Mn doping promotes deep surface reconstruction of CoP nanosheet arrays to drive efficient water splitting

Abstract

Among the non-precious metal electrocatalysts, transition metal phosphides (TMPs) show the greatest promise, but their activity and stability still fall short of expectations. Therefore, in order to improve the catalytic activity of TMPs, doping of heteroatoms with different electronegativity becomes one of the best methods. In this paper, the Mn10 doped CoP (the molar amount of Mn accounts for 10% of the total molar amount of metal salts) nanosheet arrays were successfully loaded on coal-based carbon nanofibers (CNFs) via electrodeposition and low-temperature phosphating. Experimentally, the generated electrocatalyst of Mn10-CoP@CNFs demonstrated remarkable catalytic activity at 10 mA cm-2 in 1 M KOH solution, which only needed the overpotentials of 62 mV and 230 mV for hydrogen evolution reaction (HER) and Oxygen Evolution Reaction (OER), respectively. In-situ Raman spectroscopy was used to explore the active intermediates present under catalytic conditions. The results showed that the incorporation of Mn into CoP promoted the formation of the active layered intermediate CoOOH, thus improving the performance of OER. Prominently, at a current density of 10 mA cm-2, the catalyst also exhibited durability of more than 80 hours and an extremely low voltage of 1.537 V when it was used as the full hydrolysis catalyst. This study provides a general approach to the production of high-performance and effective catalysts for water splitting.