Non-noble Metal Electrocatalysts Research Articles

Ultra-fast synthesis of transition metal-MXene nanocomposite electrocatalyst for energy-saving seawater hydrogen production: Experiment and theory

Switching from the urea oxidation reaction (UOR) to the oxygen evolution reaction (OER) is a beneficial way to lower the amount of energy needed to make hydrogen gas during the hydrogen evolution reaction (HER). Due to the sluggish reaction kinetics of the six electrons reaction of UOR, designing a privileged bifunctional electrocatalyst for both HER and UOR necessitates. The 2D nano-sized non-noble metal electrocatalysts make it possible to speed up reactions and improve their electrocatalytic performance. We synthesized nickel-cobalt-MXene composite nanosheets (NiCoMXene) on the surface of copper foam using a one-pot, simple, and ultra-fast electrochemical method. This 2D electrocatalyst demonstrates high electrocatalytic performance towards HER (overpotential of 76 mV at −10 mA cm−2) with excellent durability in alkaline media. Furthermore, NiCoMXene nanocomposite served as a bifunctional electrocatalyst to investigate hydrogen gas production by a hybrid system HER coupled with UOR in seawater. The NiCoMXene requires a low overpotential for HER (81 mV) and UOR (1.38 V) to achieve a current density of 10 mA cm−2 in seawater, and the needed cell voltage to reach the same current density is 1.42 V in seawater. Our DFT analysis found a significant synergy between MXene and NiCo in the electrocatalyst. PDOS analysis showed remarkably that introducing Ni atoms to MXene shifts the d-band center to the left (lower energy), while Co atoms shifts it to the right (higher energy) and increased states near the Fermi level. This electronic structure makes the nanocomposite an ideal electrocatalyst, with MXene providing electrons and Co atoms serving as active sites for both HER and UOR.This research work can provide a useful directive to explore the electrocatalysts with outstanding catalytic activity.

Theoretical Investigation of Single-, Double-, and Triple- p-block Metals Anchored on g-CN Monolayer for Oxygen Electrocatalysis.

The design and development of highly active non-noble metal electrocatalysts for the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) are crucial for metal-air batteries. In this work, the electrocatalytic performance of different p-block metal (PM = Sn, Sb, Pb and Bi) atoms embedded in the g-CN monolayer (PMx@g-CN, x = 1-3) for the OER and ORR was systematically investigated by density functional theory (DFT). The strong interaction between PMx atoms and g-CN substrates indicates the good stability of PMx@g-CN catalysts. Among all the designed catalysts, Bi3@g-CN is found to be a promising bifunctional electrocatalyst for both the OER and ORR with the calculated overpotential ηOER and ηORR of 0.23 and 0.25 V, respectively. With the atomic active sites of PMx increasing from x = 1 to 3, the OER and ORR catalytic activity is enhanced. The correlations between the overpotentials of the OER/ORR and Bader charge values of the anchored PMx atoms of the catalysts were established. Our findings contribute to searching for noble metal-free bifunctional electrocatalysts and shed light on the rational design of atomic active sites on electrocatalysts.

Non-Noble Metal Catalysts for Electrooxidation of 5-Hydroxymethylfurfural.

2,5-Furandicarboxylic acid (FDCA) is a class of valuable biomass-based platform compounds. The creation of FDCA involves the catalytic oxidation of 5-hydroxymethylfurfural (HMF). As a novel catalytic method, electrocatalysis has been utilized in the 5-hydroxymethylfurfural oxidation reaction (HMFOR). Common noble metal catalysts show catalytic activity, which is limited by price and reaction conditions. Non-noble metal catalyst is known for its environmental friendliness, affordability and high efficiency. The development of energy efficient non-noble metal catalysts plays a crucial role in enhancing the HMFOR process. It can greatly upgrade the demand of industrial production, and has important research significance for electrocatalytic oxidation of HMF. In this paper, the reaction mechanism of HMF undergoes electrocatalytic oxidation to produce FDCA are elaborately summarized. There are two reaction pathways and two oxidation mechanisms of HMFOR discussed deeply. In addition, the speculation on the response of the electrode potential to HMFOR is presented in this paper. The main non-noble metal electrocatalysts currently used are classified and summarized by targeting metal element species. Finally, the paper focus on the mechanistic effects of non-noble metal catalysts in the reaction, and provide the present prospects and challenges in the electrocatalytic oxidation reaction of HMF.

