Adjustable Ternary FeCoNi Nanohybrids for Enhanced Oxygen Evolution Reaction

Boosting Electrocatalytic Oxygen Evolution over Ce-Co9 S8 Core-Shell Nanoneedle Arrays by Electronic and Architectural Dual Engineering

An dual electronic and architectural engineering strategy is a good way to rationally design earth-abundant and highly efficient electrocatalysts of the oxygen evolution reaction (OER) for sustainable hydrogen-based energy devices. Here, a Ce-doped Co₉ S₈ core-shell nanoneedle array (Ce-Co₉ S₈ @CC) supported on a carbon cloth has been designed and developed to accelerate the sluggish kinetics of the OER. Profiting from valance alternative Ce doping, a fine core-shell structure and vertically aligned nanoneedle arrayed architecture, Ce-Co₉ S₈ @CC integrates modulated electronic structure, highly exposed active sites, and multidimensional mass diffusion channels; together, these afford a favorable catalyzed OER. Ce-Co₉ S₈ @CC exhibits remarkable performance in the OER in an alkaline medium, where the overpotential requires only 242 mV to deliver a current density of 10 mA cm^-2 for the OER; this is 70 mV superior to that of Ce-free Co₉ S₈ catalyst and other counterparts. Good stability and impressive selectivity (nearly 100 % Faradic efficiency) are also demonstrated. When integrated into a two-electrode OER//HER electrolyzer, the as-prepared Ce-Co₉ S₈ @CC displays a low operation potential of 1.54 V at 10 mA cm^-2 and long-term stability, thus demonstrating great potential for economical water electrolysis.

Nickel-Based Electrocatalysts for Water Electrolysis

Currently, hydrogen production is based on the reforming process, leading to the emission of pollutants; therefore, a substitute production method is imminently required. Water electrolysis is an ideal alternative for large-scale hydrogen production, as it does not produce any carbon-based pollutant byproducts. The production of green hydrogen from water electrolysis using intermittent sources (e.g., solar and eolic sources) would facilitate clean energy storage. However, the electrocatalysts currently required for water electrolysis are noble metals, making this potential option expensive and inaccessible for industrial applications. Therefore, there is a need to develop electrocatalysts based on earth-abundant and low-cost metals. Nickel-based electrocatalysts are a fitting alternative because they are economically accessible. Extensive research has focused on developing nickel-based electrocatalysts for hydrogen and oxygen evolution. Theoretical and experimental work have addressed the elucidation of these electrochemical processes and the role of heteroatoms, structure, and morphology. Even though some works tend to be contradictory, they have lit up the path for the development of efficient nickel-based electrocatalysts. For these reasons, a review of recent progress is presented herein.