Accelerating water dissociation kinetics of Ni3N by tuning interfacial orbital coupling
Yishang Wu, Yufang Xie, Shuwen Niu, Yipeng Zang, Jinyan Cai, Zenan Bian, Xuanwei Yin, Yanyan Fang, Da Sun, Di Tao Niu, Zheng Lu, Amirabbas Mosallanezhad, Huijuan Wang, Dewei Rao, Hongge Pan, Gongming Wang
Abstract
The high unoccupied d band energy of Ni3N basically results in weak orbital coupling with water molecule, consequently leading to slow water dissociation kinetics. Herein, we demonstrate Cr doping can downshift the unoccupied d orbitals and strengthen the interfacial orbital coupling to boost the water dissociation kinetics. The prepared Cr-Ni3N/Ni displays an impressive overpotential of 37 mV at 10 mA·cmgeo−2, close to the benchmark Pt/C in 1.0 M KOH solution. Refined structural analysis reveals the Cr dopant exists as the Cr-N6 states and the average d band energy of Ni3N is also lowered. Density functional theory calculation further confirms the downshifted d band energy can strengthen the orbital coupling between the unpaired electrons in O 2p and the unoccupied state of Ni 3d, which thus facilitates the water adsorption and dissociation. The work provides a new concept to achieve on-demand functions for hydrogen evolution catalysis and beyond, by regulating the interfacial orbital coupling.