Rapid synthesis of efficient Mo-based electrocatalyst for the hydrogen evolution reaction in alkaline seawater with 11.28% solar-to-hydrogen efficiency

Abstract

Herein, we applied a rapid Joule heating method to fabricate MoNi₄ nanoparticles anchored on MoO_x nanorods (MoNi₄/MoO_x) for the electrocatalytic splitting of seawater. Compared to the traditional calcination method, the Joule heating method not only shortened the preparation time, but also modulated the chemical states of the reactive sites and further improved the electrocatalytic activity. As-prepared MoNi₄/MoO_x achieved overpotentials of 15 mV (@10 mA cm⁻²) and 227 mV (@1000 mA cm⁻²) in alkaline seawater electrolyte for the hydrogen evolution reaction. This composite also exhibited excellent chemical stability in 1000 h testing at a constant current density of 1 A cm⁻². Moreover, the MoNi₄/MoO_x showed great performance in a membrane electrode assembly (MEA) electrochemical reactor, which reduced the energy needed by 3.33 kW h to generate per cubic meter of H₂ at a current density of 200 mA cm⁻² relative to a commercial Ni foam system. Finally, a home-made solar power-assisted water splitting device was successfully constructed using MoNi₄/MoO_x//RuO₂ electrodes and polymer solar cells (PSCs), achieving a solar-to-hydrogen (STH) efficiency of 11.28%.