Hydrogen Electrode Research Articles

Coupling In nanoclusters and Bi nanoparticles in nitrogen-doped carbon for enhanced CO2 electroreduction to HCOOH

CO2 electrochemical reduction reaction (CO2RR) to formic acid (HCOOH) is beneficial for the recycling of carbon resources, which needs the highly selective catalysts with long-term stability for HCOOH production. In this study, the coupling of In nanoclusters (Inclus) and Bi nanoparticles (Binps) in nitrogen-doped carbon was designed by the thermal decomposition of the mixture of bimetallic MOFs and dicyanamide. When the In/Bi molar ratio was 1:2 (Inclus/Binps-1:2), the hybrid catalyst achieved a HCOOH Faradaic efficiency (FEHCOOH) of 94.5 % at −1.1 V vs reversible hydrogen electrode (RHE) in an H-type electrolysis cell, superior to that of single metal counterparts. Moreover, the Inclus/Binps-1:2 can maintain high stability of structures during the catalytic process, leading to no significant decay of FEHCOOH over 32 h. The enhanced performance of Inclus/Binps-1:2 is attributed to the strong electron interactions induced by the charge transfer between the In and Bi sites in Inclus/Binps-1:2 catalyst. The tuned electronic structure results in an offset effect that optimizes the binding energy to HCOO* intermediate, thus accelerating the CO2 to HCOOH conversion, as proven by the in-situ ATR-SEIRAS and density functional theory (DFT) calculations.

Boosting electrocatalytic oxygen reduction of Fe-Co polyphthalocyanine via the synergy of metal component optimization and axial ligand modification

Conjugated metal polyphthalocyanine (MPPc) organic skeletons, a kind of novel porous materials containing inherent M−N4 highly active sites, are of great significance for oxygen reduction reaction (ORR). Herein, bimetallic Fe-Co phthalocyanine covalent polymers (denoted as FeCoPPc) were prepared as ORR electrocatalysts through a solvothermal process and subsequent oxidation treatment. Meanwhile, the effect of axial oxygen-containing ligands of metal centers on the catalytic kinetic processes was also investigated. Benefiting from the highly exposed bimetal active sites and the finely designed ligand structure, FeCoPPc with optimized Fe/Co ratio and ClO3− coordination (Fe0.9Co0.1PPc-ClO3) displayed an outstanding ORR electrocatalytic activity and superior durability compared to 20 % Pt/C, manifested by an onset potential of 0.986 V vs. reversible hydrogen electrode (RHE) and a half-wave potential of 0.923 V vs. RHE in a 0.1 M KOH solution. This work may guide the rational design of high-performance electrocatalysts to regulate the catalytic activity.

N-ZrS3/p-ZrOS Photoanodes with NiOOH/FeOOH Oxygen Evolution Catalysts for Photoelectrochemical Water Oxidation.

Photoelectrochemical water splitting offers a promising approach for carbon neutrality, but its commercial prospects are still hampered by a lack of efficient and stable photoelectrodes with earth-abundant materials. Here, we report a strategy to construct an efficient photoanode with a coaxial nanobelt structure, comprising a buried-ZrS3/ZrOS n-p junction, for photoelectrochemical water splitting. The p-type ZrOS layer, formed on the surface of the n-type ZrS3 nanobelt through a pulsed-ozone-treatment method, acts as a hole collection layer for hole extraction and a protective layer to shield the photoanode from photocorrosion. The resulting ZrS3/ZrOS photoanode exhibits light harvesting with good photo-to-current efficiencies across the whole visible region to over 650 nm. By further employing NiOOH/FeOOH as the oxygen evolution reaction cocatalyst, the ZrS3/ZrOS/NiOOH/FeOOH photoanode yields a photocurrent density of ~9.3 mA cm-2 at 1.23 V versus the reversible hydrogen electrode with an applied bias photon-to-current efficiency of ~3.2% under simulated sunlight irradiation in an alkaline solution (pH = 13.6). The conformal ZrOS layer enables ZrS3/ZrOS/NiOOH/FeOOH photoanode operation over 1000 hours in an alkaline solution without obvious performance degradation. This study, offering a promising approach to fabricate efficient and durable photoelectrodes with earth-abundant materials, advances the frontiers of photoelectrochemical water splitting.

