VFe@Ni/Ni3N Mott-Schottky heterojunction induced electronic modulation for efficient alkaline water splitting

Abstract

Designing affordable and productive bifunctional electrocatalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) has been a long-term goal of anion exchange membrane water electrolysis (AEMWE). Heteroatoms doping and heterostructure construction are generally considered as effective methods for electrocatalysts modification. Herein, V and Fe co-doped Ni/Ni3N (VFe@Ni/Ni3N) electrocatalyst with a Mott-Schottky heterostructure was prepared by hydrothermal and NH3 reduction methods. The formation of Ni/Ni3N Mott-Schottky heterojunction can effectively trigger the self-driven carrier transfer on the heterointerfaces, thus accelerating charges achievement to the surface active sites and advancing the catalytic efficiency. Meanwhile, the co-doping of V and Fe lowers the flat-band potential of Ni/Ni3N, leading to greater electron density, which increases the electron transport potentiality and facilitates the adsorption and reduction of H* in the HER process. Therefore, a remarkable performance for HER with overpotentials of 47 and 180 mV at 10 and 200 mA cm−2 in alkaline solution was achieved. Significant progress has also been made in OER and the full water electrolysis. Furthermore, for the AEMWE with VFe@Ni/Ni3N, a low applied cell voltage of only 1.75 V was needed to reach a high current density of 600 mA cm−2 with an impressive long-term stability of 100 h. This study supplies an innovative strategy of electronic modulation by co-doping and Mott-Schottky heterojunction construction, which is referential for the advancement of economic electrocatalysts for sustainable energy systems.