Synthesis of nanoflower-like NF@MoSCo/Co2P composites for overall seawater splitting

Abstract

In recent years, a variety of methods have been reported to produce hydrogen by electrolysis of water. However, the design of low-cost electrocatalysts is still a great challenge because of the slow dissociation kinetics of water molecules and the poor long-term stability of catalysts in the HER/OER process. In this paper, sulfur-doped molybdenum and cobalt composites (NF@MoSCo) were prepared on the surface of nickel foam (NF) using a facile hydrothermal reaction. After further low-temperature phosphating treatment, nanoflower-like structure composites (NF@MoSCo/Co₂P) can be prepared with excellent electrocatalytic properties both for the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). The as-synthesized composites show an overpotential of 176.3 mV at 100 mA cm⁻² for the OER and 180.3 mV at 100 mA cm⁻² for the HER. Thus, a symmetric device consisting of Mo and Co-based phosphide nanoflower electrodes was constructed for overall seawater splitting, which can provide a potential of 1.62 V at 100 mA cm⁻² in alkaline simulated seawater (1 M KOH + 0.5 M NaCl). This provides a new idea for producing low-resistance and high-efficiency catalysts.