Three-Dimensional Heterostructured CoSe₂/MoSe₂@CC as Trifunctional Electrocatalysts for Energy-Efficient Hydrogen Production

Abstract

Electrochemical water cracking to hydrogen production is a key technology for storing and converting energy. However, the energy consumption of this method comes mainly from the slow anodic oxygen evolution reaction (OER). Replacement of the OER with the urea oxidation reaction (UOR) enables energyefficient hydrogen production, avoiding dangerous H 2 /O 2 mixtures due to the release of N 2 and CO 2 at the anode. Hence, it is crucial to investigate efficient multifunctional electrocatalysts to assist OER in combination with hydrogen evolution reaction (HER) in improving the energy efficiency of hydrogen production. In this work, we take a feasible strategy to synthesize three-dimensional (3D) highly active catalysts CoSe 2 / MoSe 2 grown on carbon cloth (CoSe 2 /MoSe 2 @CC). Taking advantage of synergistic interaction between interfaces, CoSe 2 /MoSe 2 @CC exhibits a promising overpotential of 71 and 320 mV for HER and OER at 10 mA cm −2 , respectively. In addition, CoSe 2 / MoSe 2 @CC-4 also showed prominent catalytic activity against UOR in 1 M KOH with 0.3 M urea. An electrolyzer is also constructed via using CoSe 2 /MoSe 2 @CC as both electrodes. It is worth mentioning that the electrolyzer CoSe 2 /MoSe 2 @CC∥CoSe 2 /MoSe 2 @CC in 1 M KOH with 0.3 M urea obtains a battery voltage of 1.48 V to generate a current density of 10 mA cm −2 , which is 0.17 V lower than that in 1 M KOH (1.65). This electrolyzer completed relatively conspicuous durability in an alkaline electrolyte solution of 1 M KOH, with maintenance of initial current density through 24 h of continuous operation at a constant cell voltage for water splitting. This work develops a promising multifunctional catalyst for urea-assisted hydrogen generation from water electrolysis, which can reduce the decomposition potential of water electrolysis.