Sunlight-driven Monolithic Water Splitting Device Using the Anodized Ni-Fe Catalytic Substrate for Oxygen Evolution Reaction

Abstract

Large-scale industrial application of solar-driven water splitting has called for the development of oxygen evolution reaction (OER) catalysts that deliver high catalytic ac-tivity and stability. Here we show that an efficient OER catalytic substrate can be devel-oped by roll-to-roll fabrication of electrodeposited Ni-Fe foils, followed by anodization. An amorphous oxyhydroxide layer directly formed on Ni-Fe foils exhibited high catalytic activity towards water oxidation in 1 M KOH solution, which required an overpotential of 0.251 V to reach current density of 10 mA/cm2. The developed catalytic electrode showed the best OER activity among catalysts with film structure. The catalyst also showed pro-longed stability at vigorous gas evolution condition for 36 h. To demonstrate the monolith-ic photo-assisted water splitting device, an amorphous silicon solar cell was fabricated on Ni-Fe catalytic substrate, resulting in lowering OER overpotential under light-illumination. This monolithic device is the first demonstration that the OER catalytic substrates and the solar cells are integrated, and can be easily applied for industrial scale solar-driven water electrolysis.