Boron-Doping Engineering in AgCd Bimetallic Catalyst Enabling Efficient CO2 Electroreduction to CO and Aqueous Zn-CO2 Batteries.

The limited adsorption and activation of CO2 on catalyst and the high energy barrier for intermediate formation hinder the development of electrochemical CO2 reduction reactions (CO2RR). Herein, this work reports a boron (B) doping engineering in AgCd bimetals to alleviate the above limitations for efficient CO2 electroreduction to CO and aqueous Zn-CO2 batteries. Specifically, the B-doped AgCd bimetallic catalyst (AgCd-B) is prepared via a simple reduction reaction at room temperature. A combination of in situ experiments and density functional theory (DFT) calculations demonstrates that B-doping simultaneously enhances the adsorption and activation of CO2 and reduces the binding energy of the intermediates by moderating the electronic structure of bimetals. As a result, the AgCd-B catalyst exhibits a high CO Faraday efficiency (FECO) of 99% at -0.8V versus reversible hydrogen electrode (RHE). Additionally, it maintains a FECO over 92% at a wide potential window of 600mV (-0.6 to -1.1V versus RHE). Furthermore, the AgCd-B catalyst coupled with the Zn anode to assemble aqueous Zn-CO2 batteries shows a power density of 20.18mW cm-2 and a recharge time of 33h.

Oxophilic Sn to promote glucose oxidation to formic acid in Ni nanoparticles.

The electrochemical glucose oxidation reaction (GOR) presents an opportunity to produce hydrogen and high-value chemical products. Herein, we investigate the effect of Sn in Ni nanoparticles for the GOR to formic acid (FA). Electrochemical results show that the maximum activity is related to the amount of Ni, as Ni sites are responsible for catalyzing GOR via the NiOOH/Ni(OH)2 pair. However, the GOR kinetics increases with the amount of Sn, associated with an enhancement of the OH- supply to the catalyst surface for Ni(OH)2 reoxidation to NiOOH. NiSn nanoparticles supported on carbon nanotubes (NiSn/CNT) exhibit excellent current densities and direct GOR via C-C cleavage mechanism, obtaining FA with a Faradaic efficiency (FE) of 93% at 1.45 V vs. reversible hydrogen electrode. GOR selectivity is further studied by varying the applied potential, glucose concentration, reaction time, and temperature. FE toward FA production decreases due to formic overoxidation to carbonates at low glucose concentrations and high applied potentials, while acetic and lactic acids are obtained with high selectivity at high glucose concentrations and 55 °C. Density functional theory calculations show that the SnO2 facilitates the adsorption of glucose on the surface of Ni and promotes the formation of the catalytic active Ni3+ species.

Fine-tuning syngas composition using laser surface modified silver electrode for CO2 electroreduction

Electrochemical reduction of CO2 and H2O to synthesize gas (H2 and CO mixture) is of significant interest due to established industrial pathways to tune the H2 to CO composition to generate an array of valuable products including methanol, synthetic fuel, synthetic natural gas, and hydrogen. However, controlled H2:CO ratios are challenging on CO-active electrocatalysts like silver. We demonstrate that applying laser engineering to adjust the surface wetting state of a silver electrocatalyst with water contact angles θw ranging from 47° and 135°, H2:CO ratios can be tuned from 1 to 4 at modest potentials (−0.7 V versus RHE, RHE—reversible hydrogen electrode) with almost total unity Faradaic efficiency. Both hydrophilic (θw = 47°) and more hydrophobic (θw = 135°) samples showed an increasing H2:CO trend with rising potentials (0.7–1.2 V versus RHE) due to mass transport. Conversely, silver electrocatalyst with θw = 110° exhibited a constant H2:CO ratio of 4. This indicates catalyst wettability potentially affects *H and *HOCO intermediates’ adsorption, impacting H2:CO ratios. Our results show the feasibility of syngas composition control on silver catalysts via surface wettability, providing a simpler alternative to complex multicomponent electrocatalytic systems.

