Regulating d-p band center with selenium vacancy in iron diselenide nanoarrays towards sulfion-assisted seawater electrolysis for chlorine-free hydrogen production
Xinzhi Wang, Jing Jiang, Jiayi Zhang, Qiyao Zeng, Aike Liu, Lunhong Ai
Abstract
Defect engineering is considered one of the most powerful strategies for regulating the catalytic activity of electrocatalysts. A deep understanding of the defect-involved mechanism in electrocatalytic process is of great importance but remains a challenging task. In this study, an anionic Se-vacancy (V Se ) was introduced into iron diselenide (FeSe 2 ) nanoarrays, enabling the catalyst to exhibit improved electrocatalytic performance for sulfion oxidation reaction (SOR). The Se vacancy incorporated can modulate surface electronic structure and optimize the proximity of the d-p band center, strengthening the interaction between FeSe 2 -V Se and S atom. This endows the FeSe 2 /IF-V Se catalyst with the excellent electrocatalytic activity for SOR. As an alternative reaction to oxygen evolution reaction (OER), the low-potential SOR enables an ultralow electricity consumption in SOR-hydrid seawater electrolysis, avoiding detrimental chlorine electrochemistry. A proof-of-concept self-powered system based on FeSe 2 -V Se electrodes was constructed by integrating Zn-nitrite battery and SOR-hybrid seawater electrolyzer to produce high-value hydrogen, sulfur and ammonia. This work offers a fascinating strategy for the construction of an advanced energy system to produce hydrogen while utilizing seawater and wastewater.