Construction of Co3S4/MoS2 p-p heterojunction as an efficient catalyst for water splitting and electrochemical oxidation of organic molecules

Abstract

Electrolysis of wastewater containing urea or small organic molecules while obtaining hydrogen energy is a promising strategy for realizing energy acquisition and environmental protection. Construction of semiconductor heterojunctions to regulate the transfer of interfacial electrons has been regarded as an efficient approach to improve the electrocatalytic performance of oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) for the materials, and obtain the bifunctional electrocatalysts aiming to construct a water splitting cell using one non-precious metal material. Herein, a bifunctional Co3S4/MoS2 electrocatalyst with a p-p heterojunction and hollow structure has been successfully prepared through the precipitation-hydrothermal method, which presents the high bifunctional electrocatalytic performance due to the formed path of electron transfer in the heterojunction interface being favorable for OH- adsorption. The accelerated electron transfer in heterojunction interfaces endows Co3S4/MoS2 presenting the superior electrocatalytic performance including OER, urea oxidation reaction (UOR) and oxygen evolution reaction in lactic acid solution (OER-LA). At 50 mA cm−2, the voltages of HER, OER, UOR and OER-LA are −0.123, 1.511, 1.400, 1.440 V vs. RHE, respectively. In a two-electrode electrolytic cell using Co3S4/MoS2 as anode and cathode displays the outstanding electrocatalytic performance in 1 M KOH, 1 M KOH containing 0.5 M urea, and 1 M KOH containing 0.5 M lactic acid electrolytes, superior to the most reported materials. This research provides a strategy for the construction of advanced bifunctional electrocatalysts using metal sulfides to form heterojunction for realizing the high bifunctional catalytic activities in hydrogen production and organic molecule decontamination.