidation. We have also managed to boost charge separation in these photoanodes by engineering the CsPbBr3 phase to a 3D one that achieves enhanced energetics and better band alignment to the TiO2 electron transport layer and printed carbon electrode layer, achieving photocurrents around 8 mA cm-2 at 1.23 VRHE for water oxidation. Moreover, our carbon/graphite protection and NiFeOOH functionalization methods impart days of stability to the photoanodes, easily extended to weeks, compared with seconds in the absence of protection. Regarding photocatalysts made of halide perovskite, we have found novel approaches based on mechanochemical syntheses and antisolvent crystallization to prepare different composites of CsPbBr3 and other perovskites, including Cs2AgBiBr3/bismuthene and Cs3Bi2Br9/g-C3N4, all photocatalytically active in the reduction of CO2. An extended characterization allows us to relate their physical and charge-transfer properties to their performance, providing guidance in their rational design for their optimization and future application.

ELECTROCHMEICAL SYNTHESIS OF TUNGSTEN OXIDE IN CHLORIDE SOLUTIONS FOR ENVIRONMENTAL PHOTOCATALYSIS

The electrochemical behavior of tungsten in chloride electrolytes with various cationic compositions (Na+, K+, Li+, NH4+) under pulse alternating current has been studied. The decisive influence of the nature of the electrolyte on the phase composition of the resulting dispersed products is shown. The use of NH4Cl ensures the formation of pure crystalline WO3 with a particle size of 30–35 nm. The photoelectrochemical activity of the synthesized WO3 in a sulfuric acid medium under simulated solar radiation has been studied. The addition of glycerol to H2SO4 causes a cathodic shift in the oxidation onset potential by 0.25 V and a threefold increase in the maximum photocurrent density. The possibility of using a WO3/FTO photoanode as part of a flow-through photocatalytic fuel cell (fuel - glycerol, air-breathing Pt/C cathode), characterized by excellent stability in an acidic environment and the maximum power density of 64.0 μW cm-2 is shown.

Photoelectro-catalytic oxidation of monoethanolamine: From the study of electrooxidation mechanism to the development of high-efficient Ni-based photoelectro-catalysts

Monoethanolamine (MEA) electrooxidation occurring on Ni catalyst has proven to be a viable tactics for simultaneous MEA degradation and energy recovery. However, the excessively large overpotential (1505 mV) on Ni catalyst either causes high electricity consumption when acquiring H2 from MEA-containing electrolyzer or leads to low energy output when extracting electricity from direct MEA fuel cell. In this context, the reaction mechanism of MEA electrooxidation on Ni-based catalyst is deciphered at first by employing a specially designed three-step electrochemical procedure and in-situ Raman spectroscopy. Electrochemical data deconvolutions indicate the indirect electrochemical-chemical reaction path, via Ni(OH)2/NiOOH mediator, occupies ∼2.5 % of the total catalytic current density at 0.55 V vs. Ag/AgCl and the direct oxidation of MEA ranks the rest ∼97.5 %. To decrease the onset potential of MEA oxidation, a photoelectric-catalytic system including high-efficient Ni-based photoelectric-catalyst, where Ni is intimately coated on TiO2 by in-situ photodeposition to achieve the shortest carrier transport channel between Ni(OH)2 and TiO2, is developed. Results show the overpotential of MEA electrooxidation under illumination significantly drops to 255 mV. Such a Ni@TiO2/FTO electrode also exerts excellent durability toward MEA oxidation.

High‐Voltage Deep Eutectic Solvent Electrolyte with Fluorine‐Substituted Acetamide Additive for Aluminum‐ion Battery

AbstractThe high‐voltage stability of electrolytes profoundly determines electrochemical reactions, which is still one of the major obstacles for developing advanced Al‐ion batteries (AIBs). Herein, a fluorine‐adjustment strategy is proposed to improve the high‐voltage stability of a low‐cost AlCl3/acetamide (AcA) deep eutectic solvent electrolyte. By using a fluorine‐substituted AcA additive, the AlCl3/AcA electrolyte exhibits a lifted oxidation onset potential from 2.21 to 2.78 V versus Al3+/Al. Based on a series of structural investigations, it is found that the additive can adjust the coordination configurations and improve the anti‐oxidation capability of electrolytes. Moreover, the additive induces an F‐rich interphase layer, which can stabilize the plating/stripping reactions of Al electrode with accelerated kinetics. Based on the optimized electrolyte, a high‐voltage Al–S battery relying on the S cationic redox shows good performance with little voltage fading for 300 cycles. This study provides important insights into the exploration of high‐performance and low‐cost electrolytes for AIBs.