A strongly coupled 1T'-ReSe2@2H-MoSe2 van der Waals heterostructure for efficient electrocatalytic hydrogen evolution at high current densities.

Developing efficient and durable non-noble metal electrocatalysts for high current-density hydrogen evolution reactions (HER) is a pressing requirement for commercial industrial electrolyzers. In this study, a vertical 1T'-ReSe2@2H-MoSe2 van der Waals heterostructure was developed through interface engineering to enhance the advantages of each component and expose numerous active sites. Experimental investigations and density functional theorycalculations demonstrate significant electronic coupling at the interface between 1T'-ReSe2 and 2H-MoSe2, with suitable Gibbs free energy for hydrogen adsorption. The 1T'-ReSe2@2H-MoSe2 heterostructure catalyst achieves high current density HER with low overpotentials of 191 mV to generate up to 800 mA/cm2 in 0.5 M H2SO4, outperforming commercial 5% Pt/C catalysts. Moreover, this catalyst exhibits rapid reaction kinetics and long-term durability, illustrating a successful approach to designing efficient heterostructure electrocatalysts for hydrogen production through interface engineering.

Pyrolysis of Copper Phthalocyanine as Non-noble Metal Electrocatalysts for Oxygen Reduction Reaction

Pyrolysis of Copper Phthalocyanine as Non-noble Metal Electrocatalysts for Oxygen Reduction Reaction

One-pot synthesis of FeNi3/FeNiOx nanoparticles for PGM-free anion exchange membrane water electrolysis

Low-temperature anion exchange membrane water electrolysis (AEMWE) is one of the most promising technologies to produce green hydrogen. To date, membrane-electrode assembly (MEA) based on platinum group metal (PGM) electrocatalysts shows higher performance than PGM-free ones. Here, a single and easy synthesis for non-noble metal electrocatalysts (PGM-free) for both hydrogen and oxygen evolution reactions (HER and OER) was developed. Both electrocatalysts consist of FeNi3/FeNiOx nanoparticles obtained through chemical reduction using hydrazine. The electrocatalyst exhibits an overpotential of 210 mV and 234 mV for HER and OER respectively, at a current density of 10 mA cm−2 in 1 M KOH electrolyte, allowing a comparison between mass activity and geometric activity compared to PGM catalysts. In addition to a preliminary electrochemical characterization of the FeNi3/FeNiOx, the electrocatalyst were integrated into a pilot-scale AEMWE at both anode and cathode, which reaches (without iR-correction) 1.72 V and 1.94 V at a current density of 0.4 A cm−2 and 1 A cm−2 respectively at 60 °C. This PGM-free MEA outperforms the one based on Pt/C at cathode and RuO2 at anode with a voltage gap of 284 mV at 1 A cm−2. The aforementioned MEA was tested for 150 h with a discontinuous power profile, in order to get an idea of the possible degradation trends for a future industrial application, the reversible and irreversible voltage losses were calculated resulting in a degradation rate of 886 µV/h. This work demonstrates a simple and scalable synthesis of earth-abundant electrocatalytic materials for high-efficiency AEM water electrolysis.

Nanoarchitectonics of Fe-Doped Ni3S2 Arrays on Ni Foam from MOF Precursors for Promoted Oxygen Evolution Reaction Activity.

Oxygen evolution reaction (OER) is a critical half-reaction in electrochemical overall water splitting and metal-air battery fields; however, the exploitation of the high activity of non-noble metal electrocatalysts to promote the intrinsic slow kinetics of OER is a vital and urgent research topic. Herein, Fe-doped Ni3S2 arrays were derived from MOF precursors and directly grown on nickel foam via the traditional solvothermal way. The arrays integrated into nickel foam can be used as self-supported electrodes directly without any adhesive. Due to the synergistic effect of Fe and Ni elements in the Ni3S2 structure, the optimized Fe2.3%-Ni3S2/NF electrode delivers excellent OER activity in an alkaline medium. The optimized electrode only requires a small overpotential of 233 mV to reach the current density of 10 mA cm-2, and the catalytic activity of the electrode can surpass several related electrodes reported in the literature. In addition, the long-term stability of the Fe2.3%-Ni3S2/NF electrode showed no significant attenuation after 12 h of testing at a current density of 50 mA cm-2. The introduction of Fe ions could modulate the electrical conductivity and morphology of the Ni3S2 structure and thus provide a high electrochemically active area, fast reaction sites, and charge transfer rate for OER activity.

