Highly Efficient and Stable Catalyst Based on Co(OH)₂@Ni Electroplated on Cu-Metallized Cotton Textile for Water Splitting

The concept of using renewable energy to power water electrolyzers is seen as a favorable approach for the production of green and sustainable hydrogen. The electrochemical water splitting can be significantly and efficiently enhanced using bifunctional catalysts, which are active toward both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). Herein, a stable and high-performance catalyst based on hybrid-metal/metal-hydroxide nanosheet arrays electroplated onto Cu-metallized cotton textile (Co(OH)₂@Ni) was designed and fabricated as a bifunctional electrocatalyst for complete water-splitting reactions. It was found that the interconnected α-Co(OH)₂ nanosheets were evenly formed onto the metalized cotton textile, and the optimized Co(OH)₂@Ni sample exhibited an overpotential of +96 mV at 10 mA cm^-2, with excellent stability toward HER. The as-prepared catalyst also showed superior electrochemical activity and durability toward OER, which was found to be comparable to those of conventional precious group metal-based catalysts. In addition, when Co(OH)₂@Ni were assembled as electrodes in a water electrolyzer (1 M KOH), a cell voltage of 1.640 V was achieved at a current density of 10 mA cm^-2, enabling it to be a promising bifunctional catalyst for water electrolysis in real applications.