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.

Automated summary

The study explores enhancing the electrocatalytic efficiency of transition metal layered double hydroxide through Schottky heterostructure and phosphorus doping, improving the activity of water dissociation and oxygen evolution reactions. The P-CoFe-LDH@MXene/NF catalyst can achieve efficient water splitting at low overpotentials and shows remarkable durability.