Developing new electrocatalysts for oxygen evolution reaction via high throughput experiments and artificial intelligence

The development of non-noble metal electrocatalysts for the Oxygen Evolution Reaction (OER) is advancing towards the use of multi-element materials. To reveal the complex correlations of multi-element OER electrocatalysts, we developed an iterative workflow combining high-throughput experiments and AI-generated content (AIGC) processes. An increased number of 909 (compared to 145 in previous literature) universal descriptors for inorganic materials science were constructed and used as Artificial Neural Network (ANN) input. A large number of statistical ensembles with each ANN individual ensemble having a reduced number of descriptors were integrated with a new Hierarchical Neural Network (HNN) algorithm. This algorithm addresses the longstanding challenge of balancing overwhelming descriptor numbers with insufficient datasets in traditional ANN approaches to materials science problems. As a result, the combination of AIGC and experimental validation significantly enhanced prediction accuracy, increase the R2 values from 0.7 to 0.98 for Tafel slopes.

High-Dimensional Nb2O5 with NbO6 Octahedra for Efficient Electrocatalytic Upgrading of Methanol to Formate.

Facilitating the selective electrochemical oxidation of methanol into value-added formate is essential for electrochemical refining. Here we propose a high-dimensional Nb2O5 on Ni foam (Nb2O5-HD@NF) composite as anode for methanol oxidation reaction (MOR) for efficient production of formate. In an electrolyte containing 3 M methanol aqueous solution, the Nb2O5-HD@NF anode requires only 240 mV overpotential to deliver an industrial-level current density of 100 mA cm-2 with a formate Faraday efficiency of 100%. In situ Raman and electrochemical kinetic analyses reveal that the origin of the excellent activity in 3 M methanol electrolyte can be ascribed to the NbO6 octahedra as active sites and the Lewis acid sites on the surface of Nb2O5-HD. This work may pave a way for the design of non-noble metal electrocatalysts with surface acidity engineering for the effective electrocatalytic upgrading of biomass molecules.

(Invited) Electrolyte Engineering for Disruptive Cost Reduction of Electrolyzer: Hydrogen Generation from Dense Carbonate Buffer Solution

