Tunable d‐Band Centers of Ni5P4 Ultra‐Thin Nanosheets for Highly‐Efficient Hydrogen Evolution Reaction

• Published in: Advanced materials interfaces Vol. 9; no. 22
• Main Authors: Miao, Chengcheng, Zang, Yanmei, Wang, Hang, Zhuang, Xinming, Han, Ning, Yin, Yanxue, Ma, Yandong, Chen, Ming, Dai, Ying, Yip, SenPo, Ho, Johnny C., Yang, Zai‐xing
• Format: Journal Article
• Language: English
• Published: Weinheim John Wiley & Sons, Inc 01.08.2022
• Subjects: Doping; d‐band center; Electrocatalysts; Electrochemical analysis; Gibbs free energy; hydrogen evolution reaction; Hydrogen evolution reactions; Nanosheets; Ni 5P 4; Photoelectrons; ultra‐thin nanosheets
• DOI: 10.1002/admi.202200739
• ISSN: 2196-7350

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 Ni5P4 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 Ni5P4 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. The d‐band center of Ni5P4 ultra‐thin nanosheets can be manipulated by simply doping with heteroatoms of Co, Fe, and Cu. By designing and tuning the d‐band center to the optimized position, 20% Co‐doped Ni5P4 ultra‐thin nanosheet exhibits an overpotential as low as 176.8 mV at 100 mA cm−2 with a Tafel slope of 65.8 mV dec−1.