Synergistic effect between the iron (III) oxyhydroxide and Gd-Fe2O3 photoanode interface resulted in an ultra-low onset potential for photoelectrochemical water oxidation

The onset potential is an important descriptor of the photoelectrochemical water oxidation performance of photoanodes. Herein, we prepared Gd-doped hematite (Gd-Fe2O3)/iron (III) oxyhydroxide (FeOOH) core-shell photoanodes by in-situ isovalent doping and secondary hydrothermal treatment. This Gd-Fe2O3/FeOOH photoanode shows a record alkaline water oxidation onset potential (0.59 V vs. reversible hydrogen electrode) in hematite-based photoanodes and a 2.4-fold increase in photocurrent density over pristine hematite. Detailed studies demonstrate that the origin of the ultra-low onset potential is mainly attributed to the synergistic effect of isovalent Gd-doping and FeOOH cocatalyst. Specifically, Gd doping enhances donor density and reduces charge transport resistance, and FeOOH cocatalyst significantly improves water oxidation kinetics. In addition, the strong interfacial coupling of FeOOH and Gd-Fe2O3 promotes electron flow, which also improves the charge separation remarkably. This work gives hope for the achievement of stable and bias-free hematite-based photoanodes.

Bio-mimetic selectivity in Hg2+ sensing developed via electro-copolymerized PEDOT and benzothiazole-Au nanoparticles composite.

To eliminate the potential health risksof mercury, development of stable and selective mercury sensor with high sensitivity is the need of the hour. To address this, a novel PEDOT-AA-BTZ-Au-based Hg2+ selective, hybrid electrochemical sensor has been designed by following a simple protocol for electrode fabrication. The electrode was designed by carefully optimizing the onset oxidation potential of supramolecule 2-(anthracen-9-yl)benzo[d]thiazole (AA-BTZ) and conducting polymer poly-(3,4-ethylenedioxythiophene) (PEDOT), using copolymerization approach followed by dropcasting of gold nanoparticles (AuNPs). The designed electrode offered synergistic effects thus augmenting the electrical conductivity and adsorption capacity as depicted by its porous surface morphology. The highly sensitive analytical signal was generated by sulphur pockets present in AA-BTZ and PEDOT conducting framework. This is further complemented by the selectivity offered by the soft interactions between AuNPs and Hg2+ resulting in a low detection limit of 0.60 nM. The prepared system was further utilized for sensing Hg2+ ion in real systems including lake water and cosmetic samples. Lowinterference from other ions and better reproducibility further established the suitability of the designed transducer system for future on-site sensing.

Chemical deposition from a liquid crystal template: A highly active mesoporous nickel phosphate electrocatalyst for hydrogen green production via urea electro-oxidation in an alkaline solution

Recently the urea and urinated wastewater electrolysis process has shown promising technology for hydrogen fuel green production in addition to denitrification of wastewater. However, to make the process economically valuable, the electrocatalysts nanoarchitecture, nanometer size, shape, facets, and composition need to be engineered to boost the urea oxidation reaction (UOR). This work demonstrates a simple and novel approach to the synthesis of mesoporous nickel phosphate nanoparticles (meso-NiPO) via chemical deposition from a surfactant liquid crystal template. Typically, the nickel ions dissolved in the aqueous domain of the hexagonal liquid crystalline phase of the Brij®78 template were chemically reacted with the sodium phosphate solution to precipitate the mesoporous nickel phosphate nanoarchitecture after washing up the surfactant. The physicochemical characterizations show the meso-NiPO exhibits an amorphous highly mesoporous structure with a higher specific surface area (43.50 m2/g) compared to the bare nickel phosphate (bare-NiPO, 4.26 m2/g) prepared in the absence of surfactant. The electrochemical performance of meso-NiPO electrocatalyst for the urea oxidation reaction in alkaline solution exhibits superior activity including a lower oxidation onset potential (0.30 V vs. Ag/AgCl), charge transfer resistance (3.35 O) and mass activity of 700.7 mA/cm2 mg at the oxidation potential of 0.6 V vs. Ag/AgCl. Moreover, the meso-NiPO reveals long-term stability, and 97.5% of the steady-state oxidation current was maintained after the 3-hour urea electrolysis test. Using an H-shape urea electrolyzer, the corresponding cathodic hydrogen production rate reached 415 µmol/h and a Faradic efficiency of 96.8 % at an applied bias of 2.0 V. The electroactivity high performance of the mesoporous nickel phosphate is ascribed to the high specific surface area and mesoporous architecture that provide efficient charge transfer, as well as mass transport of the electroactive species. The chemical deposition from a surfactant liquid crystal template has the advantages of a one-pot template, applicable to the synthesis of a wide range of nanomaterials with various compositions and nanoarchitectures at room temperature for application in electrochemical energy production and storage systems.

