Self-Supporting Fe, Ni-Codoped CoS2 Hollow Microtube Arrays Electrode as an Effective Catalyst for Alkaline Ethanol-Assisted Overall Water Splitting.

Electrocatalytic oxidation of biomass molecules such as ethanol in hybrid alkaline water electrolysis is more thermodynamically favorable and techno-economic attractive to replace conventional pure water electrooxidation to produce green hydrogen. Herein, the flexible and binder-free hollow microtube catalyst arrays of CoS2/CC, Ni0.04Co0.96S2/CC, Fe0.07Ni0.04Co0.89S2/CC, and Fe0.08Ni0.10Co0.82S2/CC were derived from metal-organic framework arrays anchored on carbon cloth (CC). These arrays exhibited favorable performance in electrochemical water oxidation, ethanol oxidation, and hydrogen evolution processes, because of their obvious advantages in high conductivity and long-term stability. The optimized self-supporting Fe0.08Ni0.10 Co0.82S2/CC electrode composed of a 3D hollow porous microtube structure only needs a low potential of 1.412 and 1.267 V (vs. RHE) to deliver 10 mA cm-2 current density for alkaline water and ethanol oxidation reactions, respectively. Simultaneously, the pure CoS2/CC electrode presents excellent alkaline hydrogen production property among the series self-supporting electrodes with a low overpotential of 188 mV at 10 mA cm-2. In this work, it is proved that the hybrid water splitting system, using Fe0.08Ni0.10Co0.82S2/CC and CoS2/CC as anode and cathode, respectively, can effectively reduce the cell voltage to 1.479 V to deliver 10 mA cm-2 with high pure hydrogen generation and high valued potassium acetate generation.