Co3S4/MnS p-p heterojunction as a highly efficient electrocatalyst for water splitting and electrochemical oxidation of organic molecules

Abstract

In this work, Co₃S₄/MnS p-p heterojunction catalyst with hollow structure was successfully synthesized by one-step hydrothermal method. For oxygen evolution reaction (OER), urea oxidation reaction (UOR), lactate oxidation reaction (OER-LA) and glucose oxidation reaction (GOR), 1.59 V, 1.49 V, 1.54 V and 1.40 V vs. RHE are required to drive a current density of 50 mA cm⁻², respectively, and the overpotential of hydrogen evolution reaction (HER) in 1 M KOH is 0.193 V at 50 mA cm⁻². For the two-electrode overall water splitting in 1 M KOH, 1 M KOH containing 0.5 M urea, 1 M KOH containing 0.125 M lactate electrolyte and 1 M KOH containing 0.3 M glucose, water splitting voltages are only required at 1.73 V, 1.60 V, 1.62 V and 1.63 V to drive the current density of 50 mA cm⁻². Moreover, its activity does not attenuate significantly in 1 M KOH containing 0.125 M lactate after continuous operation at 50 mA cm⁻² for 200 h, showing excellent durability. In addition, the technology of glucose oxidation assisted water splitting for hydrogen production has been preliminarily explored, which also has excellent HER performance. Density functional theory (DFT) show that the p-p heterojunction between Co₃S₄ and MnS is conducive to the redistribution of electrons at the interface, thus promoting electron migration. Finally, the water splitting cell coupled with lactic acid oxidation reaction using polylactic acid pipette as source also exhibits high activity and stability. This study provides another idea and strategy for hydrogen production while waste plastic treatment.