Leveraging Soft Acid-Base Interactions Alters the Pathway for Electrochemical Nitrogen Oxidation to Nitrate with High Faradaic Efficiency.

Electrocatalytic nitrogen oxidation reaction (N2OR) offers a sustainable alternative to the conventional methods such as the Haber-Bosch and Ostwald oxidation processes for converting nitrogen (N2) into high-value-added nitrate (NO3 -) under mild conditions. However, the concurrent oxygen evolution reaction (OER) and inefficient N2 absorption/activation led to slow N2OR kinetics, resulting in low Faradaic efficiencies and NO3 - yield rates. This study explored oxygen-vacancy induced tin oxide (SnO2-Ov) as an efficient N2OR electrocatalyst, achieving an impressive Faradaic efficiency (FE) of 54.2% and a notable NO3 - yield rate (22.05µg h-1 mgcat -1) at 1.7V versus reversible hydrogen electrode (RHE) in 0.1m Na2SO4. Experimental results indicate that SnO2-Ov possesses substantially more oxygen vacancies than SnO2, correlating with enhanced N2OR performance. Computational findings suggest that the superior performance of SnO2-Ov at a relatively low overpotential is due to reduced thermodynamic barrier for the oxidation of *N2 to *N2OH during the rate-determining step, making this step energetically favorable than the oxygen adsorption step for OER. This work demonstrates the feasibility of ambient nitrate synthesis on the soft acidic Sn active site and introduces a new approach for rational catalyst design.

Sub‐Nanometer‐Scale Cu9S5 Enables Efficiently Electrochemical Nitrate Reduction to Ammonia

AbstractThe sub‐nanometer is a key feature size in materials science. Unlike single‐atom and nanomaterials, size effects and inter‐component cooperative actions in sub‐nanomaterials will effective on its performance is more significant. Here, 0.95 nm ordered arrangement Cu9S5 sub‐nanowires (Cu9S5 SNWs) are synthesized through the co‐assembly effect of inorganic nuclei (Cu9S5) and clusters (phosphotungstic acid‐PTA), achieving a significant increase in the specific surface area of the sample and ≈100% atomic exposure rate, which is the key to its high catalytic activity. PTA clusters not only act as a “charge transfer station” to accelerate the inter‐component electron transfer process, but also facilitate the dissociation of water and provide more hydrogen protons, thus dramatically facilitating the electrocatalytic process. The experimental results show that the Cu9S5 SNWs exhibited excellent nitrate reduction reaction (NO3−RR) properties. The Faraday efficiency (FE) of NO3−RR is 90.4% at the optimum potential −0.3 VRHE (reversible hydrogen electrode) and the ammonia production is as high as 0.37 mmol h−1 cm−2, which is superior to most reported electrocatalysts. In addition, the Zn‐NO3− liquid‐flow battery devices assembled using Cu9S5 SNWs as electrode materials show excellent application results. This work provides a reference for the design of highly efficient sub‐nanoscale NO3−RR electrocatalysts.

Self-Polycondensation Flux Synthesis of Ultrastable Olefin-Linked Covalent Organic Frameworks for Electrocatalysis.

Creating new functional materials that efficiently support noble metal catalysts is important and in high demand. Herein, we develop a self-polycondensation flux synthesis strategy that can produce olefin-linked covalent organic framework (COF) platforms with high crystallinity and porosity as the supports of Pd nanoparticles for electrocatalytic nitrogen reduction reaction (ENRR). A series of "two in one" monomers integrating aldehyde and methyl reactive groups are rationally designed to afford COFs with square-shaped pores and ultrahigh chemical stability (e.g., strong acid or alkali environments for >1 month). Functionalizing Fluorine significantly boosts the hydrophobicity of fluoro-functionalized COFs, which can inhibit the competing hydrogen evolution reaction (HER) and enhance ENRR performances. The COFs loading Pd nanoparticles show high NH3 production yields up to 90.0 ± 2.6 μg·h-1·mgcat.-1 and the faradaic efficiency of 44% at -0.2 V versus reversible hydrogen electrode, the best comprehensive performance among all reported COFs. Meanwhile, the catalysts are easy to recover and recycle, as demonstrated by their use for 15 cycles and 17 hours, with good performance retention. This work not only provides a new synthesis strategy for olefin-linked COFs, but also paves a new avenue for the design of highly efficient ENRR catalysts.

