Non-precious Metal Electrocatalysts Research Articles

Construction of core-shell NiFe LDH/Co(OH)F amorphous/crystalline heterostructure for synergistically enhanced electrocatalytic water oxidation

The development of high performance non-precious transition metal electrocatalysts for the oxygen evolution reaction (OER) is essential for the practical application of electrocatalytic water splitting. A promising strategy to prepare highly efficient and stable electrocatalysts for the OER can be achieved by constructing heterointerfaces between the amorphous and crystalline phases. Herein, a novel three-dimensional (3D) core-shell structured NiFe-LDH/Co(OH)F electrocatalyst on nickel foam (NF) with an amorphous/crystalline interface was achieved by growing 2D amorphous NiFe LDH nanosheets onto 1D crystalline Co(OH)F nanorod arrays using a simple two-step hydrothermal method. The resulting NiFe LDH/Co(OH)F/NF electrode exhibits outstanding electrochemical OER performance with an overpotential of 202 and 260mV at the current density of 10 and 100mAcm-2, a Tafel slope of 44.06mV dec-1, and an ultra-high stability over 100h at 300mAcm-2 without obvious degradation in 1M KOH. This research affords a new way to construct high-performance 3D hierarchical non-noble metal electrocatalysts for OER.

Ionic liquid modifying conductivity and hydrophobicity of B4C for enhanced electrosynthesis of H2O2

Electrosynthesis of hydrogen peroxide (H2O2) via two-electron oxygen reduction reaction (2e− ORR) is an attractive energy-efficient and decentralized alternative to the conventional anthraquinone process. However, designing non-precious metal catalysts with high activity, selectivity and stability is a great challenge. Here, we report a facile and effective approach to improve the catalytic performance of commercial boron carbide (B4C) by loading ionic liquid (IL), which exploits the complementary properties of high electrical conductivity and hydrophobicity of IL. The B4C catalyst with optimal IL loading possesses the highest conductivity and O2 adsorption, exhibiting high H2O2 selectivity in both neutral (∼96 %) and alkaline (∼93 %) electrolyte, which are nearly ∼34 % and ∼19 % higher than pristine B4C, respectively. Moreover, its production rate is ∼1.5 times that of pristine B4C at 130 mA cm−2 current density, resulting in a high concentration of H2O2 (5.93 wt%) produced in flow-cell reactor. The long-term cycle test demonstrates the desirable stability of IL@B4C/GDE, which is attributed to the high hydrophobicity and tight bonding between IL@B4C and the substrate, giving a strong flood-proof capability at the three-phase interface and avoiding rapid flooding by the electrolyte. This work provides new insights into designing non-precious metal electrocatalysts for efficient electrosynthesis of H2O2, emphasizing the role of IL in interface engineering.

Leveraging interlocking structural defects of g-C3N4/CNT networks: Toward enhanced oxygen reduction activity of the cobalt-based electrocatalyst

Carbon-based transition-metal electrocatalysts are regarded as promising candidates for catalyzing oxygen reduction reaction (ORR), yet their electrocatalytic ORR performances are greatly limited by active sites utilization caused by the metal aggregation and pore collapse under high temperature. This study rationally designed a cobalt-based ORR catalyst supported on a g-C3N4/carbon nanotube (CNT) network as a cost-effective alternative of platinum-based catalysts. CNT were embedded into the lamellar precursor of melamine and cyanuric acid, and a synergistic effect between CNT and precursor was realized to regulate the density and activity of active sites. The polycondensation of precursors led to the formation of an "interlocking" structure of CNT supports with abundant exposed defects, allowing for effectively anchoring cobalt ions to generate Co-Nx sites. Meanwhile, partial Co ions underwent reconstruction and transportation to form Co nanoparticles and extended the disruptive CNT structure, exposing more interfacial defects to enhance the ORR catalytic properties. The prepared Co@g-C3N4/CNT catalyst demonstrated impressive ORR activity comparable to commercial Pt/C catalyst, showing superior stability. This research offers a promising approach for engineering interfacial defects to synthesize high-performance non-precious metal electrocatalysts for energy conversion applications.

