Hierarchical nanostructure with ultrafine MoO3 particles-decorated Co(OH)2 nanosheet array on Ag nanowires for promoted hydrogen evolution reaction

Abstract It is an efficient and green way to obtain hydrogen with the assistance of highly active and low-cost electrocatalysts by using the electrochemical water electrolysis process in the alkaline electrolyte. Herein, MoO3 particles-decorated Co(OH)2 nanosheet array with a hierarchical nanostructure wrapped Ag nanowires (MoO3-Co(OH)2@Ag NWs) electrocatalysts have been constructed via a two-step electrodeposition method. Ag nanowires have functioned as a conductive network to improve electron transportation ability. As-prepared MoO3-Co(OH)2@Ag NWs catalysts show good HER performance compared with the original Co(OH)2 by delivering at a low overpotential of 220 mV at a current density of −100 mA cm−2, while those for pristine Co(OH)2 and MoO3 are 290 and 412 mV, respectively. The good durability performance of the MoO3-Co(OH)2@Ag NWs catalyst can last for 29 h at a high current density of 100 mA cm−2 with negligible loss, demonstrating the possible commercial application in electrochemical water splitting. A theoretical study has been carried out to understand the reaction kinetics in the generated heterostructure (MoO3-Co(OH)2), which can significantly promote hydrogen evolution reaction process with the reduced adsorption energy of water (Δ G H 2 O *) and decreased Gibbs free-energy of adsorbed H* (ΔGH*) during the hydrogen evolution reaction process. This work can help us to design high-active catalysts with the heterointerface-dependent mechanism for electro-catalytic water splitting processes.