Copper–nickel–MOF/nickel foam catalysts grown in situ for efficient electrochemical nitrate reduction to ammonia

Reducing nitrate (NO3−) in an aqueous solution to ammonia under ambient conditions can provide a green and sustainable NH3‐synthesis technology and mitigate global energy and pollution issues. In this work, a CuNi0.75–1,3,5‐benzenetricarboxylic acid/nickel foam (CuNi0.75–MOF/NF) catalyst grown in situ was prepared via a one‐pot method as an efficient cathode material for electrocatalytic nitrate reduction reaction (NO3RR). The CuNi0.75–MOF/NF catalyst exhibited excellent electrocatalytic NO3RR performance at −1.0 V versus a reversible hydrogen electrode, achieving an outstanding faradaic efficiency of 95.88 % and an NH3 yield of 51.78 mg h−1 cm−2. The 15N isotope labeling experiments confirmed that the sole source of N in the electrocatalytic NO3RR was the NO3− in the electrolyte. The reaction pathway for the electrocatalytic NO3RR was derived by in situ Fourier transform infrared spectroscopy and in situ differential electrochemical mass spectrometry. Density functional theory calculations revealed that the Ni element in the CuNi0.75–MOF/NF catalyst had excellent O–H activation ability and strong *H adsorption capacity. These *H species were transferred from the Ni sites to the *NO adsorption intermediates located on the Cu sites, providing a continuous supply of *H to Cu, thereby promoting the formation of *NOH intermediates and enhancing the hydrogenation process of the electrocatalytic NO3RR.

Carbothermal Reduction-Assisted Synthesis of a Carbon-Supported Highly Dispersed PtSn Nanoalloy for the Oxygen Reduction Reaction.

Exploring high-performance and low-platinum-based electrocatalysts to accelerate the oxygen reduction reaction (ORR) at the air cathode of zinc-air batteries remains crucial. Herein, by combining electroless deposition and carbothermal reduction, a nitrogen-doped carbon-supported highly dispersed PtSn alloy nanocatalyst (PtSn/NC) was prepared for a high-efficiency ORR process. Electrochemical measurements show that PtSn/NC exhibits excellent electrocatalytic ORR activity with a half-wave potential of 0.850 V versus reversible hydrogen electrode (RHE), which is higher than that of commercial Pt/C (0.815 V). The PtSn/NC-based (20 μgPt cm-2) rechargeable Zn-air battery exhibited astonishing performance with a maximum power density of up to 150.1 mW cm-2, as well as excellent rate performance and charge/discharge stability. Physical characterization reveals that carbothermal reduction could compel the transformation of Sn oxide into metallic Sn, which then alloys with the deposited Pt atoms to form the PtSn nanoalloy, in which electrons are transferred from Sn atoms to neighboring Pt atoms, thereby improving the ability of Pt-based active sites to catalyze the ORR process in PtSn/NC by optimizing the unoccupied d-band of Pt atoms. This work provides a reliable and innovative route for the rational design of highly dispersed Pt-based alloy ORR electrocatalysts.

In-situ electrochemical reconstruction and modulation of adsorbed hydrogen coverage in cobalt/ruthenium-based catalyst boost electroreduction of nitrate to ammonia

The electroreduction of nitrate offers a promising, sustainable, and decentralized route to generate valuable ammonia. However, a key challenge in the nitrate reduction reaction is the energy efficiency of the reaction, which requires both a high ammonia yield rate and a high Faradaic efficiency of ammonia at a low working potential (≥−0.2 V versus reversible hydrogen electrode). We propose a bimetallic Co–B/Ru12 electrocatalyst which utilizes complementary effects of Co–B and Ru to modulate the quantity of adsorbed hydrogen and to favor the specific hydrogenation for initiating nitrate reduction reaction at a low overpotential. This effect enables the catalyst to achieve a Faradaic efficiency for ammonia of 90.4 ± 9.2% and a remarkable half-cell energy efficiency of 40.9 ± 4% at 0 V versus reversible hydrogen electrode. The in-situ electrochemical reconstruction of the catalyst contributes to boosting the ammonia yield rate to a high level of 15.0 ± 0.7 mg h−1 cm−2 at −0.2 V versus reversible hydrogen electrode. More importantly, by employing single-entity electrochemistry coupled with identical location transmission electron microscopy, we gain systematic insights into the correlation between the increase in the catalyst’s active sites and its structural transformations during the nitrate reduction reaction.