“Nanoregion” effect of ionic liquid mixture system for preparing highly active porous electrocatalytic hydrogen production materials

The development of porous electrocatalytic materials with high activity and large specific surface area is the key to realizing efficient hydrogen production by water electrolysis. In this paper, a universial strategy for preparing porous non-precious metal electrocatalysts with high effective surface area is provided based on the “nanoregion” formed by ionic liquid mixture system, and the feasibility is verified by constructing a porous NiCo@NC based electrocatalyst. The microstructure, surface composition, specific surface area and electrochemical properties of the porous electrocatalyst are investigated systematically. Compared with the traditional hydrothermal synthesis, the “nanoregion” effect can give the NiCo@NC electrocatalyst rich pore structure and good hydrophilicity, thus effectively improve the effective surface area available for the electrochemical reaction. As a result, the overpotential for HER on NiCo@NC-500 prepared in the ionic liquid mixing system is 113 mV lower than that on NiCo@NC-500-w prepared by common hydrothermal process, and the Tafel slope decreases by 37 mV dec−1 (33.9 %), further verifying the effectiveness of this simple and green strategy to develop porous non-precious metal electrocatalysts for hydrogen production by the “nanoregion” effect of ionic liquid mixture system.

Heterointerfacial engineering of N,P-doped carbon nanosheets supported Co/Co2P nanoparticles for boosting oxygen reduction and oxygen evolution reactions towards rechargeable Zn-air battery

Transition metal phosphides (TMPs) with high electrocatalytic activity for the oxygen evolution reaction (OER) are reckoned as a substitution of precious group metals catalysts in rechargeable Zn-air battery. In this work, Co/Co2P heterojunction nanoparticles supported N,P-doped carbon nanosheets (Co/Co2P@NPCNS) were designed and prepared via a facile one-step molten salt-assisted pyrolysis process. Density function theory calculations reveal that the heterogeneous interactions of Co/Co2P effectively enhance the bifunctional electrocatalytic activity for oxygen reduction reaction (ORR) and OER. The synergistic interaction between the Co/Co2P heterojunction nanoparticles with highly exposed active sites and excellent catalytic activity and the two-dimensional doped carbon nanosheets with high conductivity contributes to Co/Co2P@NPCNS exhibiting preeminent bifunctional ORR/OER activity and stability with a high half-wave potential for ORR (0.87 V), a low overpotential for OER (302 mV at 10 mA cm−2) and a low potential gap (0.66 V). The homemade rechargeable Zn-air battery performs high peak power density (187 mW cm−2) and exceptional endurance. This heterogeneous interface tactic of integrating TMPs with heteroatom-doped carbon materials may shed light on the research and development of non-precious metal electrocatalysts.

Ni-CoS2 nanoparticles loaded on 3D RGO for efficient electrochemical hydrogen and oxygen evolution reaction

The development of efficient non-precious metal electrocatalysts for electrochemical water splitting is still a huge challenge. In this study, we designed and synthesized an efficient electrocatalyst for Ni-doped cobalt sulfide supported on 3D RGO (Ni-CoS2/3D RGO) using a simple one-step solvent-thermal method. Ni doping adjusted the charge distribution on the surface of the material, significantly improved the catalytic activity, and then accelerated the reaction kinetics. The high specific surface area and high stability of 3D RGO greatly improved the intrinsic activity of the material, making Ni-CoS2/3D RGO exhibit superior catalytic activity in both electrochemical hydrogen evolution and oxygen evolution. We evaluated the morphology and properties of the catalysts through a series of characterization methods and electrochemical performance tests. When the current density is 10 mA cm−2, the HER overpotential of Ni-CoS2/3D RGO under acidic condition reaches 138 mV, and the Tafel slope is 61 mV dec−1. Under alkaline conditions, the OER overpotential reaches 286 mV, and the Tafel slope is only 48 mV dec−1. And the OWS overpotential of the catalyst is 1.41 V and 1.82 V under acidic and alkaline conditions, respectively, indicating that the catalyst has ideal water splitting performance. This work provides a new idea for the application of 3D reduced graphene oxide in electrochemical direction, and also provides a new strategy for the design and preparation of non-precious metal catalysts for the efficient electrochemical water splitting.