Value-Added Electrolysis Hydrogen Production Via Anodic Oxidation of Ethylene Glycol over an Efficient Pd-Based Single-Atom Catalyst

A promising way of generating hydrogen is electrochemical water splitting for future sustainable green energy source technology options to replace nonrenewable and environmentally pollutant hydrocarbon energy sources. However, the anodic oxygen evolution reaction (OER) is the leading resource of high energy consumption due to its high overpotential. Notably, the generated O2 at the anode side is less needed in practical use. Based on this, why not consider looking for anodic reactions with lower energy consumption and forming value-added products during electrolysis? Ethylene glycol oxidation (EGO) as a small organic molecule is one of the candidates to match the consideration. Therefore, we developed a Pd-based single-atom catalyst prepared via the electrochemical method. The Pd-based single-atom catalyst exhibits excellent EGO activity compared to the commercial Pd/C. In addition, it possesses excellent glycolate selectivity (above 88%) in an alkaline solution with an onset oxidation potential as low as 0.6 V (vs. RHE), much lower than 1.23 V (vs. RHE) of H2O/O2 equilibrium potential. As a result, this work shows a new strategy for electrochemical hydrogen production at far lower anodic potential by designing a stable and efficient Pd-based single-atom catalyst.

Synthesis of Ni-Cu Alloy Supported on Poly(phenylenediamine) As Catalysts for Hydrogen Evolution Reaction

Finding sustainable alternatives for fossil fuels, which are responsible of the climate change is crucial. Hydrogen is a promising solution as a non-polluting fuel cell energy vector [1]. Synthetizing a new electrocatalysts is a promising approach to improve the splitting water without using high cost platinum metal [2]. In this context, several research have been conducted on alloy such as Ni-Co, Ni-Fe and Ni-Mo [3] as electrocatalyst for Hydrogen evolution reaction (HER). Herein, A simple and one step deposition method was used for the first time to synthesis a new catalyst composed of Nickel and Copper and Poly(Para-phenylediamine) for HER . A comparative study was conducted with three conjugated polymers based on Poy(phenylenediamine) [4], which were used as a support prior to the deposition of the Ni-Cu alloy by a very simple approach. The morphology and structure of the prepared catalysts were characterized by field emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD). The performance of the catalyst for the hydrogen evolution reaction was examined in alkaline medium by linear sweep voltammetry (LSV), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). Reference : [1] L’ONU annonce un réchauffement climatique de 2,6°C à cause d’engagements des États “pitoyablement pas à la hauteur,” Marie Claire. (2022). https://www.marieclaire.fr/rapport-de-l-onu-sur-le-climat-vers-un-rechauffement-de-2-6-c-a-cause-d-engagements-pitoyablement-pas-a-la-hauteur-des-etats,1435999.asp (accessed January 31, 2023).[2] I. Herraiz-Cardona, E. Ortega, J. Garcı´a Anto´n, V. Pe´rez-Herranz. Assessment of the roughness factor effect and the intrinsic catalytic activity for hydrogen evolution reaction on Ni-based electrodeposits, ª 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. https://doi.org/10.1016/j.ijhydene.2011.05.047[3] H. Li, G. Gao, H. Zhao, W. Wang, Y. Yang, Y. Du, S. Li, Y. Liu, L. Wang, Rational design of free-standing 3D Cu-doped NiS@Ni2P/NF nanosheet arrays for hydrogen evolution reaction, International Journal of Hydrogen Energy. 46 (2021) 33078–33086. https://doi.org/10.1016/j.ijhydene.2021.07.059.[4] S. Chemchoub, A. El Attar, L. Oularbi, S.A. Younssi, F. Bentiss, C. Jama, M. El Rhazi, Electrosynthesis of eco-friendly electrocatalyst based nickel-copper bimetallic nanoparticles supported on poly-phenylenediamine with highest current density and early ethanol oxidation onset potential, International Journal of Hydrogen Energy. 47 (2022) 39081–39096. https://doi.org/10.1016/j.ijhydene.2022.09.069.