Water electrolysis using renewable electricity is a key process for generating green hydrogen, a crucial element in the pursuit of a sustainable society. To make substantial strides in lowering the cost of green hydrogen, it is imperative to address not only the expense of the electricity involved but also the cost associated with the electrolyzer itself [1]. The current challenge lies in the materials chosen for electrolyzers operating under extreme acidic or alkaline conditions, which necessitate the use of costly corrosion-resistant components. A viable solution involves considering non-extreme pH water as an electrolyte, allowing for the utilization of affordable and readily available materials, such as iron or stainless steel, in key electrolyzer components like the frame or bipolar plate [2]. Despite the reported inferior performance of non-extreme pH electrolysis compared to extreme pH conditions, primarily due to inevitable pH shifts (resulting in concentration overpotential) and elevated solution resistance, advancements in technology and research hold the potential to overcome these challenges.Our research group has been actively engaged in the exploration of electrolyte engineering, a concept centered on optimizing the diffusion flux of buffer ions to mitigate the previously mentioned challenges in non-extreme pH conditions [3,4]. Our approach involves leveraging a dense buffer solution to maximize the flux of buffer ions, resulting in a significant reduction in concentration overpotential. This strategy becomes even more impactful when the operating temperature is elevated to the commercially viable range of 80-100 °C [5]. The synergistic effect of employing a dense buffer solution, combined with elevated temperatures, proves to be a promising avenue for advancing electrolyte engineering and optimizing the performance of electrolysis systems in non-extreme pH conditions. In this presentation, we will delve into our discoveries concerning non-noble metal electrocatalysts, specifically focusing on their efficacy in both the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER).Our research has led us to identify transition metal-based electrocatalysts that demonstrate exceptional efficiency in catalyzing OER within a carbonate buffer electrolyte at near-neutral pH [6]. Among the diverse materials we explored, the iron-nickel composite, coupled with copper or gold on electrochemically activated Ni (ECA-Ni) substrates [7], stands out as a superior performance. Notably, these electrodes exhibited a remarkable OER catalysis rate of 1 A cm−2 and an overpotential of approximately 330 mV, becoming competitive with highly alkaline counterpart.Next, our research has uncovered noteworthy electrocatalysts based on copper and molybdenum, demonstrating exceptional efficiency in catalyzing the hydrogen evolution reaction (HER) within a carbonate buffer electrolyte at pH 10.5 [8]. The most promising sample achieved a current density of 1 A cm−2 at an overpotential of approximately 0.2 V, a performance comparable to previously reported HER results in highly alkaline conditions. Detailed characterization of these electrocatalysts unveiled that the addition of copper resulted in a rougher surface structure, contributing to the largest double-layer capacitance. These characteristics are indicative of an enlarged active surface area, which is pivotal for enhanced catalytic activity. Furthermore, the introduction of copper element correlated with a decreased apparent Tafel slope, suggesting a tailored nature of the active sites. These insights not only shed light on the structural modifications induced by copper but also underscore its role in optimizing the electrocatalytic performance.Finally, we integrated the previously developed HER and OER catalysts with a carefully selected polyether sulfone (PES) diaphragm [8]. This strategic combination resulted in a notable enhancement of overall cell performance within a 3.0 mol kg− 1 K-carbonate solution at pH 10.5 and a temperature of 353 K. The resultant cell performance, factoring in the series resistance, achieved a 1 A cm− 2 at a voltage of approximately 2.0 V. This achievement stands competitively against the top-class commercial alkaline electrolyzers. These findings not only highlight the feasibility of non-extreme pH electrochemical electrolyzers in industrial applications but also underscore the potential for further advancements and optimizations. The demonstrated success serves as a compelling indicator of the viability of our approach and opens avenues for refining non-extreme pH electrolysis for even greater efficiency and applicability in industrial settings.Reference[1] M. Chatenet, et al., Chem. Soc. Rev. 2022, 51, 4583.[2] M. Pourbaix, “Atlas of Electrochemical Equilibria in Aqueous solutions”, 1974.[3] T. Shinagawa and K. Takanabe, ChemSusChem 2017, 10, 1318.[4] T. Shinagawa et al., ChemCatChem 2019, 11, 5961.[5] T. Naito, et al., ChemSusChem 2022, 8, e202102294.[6] T. Nishimoto, et al., ChemSusChem 2022, e202201808.[7] T. Shinagawa, et al., Angew. Chem. Int. Ed. 2017, 56, 5061.[8] T. Nishimoto, et al., ACS Catal. 2023, 13, 14725.

Exploring the Phase Transformation of Tri-Metallic Prussian Blue Analogue Pre-Catalyst for Improved Oxygen Evolution Reaction

The development of non-noble metal electrocatalyst with high-efficiency and clear underlying of the related reaction mechanism towards the sluggish oxygen evolution reaction (OER) is critical for large-scale hydrogen production. In this study, tri-metallic Prussian blue analogue (PBA) of FeCoNi-PBA was synthesized using a facile and low-energy consumption co-precipitation method. The FeCoNi-PBA was found to be etched by the high-pH 1 M KOH electrolyte such that under anodic applied potential during electrolysis the formation of metal (oxy)hydroxide is accelerated. Operando Raman and post-mortem characterizations reveal that the applied anodic potential promotes the phase transformation so that the PBA undergoes self-reconstruction to form metal (oxy)hydroxide embedded in a carbon matrix with fully exposed active sites. The metal (oxy)hydroxide serves as the real active sites while the carbon matrix is believed to enhance the conductivity and hydrophilicity, which facilitates the electron transfer and electrolyte diffusion to improve the OER performance. In alkaline media, FeCoNi-PBA demonstrates excellent OER performance with a low overpotential of 236 mV at 10 mA cm−2, small Tafel slope of 43.8 mV dec-1, and long-term durability.