Enhanced Zinc-air battery performance and local electrochemical evaluation of atomically dispersed Co and Ni in S, N-codoped carbon nanofibers via scanning electrochemical microscopy

This study reports the successful synthesis of a novel electrocatalyst for oxygen reduction reactions (ORR), comprising S,N dual-doped carbon nanofibers with atomically dispersed Co/Ni species (denoted as Co,Ni-SAs/S,N-CNFs), leveraging electrostatic spinning to achieve a unique spatial architecture that maximizes both active site density and mass transport efficiency. Density functional theory (DFT) analysis identified the initial proton-electron transfer to adsorbed O2 as the rate-limiting step, with CoN3S1-NiN3S1 emerging as the pivotal active site structure catalyzing this critical reaction. The fabricated Co,Ni-SAs/S,N-CNFs electrocatalyst exhibited remarkable ORR performance, characterized by a high half-wave potential of 0.84 V and a low Tafel slope of 57.9 mV dec-1. To gain a comprehensive understanding of its catalytic behavior, a tailored temperature-controlled scanning electrochemical microscopy (SECM) was employed, enabling the mapping of reactivity distribution under simulated operating conditions while preserving structural integrity. Liquid zinc-air batteries (ZABs) with this electrocatalyst excelled, reaching 175 mW/cm2 power density and enduring 1240 cycles. The electrospun membrane catalyst enabled both button and flexible ZABs, adaptable to diverse environments. This study advances non-precious metal electrocatalyst design and offers insights for ZAB applications, fostering green energy prospects.

Construction of high-efficiency Fe-MnO@Fe electrocatalyst for methanol and ethanol oxidation in alkaline medium

Abstract Acquiring effective, durable and economical non-precious metal electrocatalysts is crucial for the widespread utilization of fuel cells. In this work, an iron/manganese oxide nanocomposite (Fe-MnO@Fe) is synthesized as a novel electrocatalyst by direct-current (DC) arc plasma technology integrating transition metal and transition metal oxide. The Fe-MnO@Fe catalyst demonstrates excellent catalytic performance. By modulating the percentage of transition metal and transition metal oxide in the composite, the largest current density values of methanol and ethanol oxidation of the composite reach 20.18 and 7.83 mA/cm2, respectively. In addition, the composite catalyst exhibits excellent stability and conductivity, and the catalyst greatly reduces the experimental cost relative to the noble metal catalysts, indicating that the composite is a potential fuel cell catalyst candidate and provides an innovative concept for creation non-precious metal catalysts.

Accelerated structural transformation of metal-organic frameworks via interfacial engineering for efficient oxygen evolution reaction

Most metal-organic frameworks (MOFs) undergo structural transformations during the oxygen evolution reaction (OER), prompting the development of more catalytically active metal oxyhydroxides. However, one of the biggest challenges still is managing the MOF reconstruction process. Here, we present an interface engineering strategy to encourage MOFs to structurally change into metal oxyhydroxides, which are more active in the OER process. By meticulous design, the NiSe/CoFc′ (CoFc-MOF, Fc′ = 1,1′-ferrocenecarboxylic acid) heterojunction was successfully constructed, exhibiting remarkable interface coupling effects. This characteristic not only facilitates efficient electron transfer from CoFc′ to NiSe, and accelerates the structural transformation process of CoFc′, but also activates more catalytic active sites. Compared to pure CoFc′, NiSe/CoFc′ exhibits enhanced structural transformation capability, occurring in a shorter time and at a lower voltage, with more catalytic sites being activated. Furthermore, the transformed NiSe/CoFc′ displays suprior catalytic activity with an overpotential of 227 mV at a current density of 100 mA cm−2, surpassing the single-component CoFc′. And the Faradaic efficiency of NiSe/CoFc′ is near to 99.6%. This approach offers a noval avenue for the levelheaded plan of non-precious metal electrocatalysts for water electrolysis, enabling the control of structural conversion through interface engineering.

