Study of Active Sites on Se-MnS/NiS Heterojunctions as Highly Efficient Bifunctional Electrocatalysts for Overall Water Splitting
Mn-based sulfides have been used as in oxygen reduction reaction, lithium-ion battery and supercapacitor. Few Mn-based catalysts were reported for OER or HER due to the poor catalytic activity. Mn is commonly used as a dopant to tune the electronic structure of electrocatalyst. It is thus a challenge to achieve the highly efficient OER and HER activities for overall water slitting on Mn-based catalysts. In this work, we for the first time synthesize a Se-MnS/NiS electrocatalyst through facile hydrothermal and chemical deposition treatments. Introduction of Se dopants can tailor the structure, and generate more electrochemically active surface areas, favorable for electrocatalyzing HER and OER activities. Besides, the synergistic effect of Se-MnS/NiS heterojunction promotes the adsorption of hydrogen atom on the surface of catalyst compared to the NiSe, NiS, or Se-NiS. The resulting Se-NiS/MnS catalyst requires an overpotential as low as 56 mV and 211 mV to deliver 10 mA cm-2 for HER and OER in alkaline media, respectively. Furthermore, the Se-MnS/NiS directly used as bifunctional electrodes for overall water splitting exhibits a relatively low voltage of 1.47 V at 10 mA cm-2, and a remarkable durability for 48 h, which is considered as one of promising bifunctional Mn-based electrocatalyst candidates instead of precious metal-based electrocatalysts for the efficient water splitting.
- This article is part of the themed collection: 2019 Journal of Materials Chemistry A HOT Papers