Scalable and Engineering Active NiMoO 4 /MoO 2 Catalyst by Rapid Joule Heating toward Industrial Pre-treated Seawater Electrolysis

Abstract

Adopting reverse osmosis (RO) for seawater desalinating is well-established, suitable for coupling with alkaline water electrolysis (ALK) systems. The progressive accumulation of residual ions during the reaction, along with the limited energy efficiency of industrial ALK cells, drives the requirement to explore scalable strategies for engineering highly active catalysts. Herein, a facile water bath followed by rapid Joule heating method has been reported for scalable fabrication of large-scale electrodes. Typically, a cathode of NiMoO 4 /MoO 2 with a size of 10 cm × 10 cm were grown on nickel mesh (NM) substrate.The NiMoO 4 /MoO 2 achieved an overpotential of 345.2/349.2 mV at 500 mA cm -2 in alkaline freshwater/seawater, with stability at 1 A cm -2 for 1000 h. Further experiments in ALK device adopting quasi-industrial condition (6 M KOH RO seawater, 60°C) showed that NiMoO 4 /MoO 2 ||NM delivered a current density of 500 mA cm -2 with a reduction of the required voltage by 1 V in comparison with NM||NM, displaying impressive Faraday efficiency of 90.2% and electricity consumption of 4.48 kWh/Nm 3 H 2 , demonstrating the potential for industrial applications. The characterization and experimental results verified the vital role of Joule heating and the optimised electronic structure in NiMoO 4 /MoO 2 heterostructure, resulting in efficient hydrogen evolution reaction (HER).