Regulation of surface oxygen vacancy of Cu-CeO2/TiO2 heterostructures via fast Joule heating method for enhanced CO2 electrochemical reduction

Strict control of carbon emissions is crucial for expediting the achievement of carbon neutrality. However, the current CO2RR electrocatalytic exhibits numerous shortcomings that impede the enhancement of catalytic activity. Issues such as lengthy catalyst preparation times, and high levels of precious metal content. Additionally, the aggregation of ultrafine nanoparticles contributes to a rapid deterioration in catalytic performance. Herein, a Joule-heating method is efficiently utilized to synthesize heterostructures nano-catalysts for CO2 electroreduction on carbon cloth substrates. This method takes advantage of the thermoelectric coupling of the carbon cloth to achieve carbothermal reduction, while also regulating phase composition and introduction of oxygen vacancies. The Cu-CeO2/TiO2/CC catalyst synthesized in this method showed a current density in CO2 of −32 mA·cm−2 at −1.0 V (vs. RHE). Notably, this catalyst demonstrated high CO selectivity and Faraday efficiency (FECO) of up to 82.5 % at a low potential of −0.3 V (vs. RHE). Optimal electrochemical performance is achieved at a power of 40 W. The ultra-fast temperature change process prevented the agglomeration of catalyst particles and facilitated the construction of a stable heterogeneous interface with a high oxygen vacancy concentration. In conclusion, this study presents a promising approach, particularly for the rapid preparation of low-cost, highly selective non-precious metal electrocatalysts.

M (M=Mn, Fe, and Cu)-doped Ni3S2@Co9S8 grown on Ni foam with different heterostructures as catalysts for overall seawater splitting

The increasing global energy demand and the environmental impact of fossil fuels have prompted scientists to seek clean and renewable energy solutions. Hydrogen energy, known for its efficiency and environmental benefits, is considered an ideal choice. Given the limited availability of freshwater resources, this study uses abundant seawater as the feedstock for water electrolysis. Our research focuses on developing non-precious metal electrocatalysts to enhance the efficiency and economic viability of water electrolysis for hydrogen production. Using Ni3S2@Co9S8 as the base material, we regulate the catalytic performance by doping with transition metals such as Mn, Fe, and Cu. The Mn-Ni3S2@Co9S8/NF electrode exhibits excellent hydrogen evolution reaction (HER) (overpotential of 76 mV @10 mA cm−2) and oxygen evolution reaction (OER) (overpotential of 261 mV @10 mA cm−2) activity in seawater electrolytes, significantly reducing the overpotential requirements. Density Functional Theory (DFT) assessments reveal that Co9S8 possesses optimal gibbs free energy capabilities and Mn-Ni3S2 possesses more electron distribution, explaining its high catalytic efficiency. This study provides an in-depth analysis of the catalyst structure and performance, offering valuable insights for developing efficient and stable electrocatalysts for water electrolysis, thereby contributing to the sustainable development of the hydrogen economy and advancements in clean energy technology.

Zr and Mo doping to modulate the electronic structure of Ni3S2 for OER electrocatalysis

To enter the era of a clean and sustainable hydrogen economy, it is crucial to first discover non-precious metal electrocatalysts that can be used for oxygen evolution reaction (OER) in electrochemical water splitting. In this work, highly active and durable Zr and Mo co-doped Ni3S2 catalyst (ZrMo–Ni3S2/NF) loaded on Ni foams for OER in alkaline media were prepared using a simple one-step hydrothermal method. The resulting nanocomposites were characterized by various methods and evaluated for their electrocatalytic performance towards OER. The ZrMo–Ni3S2/NF nanocomposite exhibites excellent OER electrocatalytic activity with a low overpotential of 257 mV at a current density of 10 mA cm−2 as well as an excellent electrochemical stability, showing only a slight decay during the 70 h test period. The remarkable electrocatalytic performance of the ZrMo–Ni3S2/NF electrode is attributed to the synergistic strong electronic interaction between the co-doped Zr and Mo. This work not only demonstrates a highly electrocatalytic active OER catalyst for water splitting, but also provides a new perspective on the development of highly active OER catalysts through doping strategies.