Stabilizing In/InN intermediates by electron-deficient carbon for improved CO2 electroreduction to CO

Monitoring and stabilizing the reconstructed active material under operational conditions is crucial for the rational design of electrocatalysts. Herein, we developed a novel hinged structure composited by the electron-deficient carbon and InN nanorods (InN@C) for preserving the high-active In/InN interfaces under electrochemical CO2 reduction process. The electron-deficient carbon, caused by the interfacial rectifying effect, prevents active site annihilation and deep self-reduction of In/InN, leading to synergistic improvements in catalytic activity and long-term stability. Mechanistic studies show that an interfacial dipole between the electron-deficient carbon layer and In/InN promotes CO2 activation and strengthens In−N bonds, inhibiting the deep self-reduction of In/InN. As a result, we achieved remarkable long-term stability of 150 hours, with a Faradaic efficiency of 92 % and a current density of ∼ 40 mA cm−2 at − 0.8 V versus the reversible hydrogen electrode. This study offers a practical approach to preserve the high-active intermediates for synergistically improving the catalytic activity and long-term stability of transition metal compound electrocatalysts.

Ag Nanoparticles-Confined Doped within Triazine-Based Covalent Organic Frameworks for Syngas Production from Electrocatalytic Reduction of CO2.

Electrocatalytic CO2 reduction reaction (CO2RR) emerges as a promising avenue to mitigate carbon emissions, enabling the capture and conversion of CO2 into high-value products such as syngas with CO/H2. One of the crucial aspects lies in the tailored development of durable and efficient electrocatalysts for the CO2RR. Covalent organic frameworks (COFs) possess unique characteristics that render them attractive candidates for catalytic applications. However, the relationship between structure and performance still requires further exploration; especially, most COFs with such properties are limited to COFs containing specific groups such as phthalocyanine or porphyrin groups. Here, we custom-synthesize two azine-linked nitrogen-rich COFs constructed from triazine building blocks, which are doped with ultrafine and highly dispersed Ag nanoparticles (Ag@TFPT-HZ and Ag@TPT-HZ). Thus-obtained COFs can serve as electrocatalysts for the CO2RR, and a comprehensive investigation has been conducted to uncover the intricate structure-performance relationship within these materials. Notably, Ag@TFPT-HZ exhibits superior CO selectivity in the electrocatalytic CO2RR, achieving a FECO of 81% and a partial current density of 7.65 mA·cm-2 at the potential of -1.0 V (vs reversible hydrogen electrode (RHE)). In addition, Ag@TPT-HZ as an electrocatalyst can continuously produce syngas with a CO/H2 molar ratio of 1:1, an ideal condition for methanol synthesis. The observed distinct performance between these two COFs is attributed to the presence of O atoms in TFPT-HZ. These O atoms facilitate a higher loading capacity of Ag nanoparticles (11 wt %) and generate a greater number of active sites, thereby enhancing electrochemical activity and promoting faster reaction kinetics. Therefore, two tailor-made two-dimensional (2D) nitrogen-rich COFs with various active sites as electrocatalysts can exhibit different outstanding electrocatalytic performances for CO2RR and possess high cycling stability (>50 h). This work offers valuable insights into the design and synthesis of electrocatalysts, particularly in elucidating the intricate relationship between their structure and performance.

