Tunable d‐Band Centers of Ni<sub>5</sub>P<sub>4</sub> Ultra‐Thin Nanosheets for Highly‐Efficient Hydrogen Evolution Reaction
Chengcheng Miao, Yanmei Zang, Hang Wang, Xinming Zhuang, Ning Han, Yanxue Yin, Yandong Ma, Ming Chen, Ying Dai, SenPo Yip, Johnny C. Ho, Zaixing Yang
Abstract
Abstract Although the recent advance of ultra‐thin 2D nanosheets for hydrogen evolution reaction (HER) is remarkable, there are still substantial challenges to reliably control their physioelectric and electrochemical properties to employ as highly‐efficient electrocatalysts. Herein, based on complementary theoretical and experimental studies, the d‐band center position of ultra‐thin 2D Ni 5 P 4 nanosheets can be manipulated by simple heteroatom doping. Interestingly, the Fe‐doped nanosheets yield the lowest d‐band center position, but they do not display the optimal Gibbs free energy of adsorbed H atoms due to the imbalance of adsorption and desorption of adsorbed H atoms. With the proper Co doping (i.e., 20%), the nanosheets exhibit the best electrocatalytic performance along with an excellent stability. The overpotential is only 100.5 mV at 10 mA cm −2 with a Tafel slope of 65.8 mV dec −1 , which is superior than those of Fe‐doped, Cu‐doped, and pristine Ni 5 P 4 nanosheets. Ultraviolet photoelectron and X‐ray photoelectron spectroscopy further verify the downshift of d‐band centers of nanosheets by optimal doping, illustrating that Ni with the lower binding energy mainly dominates the active sites. All these results provide a valuable design scheme of dopants to control the d‐band center position of nanosheets for next‐generation highly‐efficient HER electrocatalysts.