(Digital Presentation) Improvement of Oxygen Reduction Activity on Ti Oxide-Based Electrocatalyst

For widespread utilization of fuel cell system in the future, we have focused on non-precious metal electrocatalyst against high cost of system. Especially, we have studied and reported group 4 and 5 metal oxide-based electrocatalyst as non-platinum catalysts for the oxygen reduction reaction (ORR) because of low-cost, abundant reserves, and high stability in acidic electrolytes [1-2]. We have found excellent ORR activity of Zr oxide-based electrocatalysts prepared from pyrazinecarboxylic acid as a precursor [3-4]. In the case of Ti oxide-based electrocatalysts, the sample prepared under low partial pressure of oxygen with the heat treatment shows high ORR activity when it uses nitrogen-containing porphyrin cyclic organic Ti complexes (TiOTPPz) with multi-walled carbon nanotubes (MWCNTs) as a precursor. However, the heat treatment conditions have not widely investigated yet [5]. In this study, we have investigated to improve ORR activity of Ti oxide-based electrocatalyst prepared from TiOTPPz by varying the oxygen concentration during heat treatment.Oxytitanium tetrapyrazinoporphyrazine (TiOTPPz, [TiOC24H8N16]), a porphyrin cyclic nitrogen-containing organic Ti complex, was used as a starting material. 0.39 g of TiOTPPz and 0.26 g of MWCNT were mixed and treated in a dry ball mill for 1 h to obtain the precursor. The precursor was heated up to 900 oC in an Ar atmosphere and then annealed at 900 oC for 3 h in a low-oxygen atmosphere to obtain a catalyst with precipitated carbon and Ti oxide dispersed on the MWCNTs. The conditions of the hypoxic atmosphere were 2 %H2 + n %O2 / inert gas, with n = 0.05, 0.1, 0.5, 1.0, and 2.0. Catalysts are denoted by TiCNO_(O2 concentration during heat treatment). The catalyst powder was dispersed into 1-propanol with Nafion solution to prepare a catalyst ink. The ink was dropped on a glassy carbon rod, and dried for an hour to use as a working electrode in electrochemical measurement.Electrochemical measurements were performed in 0.5 mol dm-3 H2SO4 at 30 oC with a conventional 3-electrode cell. A reversible hydrogen electrode (RHE) and a glassy carbon plate were used as used as a reference and counter electrode, respectively. Slow scan voltammetry (SSV) was performed at a scan rate of 5 mV s-1 from 0.2 V to 1.2 V vs. RHE under O2 and N2. The ORR current (i ORR) was determined by calculating the difference between the current under O2 and N2.Figure 1 shows oxygen reduction activity of Ti oxide-based electrocatalyst. The vertical axis shows the |i ORR@0.8 V|. The |i ORR@0.8 V| was less than 100 mA gcat -1 at O2 concentrations of 0.05 and 0.1 %, and was greatest at 0.5 % at 413 mA gcat -1. The concentration of O2 further decreased with increasing O2 concentration, and was the smallest at 2.0%. It is suggested that the O2 concentration during heat treatment may have an optimum value around 0.5%.We have also analyzed the catalysts by the XRD before electrochemical measurements. According to XRD spectra, the presence of TiC0.3O0.7 was confirmed in all catalysts. In Ti-CNO_0.5 %, the most active catalyst, the diffraction peaks identified TiO2 rutile and TiO2 anatase were observed. In the case of Ti-CNO_1 and 2 %, the peak intensities of TiO2 anatase increased and the ORR activity decreased. This indicates that the degree of Ti oxidation can be controlled by the atmosphere during heat treatment.Acknowledgement: The authors thank for providing TiOTPPz from Dainichiseika Color & Chemicals Mfg. Co., Ltd.Reference[1] A. Ishihara, Y. Ohgi, K. Matsuzawa, S. Mitsushima, and K. Ota, Electrochim. Acta, 55, 8005 (2010).[2] A. Ishihara, S. Tominaka, S. Mitsushima, H. Imai, H. Imai, O. Sugino, and K. Ota, Curr. Opin. Electrochem., 21 , 234 (2020).[3] Y. Takeuchi, K. Matsuzawa, T. Nagai, K. Ikegami, Y. Kuroda, R. Monden and A. Ishihara, Bull. Chem. Soc. Jpn., 96, 175 (2023).[4] Y. Takeuchi, K. Matsuzawa, Y. Matsuoka, K. Watanabe, T. Nagai, R. Monden and A. Ishihara, Electrochemistry, (2023) in press[5] T. Hayashi, A. Ishihara, T. Nagai, M. Arao, H. Imai, Y. Kohno, K. Matsuzawa, S. Mitsushima and K. Ota, Electrochim. Acta, 209, 1 (2016). Figure 1

Boosting the Oxygen Reduction Performance of Fe–N–C Catalyst Using Zeolite as an Oxygen Reservoir

