Oxygen Vacancies and Interface Engineering on Amorphous/Crystalline CrOx-Ni3N Heterostructures toward High-Durability and Kinetically Accelerated Water Splitting

Manipulating catalytic active sites and reaction kinetics in alkaline media is crucial for rationally designing mighty water-splitting electrocatalysts with high efficiency. Herein, the coupling between oxygen vacancies and interface engineering is highlighted to fabricate a novel amorphous/crystalline CrOx-Ni3N heterostructure grown on Ni foam for accelerating the alkaline hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Density functional theory (DFT) calculations reveal that the electron transfer from amorphous CrOx to Ni3N at the interfaces, and the optimized Gibbs free energies of H2O dissociation (Delta G(H-OH)) and H adsorption (Delta G(H)) in the amorphous/crystalline CrOx-Ni3N heterostructure are conducive to the superior and stable HER activity. Experimental data confirm that numerous oxygen vacancies and amorphous/crystalline interfaces in the CrOx-Ni3N catalysts are favorable for abundant accessible active sites and enhanced intrinsic activity, resulting in excellent catalytic performances for HER and OER. Additionally, the in situ reconstruction of CrOx-Ni3N into highly active Ni3N/Ni(OH)(2) is responsible for the optimized OER performance in a long-term stability test. Eventually, an alkaline electrolyzer using CrOx-Ni3N as both cathode and anode has a low cell voltage of 1.53 V at 10 mA cm(-2), together with extraordinary durability for 500 h, revealing its potential in industrial applications.

Automated summary

This study demonstrates the importance of manipulating catalytic active sites and reaction kinetics in alkaline media for designing efficient water-splitting electrocatalysts. The fabricated amorphous/crystalline CrOx-Ni3N heterostructure shows superior and stable HER activity and optimized OER performance, leading to excellent catalytic performances. The alkaline electrolyzer using CrOx-Ni3N exhibits low cell voltage and extraordinary durability, showing potential for industrial applications.