posted on 2021-08-25, 20:29authored byDongxu Zhang, Weixuan Dong, Yanhong Liu, Xiaoqing Gu, Tianyu Yang, Qiang Hong, Di Li, Dongqi Zhang, Hongbo Zhou, Hui Huang, Baodong Mao, Zhenhui Kang, Weidong Shi
Photoassisted
electrocatalysis (P-EC) emerges as a rising star
for hydrogen production by embedding photoactive species in electrocatalysts,
for which the interfacial structure design and charge transfer kinetics
of the multifunctional catalysts remain a great challenge. Herein,
Zn-AgIn5S8 quantum dots (ZAIS QDs) were embedded
into 2D NiFe layered double hydroxide nanosheets through a simple
hydrothermal treatment to form 0D/2D composite catalysts for P-EC.
With evidence from transient photovoltage spectroscopy, we acquired
a clear and fundamental understanding on the kinetics of charge extraction
time and extraction amount in the 0D/2D heterojunctions that was proved
to play a key role in P-EC. Upon light illumination, for HER, the
optimized NiFe-ZAIS exhibits obviously reduced overpotentials of 129
and 242 mV at current densities of 10 and 50 mA cm–2, which are 22 and 33 mV lower than those of dark electrocatalysis,
respectively. For OER, the NiFe-ZAIS electrode also shows low overpotentials
of 220 and 268 mV at current densities of 10 and 50 mA cm–2, respectively, under light illumination, which were able to almost
double the intrinsic activity. Finally, with NF@NiFe-ZAIS as both
the cathode and the anode, the assembled electrolyzer only requires
1.62 V to reach the overall water splitting current density of 10
mA cm–2 under P-EC. This work provides a useful
example for the profound understanding of the design and the kinetics
study of multifunctional P-EC catalysts.