Non-precious metal electrocatalysts (such as Fe–N–C materials) for the oxygen (O2) reduction reaction demand a high catalyst loading in fuel cell devices to achieve workable performance. However, the extremely low solubility of O2 in water creates severe mass transport resistance in the thick catalyst layer of Fe–N–C catalysts. Here, we introduce silicalite-1 nanocrystals with hydrophobic cavities as sustainable O2 reservoirs to overcome the mass transport issue of Fe–N–C catalysts. The extra O2 supply to the adjacent catalysts significantly alleviated the negative effects of the severe mass transport resistance. The hybrid catalyst (Fe–N–C@silicalite-1) achieved a higher limiting current density than Fe–N–C in the half-cell test. In the H2–O2 and H2–air proton exchange membrane fuel cells, Fe–N–C@silicalite-1 exhibited a 16.3% and 20.2% increase in peak power density compared with Fe–N–C, respectively. The O2-concentrating additive provides an effective approach for improving the mass transport imposed by the low solubility of O2 in water.

CoFe phosphide conversion to heterojunction metal phosphide (CoFeP) electrocatalysts for water splitting

Many researchers have made efforts on designing and synthesizing catalytic active site as well as deciphering how exactly they catalyze the reaction to obtain electrocatalysts with superior water splitting activity. However, the development of high-performance dual-functional non-precious metal electrocatalysts for Hydrogen Evolution Reaction (HER) and Oxygen Evolution Reaction (OER) remains challenging. In this study, CoFe undergoes in a one-step phosphorylation reaction converted to Fe2P, CoP2 and Co2P, abbreviated as heterojunction metal phosphide (CoFeP). The Co/Fe ratio can be flexibly adjusted by controlling the content of Co in the synthesis process, which results in CoFeP with different morphologies. Benefiting from the porous structure and higher catalytic active sites, the Co-0.0032-FeP presents a lower overpotential of 127 mV and 266 mV for HER and OER of 10 mA cm−2 in a KOH solution, respectively. In addition, the low Tafel Slope and stable current density of Co-0.0032-FeP indicate fast kinetics and high stability in the HER.

Design and construction of 3D porous hierarchical structure Ni–Fe–Co bifunctional catalyst toward highly efficient overall water splitting

Developing high performance, cost-effective, non-precious metal electrocatalysts for overall water splitting (OWS) still remains a serious challenge. Heterostructures comprised of multiple metals possess significant potential to enhance OWS owing to the prominent synergistic effects between different components. Herein, we successfully fabricated NiFeCoPSO and Co(OH)2/NiFeSO structures with a three-dimensional (3D) porous hierarchical structure, using carbon cloth (CC) as a substrate. The innovative 3D hierarchical structure ensures that numerous active sites are extensively exposed, thus guaranteeing competent contact between the active reaction centers and the reactant. As a result, the obtained NiFeCoPSO displays outstanding hydrogen evolution reaction (HER) ability (102 mV for a current density of 10 mA cm−2), while the intermediate product Co(OH)2/NiFeSO exhibits excellent oxygen evolution reaction (OER) performance (231 mV for 10 mA cm−2). Furthermore, the dual electrode system assembled using NiFeCoPSO cathode and Co(OH)2/NiFeSO anode presents excellent overall water splitting (OWS) behavior (1.55 V for 10 mA cm−2). This research offers a cost-effective transition metal phosphide-sulfide electrocatalyst and its synthesis method for OWS.

Synergistically coupled CoMo/Fe2O3 electrocatalyst for highly efficient and stable overall water splitting

Constructing bifunctional non-precious metal electrocatalysts with advanced industrial value and excellent electrocatalytic performance to achieve efficient overall water splitting is important but difficult. Herein, a heterogeneous electrocatalyst comprising of CoMo alloys anchored Fe2O3 nanosheets was prepared by hydrothermal and electrodeposition methods. The strongly coupled interfaces between the CoMo alloys and Fe2O3 nanosheets promote charge redistribution, which could improve electron transfer efficiency and accelerate reaction kinetics, potentially optimizing reactant adsorption energy. Further density functional theory (DFT) calculations reveal that the construction of CoMo/Fe2O3/NF heterostructured catalyst facilitates to promote interfacial charge redistribution and enhance charge transfer capacity, thus boosting the catalytic performance. Benefiting from this, the optimal CoMo/Fe2O3/NF heterostructure demonstrates a minimal overpotential of 71 mV at 10 mA cm−2 for the HER and 266 mV at 50 mA cm−2 for the OER. Remarkably, the catalyst served as a bifunctional electrode for water splitting, resulting in a cell voltage down to 1.5 V at a current density of 10 mA cm−2. This research provides an effective way for the construction of non-precious iron oxides-based bifunctional electrocatalysts using alloy/metal oxide interfacial engineering strategy.