Electrodeposition of Non-Noble High-Entropy Alloys for Effective Hydrogen Evolution Electrocatalysts

As society works towards reducing its carbon footprint, various sectors such as energy, steelmaking and fertilizer production have begun to look increasingly towards decarbonization. Hydrogen production through electrolysis, when linked to renewables (solar, wind), provides a promising low-emission alternative as an energy carrier and chemical feedstock. With the decreasing cost of said renewables, greater focus is now on the capital cost of the electrolyser, and particularly the membrane/electrode structures. Conventional Proton Exchange Membrane (PEM) electrolysers rely on the use of electrocatalysts made with expensive noble metals such as platinum, ruthenium, and palladium [1]. Anion Exchange Membrane (AEM) electrolysers present an effective means of alkaline water splitting with low carbon emissions and can effectively utilize non-noble metal electrocatalysts for the Hydrogen Evolution Reaction (HER). A novel class of materials, High-Entropy Alloys (HEAs), made of non-noble metals or with reduced noble metal content have shown great promise as active electrocatalytic materials [2]. HEAs are typically defined as metal alloys made of five or more constituent elements each comprising at least 5% of the total material [3]. Having such a large number of principal alloying elements can lead to enhanced phase stability due to an increased configurational entropy, have unique chemical clustering, and can help prevent degradation of the material in harsh environments [2]. Additionally, the large lattice parameter mismatch between constituent elements can result in a high degree of strain which can help shift electronic states in a way that is favourable to hydrogen electrocatalysis [4]. These properties along with the so called “cocktail effect,” whereby combining multiple elements can result in unexpected synergistic interactions, makes HEAs uniquely suited to electrocatalytic applications [5].In this work, we investigate the electrocatalytic performance of electrodeposited FeNiCoMoW HEAs. The goal is to combine three hyper-d transition metals with two hypo-d transition metals to alter the electronic structure and improve electrocatalytic performance. Using chronoamperometric measurements, the Tafel slopes for FeNiCoMoW HEAs electrodeposited at pH 5, 6 and 7 were determined, with the pH 5 HEA demonstrating the smallest average Tafel slope of approximately 83 mV/dec. Compared to some electrodeposited binary alloys reported on in the literature, this marks an improvement and may be the result of unexpected interactions within the compositionally complex alloy. In the FeNiCoMoW HEA, the magnitude of the Tafel slope increased in tandem with the electrochemically active surface area (ECSA) as determined by Cyclic Voltammetry (CV) which suggests that the composition may be more important for improving performance. As the pH of the electrodeposition solution increased, the amount of cobalt in the as-deposited HEA decreased while the amounts of molybdenum and tungsten remained constant. The composition of nickel and iron appeared to vary inversely, reaching a maximum and minimum respectively at pH 6. From these results it seems that maximizing cobalt content and minimizing nickel content could potentially help to improve HER performance in the FeNiCoMoW system.

(Invited) Efficient Ternary Nicuw Hydrogen Oxidation Catalysts for Anion Exchange Membrane Fuel Cells

Anion exchange membrane fuel cells (AEMFCs) offer prospective approaches to replace proton exchange membrane fuel cells via cost-effective catalysts and membranes. While significant progress has been made in efficient nonnoble electrocatalysts for oxygen reduction reaction in alkaline media, the hydrogen oxidation reaction (HOR) in the alkaline condition still relies on high platinum loadings to compensate for its sluggish kinetics. Therefore, developing efficient non-noble metal electrocatalysts with Pt-like HOR performances in alkaline electrolytes is highly desired but a great challenge.The hydrogen binding energy (HBE) has been identified as the primary descriptor for the HOR. Additionally, an unfavorable hydroxide binding energy (OHBE) is considered the rate-determining step in the Volmer reaction to generate water. Therefore, an ideal catalyst for HOR should achieve a balance between HBE and OHBE. However, despite being a promising non-noble metal, nickel exhibits excessively high HBE and lacks active sites for hydroxide adsorption, which hinders its further application in the real fuel cell.In this work, NiW was successfully deposited onto Cu to form a ternary Ni-Cu-W alloy catalyst by a chemical reduction method. Through XPS spectra, we found the charge transfer from Ni to W to give Ni a higher valence state, contributing to a weakened hydrogen binding energy. Electrochemical measurements observed Ni-Cu-W exhibit an kinetic activity with 117.9 mA/mgNi at η= 50 mV, which is the highest among the reported platinum group metal-free catalysts. Ni-Cu-W alloy showcased robust stability, with no activity degradation during an accelerated long-term durability test between a low overpotential (-0.1 ~ 0.1 V, vs RHE) with 10,000 cyclic voltammetry scans and only a 5.7% activity loss at η= 50 mV when applying more larger overpotential (-0.1 ~ 0.2 V) with the same cycles. When assembled with this catalyst as anode and Pt/C as cathode, it delivered a peak power density of 289 mW/cm2. Both experimental and theoretical studies were conducted to gain insights into the catalyst's enhanced performance. Our findings revealed that the incorporation of Cu into the catalyst significantly weakened the adsorption of hydrogen species, while simultaneously lowering the energy barrier required for the absorption of hydroxide ions. These key observations might shed light on the underlying mechanisms responsible for the catalyst's improved activity and stability.

