Au nanoparticle incorporated Co(OH)2 hybrid thin film with high electrocatalytic activity and stability for overall water splitting

Cobalt based electrode materials are critical toward the development of renewable energy technologies for fuel production. However, the enhancement of their catalytic activity and stability are key challenges for practical applications. In this study, Au incorporated Co(OH)(2) nanostructures are electrochemically derived from co-deposited cobalt hexacyanoferrate (CoHCF) Au hybrids. This facile approach leads to the creation of Au incorporated amorphous cobalt hydroxide with superior performance for the overall water splitting reaction. This direct electrochemically derived Au-Co(OH)(2) composite exhibits excellent stability for the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in alkaline solutions and overcame, to a significant degree, the critical stability issues inherent to amorphous cobalt oxides. In contrast to Au free Co(OH)(2), the Au incorporated Co(OH)(2) nanocomposite demonstrates excellent bifunctional activity toward OER and HER. The optimized Au-Co(OH)(2) nanomaterials exhibit an OER and HER current density of 10 mA cm(-2) at potentials of 1.61 and -0.424 V, respectively. The Au-Co(OH)(2) hybrid thin film shows small Tafel slopes of 35 and 54 my dec(-1) for the OER and HER reactions, respectively. Moreover, this study provides insights into the formation of Au-Co(OH)(2) hybrid thin films, and the significant role of Au nanoparticles in augmenting the catalytic activity of Co(OH)(2).