Electrocatalytic dechlorination of chloroethylenes using nitrogen-doped graphene electrodes

Electro-dehalogenation for the clean-up of carcinogenic chloroethylenes (CEs) in groundwater is hindered by the high operating costs of metal electrodes and low efficiency due to competing water reduction and hydrogen formation. This study prepared metal-free electrodes with high Faradaic efficiency (FE) up to 50 % in aqueous solution by coating nitrogen-doped graphene nanoplatelets (N-GPs) on carbon paper. Dechlorination rates at these N-GPs electrodes were enhanced by ∼15 times compared with the plain graphene-based electrode, with first-order rate constants of 0.28, 0.33, 0.41, and 0.048 h−1 for tetrachloroethylene (PCE, 22 μM), trichloroethylene (TCE, 22 μM), cis-dichloroethylene (cis-DCE, 22 μM), and vinyl chloride (VC, 11 μM) dechlorination to acetylene and ethene (VC), respectively, at −1.0 V vs standard hydrogen electrode (SHE), and initial neutral pH. Surprisingly, extremely low N or no-N containing GP was detected from highly reactive N-GPs. Despite the N-doping process has been wildly used for improving electrocatalytic reactivity of catalysts by inducing N-functional groups, this study suggests that, the polygonal intrinsic defects formed after N burn-off may act as dechlorination active sites. The N-GP electrodes showed appreciable stable performance over 24 h (five cycles). Simultaneous electrolysis of a mixture of CEs in groundwater without the addition of supporting electrolytes achieved >90 % reduction of PCE, TCE, and cis-DCE and ∼60 % reduction of VC within 24 h at −1.23 V vs SHE, demonstrating its superior performance and great potential of these electrodes in practical applications.

Enhanced Hydrogen Evolution Reaction Activity through Bimetallic Phosphide Integration in ReS2/Re2O7 Heterostructure

AbstractDeveloping a nonprecious and sustainable electrocatalyst in clean energy generation is quite noteworthy. Transition metal chalcogenides, oxides, and phosphides have emerged as promising candidates to substitute Pt‐based catalysts. In this study, we explore the catalytic potential of ReS2, a promising member of the transition metal dichalcogenides (TMD) family, for hydrogen evolution reactions (HER). The formation of rhenium oxide during the synthesis of ReS2 and further incorporation of a bimetallic phosphide NiCuP in a sequential hydrothermal synthesis reveals an excellent HER activity, as demonstrated by photoelectrochemical and electrochemical studies. Notably, the catalyst exhibits a significantly lower overpotential of −0.10 V (corresponding to −10 mA/cm2) and achieves a high current density of approx. −271 mA/cm2 at −0.79 V versus reversible hydrogen electrode (RHE) under light irradiation. The catalyst demonstrates high stability. These findings underscore the potential of NiCuP‐integrated ReS2/Re2O7 as a highly efficient and sustainable catalyst for HER.

Strong metal-support interaction induced by oxygen vacancies to enhance the activity and durability of Pt/TiO2/ hollow carbon nanospheres ORR catalyst

For the commercial Pt-loaded carbon ORR catalysts used in proton exchange membrane fuel cells (PEMFC), carbon support corrosion, along with the migration and aggregation of Pt nanoparticles (NPs) due to the weak interaction between Pt NPs and carbon, leads to a drastic reduction in both electrocatalytic activity and stability. Hence, exploring active and steady supports is crucial to restrain the activity loss and stabilize Pt catalysts. In this work, a composite support consisting of hollow carbon nanospheres (HC) and TiO2 NPs with abundant oxygen vacancies (OV) loaded with Pt NPs (PTHC-H) was designed and synthesized. Experiment results show that PTHC-H exhibits superior activity and stability compared to PTHC-N (TiO2 with lower OV content) and commercial Pt/C catalyst. Specifically, PTHC-H delivers a half-wave potential of 0.883V versus reversible hydrogen electrode. And its mass activity and half-wave potential decrease by only 15.96% and 7mV, respectively, after 10,000 cycles of accelerated durability testing. The excellent activity and stability are ascribed to the enhanced metal-support interaction induced by OV, which can optimize the Pt d-band center and suppresses the migration and aggregation of Pt NPs. This work may be favorable for designing efficient and durable anti-corrosion nano catalysts.