Nb-MXene as promising material for electrocatalysis in energy conversion (OER/ORR) and storage

Low-cost non-noble metal electrocatalysts are currently the focus of research and development for energy conversion and storage devices. MXenes, the newest class of two-dimensional materials, have high surface area, nanometer layer thickness, hydrophilicity and high electrical conductivity that favor their performance for electrocatalytic reactions. Herein, niobium carbide MXene (Nb-MXene) was obtained from its MAX phase by chemical synthesis and characterized regarding its morphology, structure and electrochemical activity for oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) as well as for charge storage in different electrolytic media. The results demonstrate the good performance of Nb-MXene for storing charge (104 F g−1 at 5 mV s−1) that increased remarkably with continuous cycling in an acidic medium. Current density for oxygen evolution of ∼32.5 mA cm−2 was reached in alkaline medium. The oxygen reduction reaction in the same media was observed to proceed via 2e− mechanism with a Tafel slope of 114 mV dec−1. Therefore, Nb-MXene presents characteristics and performance of a promising material for electrocatalytic reactions.

Recent progress and strategies of non-noble metal electrocatalysts based on MoS2/MOF for the hydrogen evolution reaction in water electrolysis: an overview

Recent progress and strategies of non-noble metal electrocatalysts based on MoS₂/MOF for the hydrogen evolution reaction in water electrolysis: an overview

Single atom catalyst induced by redox reaction between iron ion and aniline monomer

The effective design of a low-cost, efficient, and stable non-noble metal electrocatalyst to substitute the noble metal electrocatalyst for oxygen reduction reaction is highly significant. Even though atomically dispersed metal catalyst shows excellent catalytic activity with maximized atom efficiency, the challenge often lies in achieving uniform distribution for single-atom catalysts owing to their tendency to aggregate. In this work, we present a sequential method that involves the reduction of iron (Fe) mediated by aniline (anchored on support), followed by pyrolysis to fabricate the Fe-Nx moieties and achieve the high density of single atom active sites. The resulting Fe SA 900 catalyst exhibited a half-wave potential of 0.84 V vs. reversible hydrogen electrode (RHE) for oxygen reduction reaction and outstanding stability in alkaline condition. Using various analysis techniques and electrochemical analysis, we demonstrated that the electrocatalytic activity of the catalyst arises from Fe single atom. To validate the practical applicability of Fe-N-C catalysts, we conducted an anion exchange membrane fuel cell (AEMFC) test, which demonstrated a high performance of 212 mW cm−2 at maximum power density. This study proves that the effectiveness of a sequential strategy adopting redox reaction and following pyrolysis for precise synthesis of a single atom Fe catalyst.

Cation-vacancy-rich NiFe2O4 nanoparticles embedded in Ni3Se2 nanosheets as an advanced catalyst for oxygen evolution reaction

Developing efficient and economically viable approaches to produce non-noble metal electrocatalysts with high performance is crucial for anion exchange membrane water electrolyzers. Here, we present a novel and mild two-step method to producing highly active and stability NiFe2O4/Ni3Se2 electrocatalyst by utilizing the dissolution/redeposition effect. Notably, the NiFe2O4 nanoparticles (∼10 nm) wrapped by Ni3Se2 nanosheets creating plentiful heterostructures and strong coupling forces to realize high-efficient alkaline water electrocatalysis. Therefore, the NiFe2O4/Ni3Se2 electrocatalyst delivers current densities of 1000 mA cm−2 under overpotentials of 379 mV for alkaline oxygen evolution and operates over 1200 h across a range of current densities from 50 to 1000 mA cm−2. An anion exchange membrane water electrolyzers with NiFe2O4/Ni3Se2 electrocatalyst exhibits performance (1.85 V @ 0.5 A cm−2, 2.08 @ 1.0 A cm−2) superior to that of the benchmark device at room temperature, and robust stability under industrial conditions. Experimental results and theoretical investigations demonstrate that the special encapsulation structure effectively mitigated catalyst migration and modulated the adsorption of O-containing intermediates. This work provides a rational synthesis strategy and provides useful guidelines to facilely fabricate oxygen evolution reaction electrocatalyst with high performance for an industrial water electrolyzer.

