Double functionalization of <scp> Mo <sub>2</sub> C </scp> and <scp>NiMn‐LDH</scp> assembling <scp> g‐C <sub>3</sub> N <sub>4</sub> </scp> as efficient bifunctional electrocatalysts for selective electrocatalytic reactions and overall water splitting
Beiyi Zhang, Junqi Li, Qianqian Song, Hui Liu
Abstract
Recently, the development of durable electrocatalysts with bifunctional and high-efficiency applications in overall water splitting has become a hot spot in the energy field. Herein, Mo2C@g-C3N4@NiMn-LDH, a bifunctional electrocatalyst, is obtained through self-assembly strategies of heat treatment, g-C3N4 coating, and hydrothermal growth of NiMn-LDH nanosheets using homogeneous Mo2C precursor nanowire as template. Specifically, Mo2C and NiMn-LDH are located on the inner wall and outer wall of g-C3N4, respectively, realizing separate-sided different functions of g-C3N4 by electronic control of the interface. The Mo2C@g-C3N4@NiMn-LDH composite exhibits excellent bifunctional electrocatalytic performance, in which the inner Mo2C@g-C3N4 are the dominant catalytic active center for hydrogen evolution reaction (HER) and the outer NiMn-LDH acts as co-catalyst, whereas the active center transfer to g-C3N4@NiMn-LDH for oxygen evolution reaction (OER) and the inner Mo2C turns into the co-catalyst. The performance of Mo2C@g-C3N4@NiMn-LDH electrocatalyst is reflected by the overpotential of 116 mV (for HER) and 290 mV (for OER) at the current density of 10 mA cm−2 in alkaline medium, respectively. In addition, the voltage required for overall water splitting to reach 10 mA cm−2 is only 1.587 V, and the sample has excellent stability under constant applied voltage. This work provides a strategy for the development of high-performance electrocatalysts with controllable active sites through interface engineering, so as to achieve competitive equilibrium of different reaction processes.