Preparation of sugarcane bagasse carbon-coated molybdenum phosphide nanocomposite electrocatalyst for hydrogen evolution reaction

The hydrogen evolution reaction (HER) based on electrochemical water decomposition is a promising method for producing clean and sustainable hydrogen energy. However, it is necessary to find high-activity, inexpensive, and durable non-precious metal-based electrocatalysts to realize HER. In this study, we prepared sugarcane bagasse carbon (SCBC) coated molybdenum phosphide nanocatalyst (MoP/SCBC) using a simple method and investigated the HER of the catalyst in acidic media. The MoP nanoparticles were uniformly coated on SCBC to form a unique structure, resulting in excellent electrocatalytic activity and stability of the MoP/SCBC catalyst in 0.5 M H2SO4 solution. The overpotential of the MoP/SCBC-900 catalyst was as low as 126 mV at 10 mA cm−2. The Tafel slope was 60.6 mV dec−1, and the Cdl was 18.83 mF cm−2, which outperformed most reported MoP-based HER catalysts. This study provides a more effective approach for developing high performance MoP based non-precious metal electrocatalysts derived from low-cost biomass.

Superhydrophilic cobalt-doped NiFe LDH graphite felt with enriched oxygen vacancy as an efficient oxygen evolution electrocatalyst in alkaline media

Efficient non-precious metal electrocatalysts are crucial for hydrogen production through water electrolysis. Combining a superhydrophilic electrocatalyst with oxygen vacancy and a conductive carbon matrix is significant for NiFe LDH-based oxygen evolution reaction (OER) applications. In this study, NiFe LDH nanoflowers and Co-doped NiFe LDH nanoneedles were synthesized on graphite felt through an in-situ self-assembly strategy. Further results have shown that doping Co into NiFe LDH nanoarrays significantly enhances the specific surface area and oxygen vacancy density, while the graphite felt serves as a conductive scaffold and prevents active sites detachment. Oxygen vacancies in Co3–Ni7Fe3 LDH/TGF adjust the electronic configuration, and superhydrophilicity promotes effective electrolyte diffusion. This synergy endows Co3–Ni7Fe3 LDH/TGF with excellent OER performance, lower overpotential of 252 mV (10 mA cm−2), a Tafel slope (63.13 mV), and stability at high current densities. This research provides a new perspective for utilizing non-precious metal catalysts on carbon substrates for hydrogen production.

Flexible tungsten disulfide superstructure engineering for efficient alkaline hydrogen evolution in anion exchange membrane water electrolysers

Anion exchange membrane (AEM) water electrolysis employing non-precious metal electrocatalysts is a promising strategy for achieving sustainable hydrogen production. However, it still suffers from many challenges, including sluggish alkaline hydrogen evolution reaction (HER) kinetics, insufficient activity and limited lifetime of non-precious metal electrocatalysts for ampere-level-current-density alkaline HER. Here, we report an efficient alkaline HER strategy at industrial-level current density wherein a flexible WS2 superstructure is designed to serve as the cathode catalyst for AEM water electrolysis. The superstructure features bond-free van der Waals interaction among the low Young’s modulus nanosheets to ensure excellent mechanical flexibility, as well as a stepped edge defect structure of nanosheets to realize high catalytic activity and a favorable reaction interface micro-environment. The unique flexible WS2 superstructure can effectively withstand the impact of high-density gas-liquid exchanges and facilitate mass transfer, endowing excellent long-term durability under industrial-scale current density. An AEM electrolyser containing this catalyst at the cathode exhibits a cell voltage of 1.70 V to deliver a constant catalytic current density of 1 A cm−2 over 1000 h with a negligible decay rate of 9.67 μV h−1.