One-step electrodeposition synthesis of NiFePS on carbon cloth as self-supported electrodes for electrochemical overall water splitting

Electrocatalytic water splitting (EWS) for hydrogen production is considered an ideal strategy for utilizing renewable energy, reducing fossil fuel consumption, and addressing environmental pollution issues. Traditional noble metal electrocatalysts have excellent performance, but their cost is high. Developing efficient, stable, and relatively inexpensive dual functional electrocatalysts is crucial for promoting large-scale EWS hydrogen production processes. Herein, a simple one-step electrodeposition method was used to grow nickel–iron phosphorus-sulfides (NiFePS) on the surface of hydrophilic treated carbon cloth (CC). The resultant NiFePS/CC with a phosphorus to sulfur ratio of 1:4 exhibited the best electrocatalytic performance, requiring only −91 mV and 216 mV overpotentials to generate the current densities of 10 mA·cm−2 in hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively. When it was used as a bifunctional electrocatalyst to overall water splitting (OWS), a voltage of 1.536 V can generate a current density of 10 mA·cm−2. The excellent electrocatalytic performance can be ascribed to two factors: 1) the CC with excellent conductivity serves as a growth substrate, reducing the impedance of charge transfer from the electrode to the electrolyte and accelerating the electron transfer rate; 2) The large number of ultra-thin nanosheets formed on the surface of the catalyst increase the electrochemical specific surface area, expose more reaction sites, and thus improve the electrocatalytic reaction performance. This work provides a new approach for designing efficient non-noble metal electrocatalysts for water splitting.

In-situ growth of MoSe2 on N-doped Ti3C2Tx for electrocatalytic hydrogen evolution in alkaline media

Abstract Serious environmental contamination and the energy crisis have heightened public desire for new renewable energy sources. Because of its high energy content and non-polluting qualities, hydrogen energy has emerged as a viable alternative to fossil fuels. Currently, high-purity hydrogen is typically produced through water electrolysis. The sensible use of electrocatalysts in this process can significantly minimize power usage in the electrolysis of water, which is of great significance to industrial production. However, the electrocatalyst that is inexpensive, has abundant reserves and performs well has yet to be discovered, severely restricting the promotion and application of hydrogen energy. In this paper, a MoSe2/N-doped Ti3C2TX heterostructure with notable electrocatalytic hydrogen evolution activity in an alkaline environment was fabricated via nitrogen doping and in-situ growth of molybdenum selenide. When the current density is 10 mA·cm-2, its overpotential and Tafel slope are 321.87 mV and 139.97 mV·dec-1, respectively. This work serves as a valuable experimental reference for the development of non-noble metal electrocatalysts based on two-dimensional materials.

N, P-doped NiCo2S4 nanospheres with excellent hydrophilicity for efficient oxygen evolution reaction

The rational design of a robust hydrophilic electrocatalyst is essential for enhancing its oxygen evolution reaction(OER). In this work, a nanosphere catalyst (NiCo2S4) composed of 2D-nanosheets was prepared. Interestingly, The hierarchically porous hydrangea-like N,P-NiCo2S4 structure was formed through the doping of nonmetal elements N and P. With the introduction of N and P, the electronic structure of Ni and Co can be optimized and the charge transfer resistance of NiCo2S4 can be reduced, thus improving the kinetics of OER. More importantly, N and P doping increased the hydrophilicity of NiCo2S4, which may have accelerated the surface reconstruction of NiCo2S4, resulting in the generation of truly active sites. Overall, this work not only optimised the electronic structure of NiCo2S4, but also improved its hydrophilicity through the synergistic interaction between the nonmetal elements N and P, which provided ideas for the development of advanced non-noble metal electrocatalysts.