Promoting electrocatalytic overall water splitting by sulfur incorporation into CoFe-(oxy)hydroxide

Solar-Powered AEM Electrolyzer via PGM-Free (Oxy)hydroxide Anode with Solar to Hydrogen Conversion Efficiency of 12.44

Water electrolyzers powered by renewable energy are emerging as clean and sustainable technology for producing hydrogen without carbon emissions. Specifically, anion exchange membrane (AEM) electrolyzers utilizing non-platinum group metal (non-PGM) catalysts have garnered attention as a cost-effective method for hydrogen production, especially when integrated with solar cells. Nonetheless, the progress of such integrated systems is hindered by inadequate water electrolysis efficiency, primarily caused by poor oxygen evolution reaction (OER) electrodes. To address this issue, a NiFeCo─OOH has developed as an OER electrocatalyst and successfully demonstrated its efficacy in an AEM electrolyzer, which is powered by renewable electricity and integrated with a silicon solar cell.

FeNi2 S4 -A Potent Bifunctional Efficient Electrocatalyst for the Overall Electrochemical Water Splitting in Alkaline Electrolyte

For a carbon-neutral society, the production of hydrogen as a clean fuel through water electrolysis is currently of great interest. Since water electrolysis is a laborious energetic reaction, it requires high energy to maintain efficient and sustainable production of hydrogen. Catalytic electrodes can reduce the required energy and minimize production costs. In this context, herein, a bifunctional electrocatalyst made from iron nickel sulfide (FeNi2 S4 [FNS]) for the overall electrochemical water splitting is introduced. Compared to Fe2 NiO4 (FNO), FNS shows a significantly improved performance toward both OER and HER in alkaline electrolytes. At the same time, the FNS electrode exhibits high activity toward the overall electrochemical water splitting, achieving a current density of 10 mA cm-2 at 1.63 V, which is favourable compared to previously published nonprecious electrocatalysts for overall water splitting. The long-term chronopotentiometry test reveals an activation followed by a subsequent stable overall cell potential at around 2.12 V for 20 h at 100 mA cm-2 .

Synthesis and water splitting performance of FeCoNbS bifunctional electrocatalyst

Transition metal (TM) sulfides are promising catalysts for water splitting in alkaline media due to their high intrinsic activities and similar TM-S electronic structure with hydrogenase. In this work, the nanoporous FeCoNbS electrocatalyst with nanosheet morphology is synthesized through dealloying AlFeCoNb alloy followed by the steam sulphurization. The introduction of S element improves the electronic structure, further increases the active sites, regulates the mass transfer and enhances the intrinsic activity. The Nb introduction improves the electron transfer ability of the catalyst. The synergistic effect of Fe, Co and Nb improves the intrinsic activity of the active site. The FeCoNbS catalyst exhibits good catalytic performance for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in alkaline solution. The overpotentials at 10 mA cm^-2 of HER and OER are 83 and 241 mV, respectively. The Tafel slopes of HER and OER are 101.2 and 35.5 mV dec^-1, respectively. The FeCoNbS can serve as overall water splitting electrode with the decomposition voltage of 1.61 V at 10 mA cm^-2.

Plasma-assisted synthesis of hierarchical defect N-doped iron–cobalt sulfide@Co foam as an efficient bifunctional electrocatalyst for overall water splitting

N-doped CoFeS was synthesized via an ion exchange method to prepare a precursor, followed by sulphidation and plasma-assisted engraving in nitrogen gas.

Hollow CoFe-based hybrid composites derived from unique S-modulated coordinated transition bimetal complexes for efficient oxygen evolution from water splitting under alkaline conditions

The oxygen evolution reaction (OER) is an important reaction in water splitting. However, the high cost and slow-rate catalysts hinder commercial applications. Although an important process for manufacturing of hollow structures, it is difficult to construct complicated hollow structures with an excellent and regulable shape for multi-component materials. In this study, we demonstrate that sulfur-Co,Fe bimetallic nitrogen carbon hollow composite hybrids (x-S-CoFe@NC) can be synthesized by regulating the amount of sulfur and using the hydrothermal method. For OER, 32-S-CoFe@NC exhibits excellent electrocatalytic activity with a low overpotential of 232 mV, which is higher than those of 0-S-CoFe@NC (270 mV), 23-S-CoFe@NC (247 mV), and RuO₂ (243 mV) catalysts at 10 mA cm^-2. In addition, with air as the cathode, a rechargeable Zn-air battery with outstanding long-life cycling stability for 80 hours based on 32-CoFe@NC + Pt/C is proposed. The advanced technique described here supplies a new route for preparing hollow transition bimetal carbon hybrids with an adjustable composite arrangement for electrocatalysis and water splitting.