Sulfur doping and oxygen vacancy in In2O3 nanotube co-regulate intermediates of CO2 electroreduction for efficient HCOOH production and rechargeable Zn-CO2 battery

By manipulating the distribution of surface electrons, defect engineering enables effective control over the adsorption energy between adsorbates and active sites in the CO2 reduction reaction (CO2RR). Herein, we report a hollow indium oxide nanotube containing both oxygen vacancy and sulfur doping (Vo-Sx-In2O3) for improved CO2-to-HCOOH electroreduction and Zn-CO2 battery. The componential synergy significantly reduces the *OCHO formation barrier to expedite protonation process and creates a favorable electronic micro-environment for *HCOOH desorption. As a result, the CO2RR performance of Vo-Sx-In2O3 outperforms Pure-In2O3 and Vo-In2O3, where Vo-S53-In2O3 exhibits a maximal HCOOH Faradaic efficiency of 92.4% at −1.2 V vs. reversible hydrogen electrode (RHE) in H-cell and above 92% over a wide window potential with high current density (119.1 mA cm−2 at −1.1 V vs. RHE) in flow cell. Furthermore, the rechargeable Zn-CO2 battery utilizing Vo-S53-In2O3 as cathode shows a high power density of 2.29 mW cm−2 and a long-term stability during charge-discharge cycles. This work provides a valuable perspective to elucidate co-defective catalysts in regulating the intermediates for efficient CO2RR.

Stabilizing High-Valence Copper(I) Sites with Cu-Ni Interfaces Enhances Electroreduction of CO2 to C2+ Products.

In this study, the copper-nickel (Cu-Ni)bimetallic electrocatalysts for electrochemical CO2 reduction reaction(CO2RR) are fabricated by taking the finely designed poly(ionic liquids) (PIL) containing abundant Salen and imidazolium chelating sites as the surficial layer, wherein Cu-Ni, PIL-Cu and PIL-Ni interaction can be readily regulated by different synthetic scheme. As a proof of concept, Cu@Salen-PIL@Ni(NO3)2 and Cu@Salen-PIL(Ni) hybrids differ significantly in the types and distribution of Ni species and Cu species at the surface, thereby delivering distinct Cu-Ni cooperation fashion for the CO2RR. Remarkably, Cu@Salen-PIL@Ni(NO3)2 provides a C2+ faradaic efficiency (FEC2+) of 80.9% with partial current density (jC 2+) of 262.9mA cm-2 at -0.80V (versus reversible hydrogen electrode, RHE) in 1m KOH in a flow cell, while Cu@Salen-PIL(Ni) delivers the optimal FEC2+ of 63.8% at jC2+ of 146.7mAcm-2 at -0.78V. Mechanistic studies indicates that the presence of Cu-Ni interfaces in Cu@Salen-PIL@Ni(NO3)2 accounts for the preserve of high-valence Cu(I) species under CO2RR conditions. It results in a high activity of both CO2-to-CO conversion and C-C coupling while inhibition of the competitive HER.

General Design of Aligned-Channel Porous Carbon Electrodes for Efficient High-Current-Density Gas-Evolving Electrocatalysis.

Gas-evolving reactions (GERs) are important in many electrochemical energy conversion technologies and chemical industries. The operation of GERs at high current densities is critical for their industrial implementation but remains challenging as it poses stringent requirements on the electrodes in terms of reaction kinetics, mass transfer, and electron transport. Here the general and rational design of self-standing carbon electrodes with vertically aligned porous channels, appropriate pore size distribution, and high surface area as supports for loading a variety of catalytic species by facile electrodeposition are reported. These electrodes simultaneously possess high intrinsic activity, large numbers of active sites, and efficient transport highways for ions, gases, and electrons, resulting in significant performance improvements at high current densities in diverse GERs such as urea oxidation, hydrogen evolution, and oxygen evolution reactions, as well as overall urea/water electrolyzers. As an example, the carbon electrode decorated with Ni(OH)2 demonstrates a record-high current density of 1000mAcm-2 at 1.360V versus the reversible hydrogen electrode, largely outperforming the conventional nickel foam-based counterpart and the state-of-the-art electrodes.