Effect of in-plane Mott-Schottky on the hydroxyl deprotonation in MoS@CoS/NC heterostructure for efficient overall water splitting.

The development of clean energy sources such as hydrogen is indispensable for achieving the long-term goal of carbon neutrality by the mid-century. The utilization of renewable energy for power generation to electrolyze water for hydrogen production is one of the most desirable green hydrogen production methods. The cathode side of the decomposing water undergoes the oxygen precipitation reaction, and the oxygen precipitation mechanism can be divided into the adsorbed evolution mechanism (AEM) and lattice oxygen oxidation mechanism (LOM). Based on the adsorbed evolution mechanism (AEM), the deprotonation (DeP) process involving multiple electron transfers is central to determining the oxygen release. DeP is essentially a proton-transfer process that allows for the establishment of a bifunctional catalyst system with both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Consequently, an all-transition-metal-based MoS@CoS/NC heterostructure was designed and constructed in this study for the efficient total decomposition of water. The MoS@CoS/NC catalyst achieved the HER and OER current densities of 10 mA cm at the low overpotential (56 mV, 243 mV) and showed excellent long-term durability among all samples. The Mott-Schottky effect is considered the driving force for the HER and DeP in the OER. This study proposes a rational design for bifunctionalized non-precious metal electrolytic water catalysts using the Mott-Schottky effect as a criterion.