Honeycomb-like MXene/NiFeP <sub> <i>x</i> </sub>–NC with "continuous" single-crystal enabling high activity and robust durability in electrocatalytic oxygen evolution reactions
Xiaojun Zeng, Yifei Ye, Yongqing Wang, Ronghai Yu, Martin Moskovits, Galen D. Stucky
Abstract
The development of low-cost, stable, and robust non-noble metal catalysts for water oxidation is a pivotal challenge for sustainable hydrogen production through electrocatalytic water splitting. Currently, such catalysts suffer from high overpotential and sluggish kinetics in oxygen evolution reactions (OERs). Herein, we report a "continuous" single-crystal honeycomb-like MXene/NiFeP<sub><i>x</i></sub>–N-doped carbon (NC) heterostructure, in which ultrasmall NiFeP<sub><i>x</i></sub> nanoparticles (NPs) encapsulated in the NC are tightly anchored on a layered MXene. Interestingly, this MXene/NiFeP<sub><i>x</i></sub>–NC delivers outstanding OER catalytic performance, which stems from "continuous" single-crystal characteristics, abundant active sites derived from the ultrasmall NiFeP<sub><i>x</i></sub> NPs, and the stable honeycomb-like heterostructure with an open structure. The experimental results are rationalized theoretically (by density functional theory (DFT) calculations), which suggests that it is the unique MXene/NiFeP<sub><i>x</i></sub>–NC heterostructure that promotes the sluggish OER, thereby enabling superior durability and excellent activity with an ultralow overpotential of 240 mV at a current density of 10 mA·cm<sup>−2</sup>.