Rational design of Schottky heterojunction with modulating surface electron density for high-performance overall water splitting

The development of non-precious metal electrocatalysts to synergistically expose more active sites and optimize intrinsic activity still remains a huge challenge. Transition metal layered double hydroxide (LDH) has a great potential in electrocatalysis due to its unique sheet-like nanostructure and low cost. However, the poor electrical conductivity and sluggish water dissociation process hinder their development. Herein, the interface effect of Schottky heterostructure between cobalt-iron hydroxide and MXene and surface electron density modification with phosphorus (P) doping provide an efficient method to solve these crucial issues. The novel Schottky heterostructure catalyst (P-CoFe-LDH@MXene/NF) with self-driven charge transfer can enhance electron transport efficiency. In addition, the surface electron density optimized by P-doping will promote the ability of H+/OH- ion adsorption and redox reaction for overall water splitting. The as-prepared P-CoFe-LDH@MXene/NF requires overpotentials of only 85 mV at 10 mA cm−2 for HER and 252 mV at 200 mA cm−2 for OER in 1.0 M KOH, respectively. And under an alkaline electrolyzer, it can be driven 10 mA cm−2 at a low voltage of 1.52 V for overall water splitting with remarkable durability for 100 h. More broadly, this design concept is universal and it can be extended to design other transition metal-based catalysts. [Display omitted] •The self-supporting P-CoFe-LDH@MXene/NF Schottky heterojunction was prepared successfully.•Surface electronic structure and catalytic kinetics were optimized by P doping.•P-CoFe-LDH@MXene electrode exhibited excellent electrocatalytic activity and low cell voltage.•The mechanism of Schottky heterojunction was explained by the experiment and DFT data.