Nitrogenase-Inspired Vs-MoS<sub>2</sub>/Vo-Fe<sub>2</sub>O<sub>3</sub> Heterojunction with Fixed Molar Ratio Promotes Bifunctional Nitrogen Fixation
Xinyu Chen, Shuang Wu, Jikang Wang, Jikang Wang, Bo Li, Lian Xiao, Jiaqi Lv, Qianqian Liu, Yunzuo Cui, Jianxin Ma, Weibo Ren, Yufei Zhao, Li‐Kai Yan, Jiawei Wang, Jiawei Wang, Hong‐Ying Zang
Abstract
The development of efficient heterojunction catalysts for electrochemical bifunctional nitrogen reduction reaction (NRR) and nitrate reduction reaction (NO 3 RR) as a replacement for the Haber–Bosch (H–B) process is on the stage, yet the controlled synthesis of heterojunction catalysts with fixed composition ratios remains a formidable challenge. Herein, we employed oxygen-rich polyoxometalates (POMs) as precursors to form a metal sulfide/metal-oxide heterojunction catalyst via the one-pot method, specifically nanoflower-like MoS 2 /Fe 2 O 3 heterojunctions enriched with vacancies (Vs-MoS 2 /Vo-Fe 2 O 3 ). Notably, the composition ratio of the heterojunction precisely mirrors the proportion of metal components in the POMs. This catalyst has demonstrated efficient all-pH nitrogen reduction activity, with the highest performance observed in acidic electrolytes (NH 3 yield rate = 73.14 ± 1.35 μg h –1 mg –1 cat., Faraday efficiency = 42.68 ± 2.12%). Simultaneously, it exhibits superior nitrate reduction activity in neutral electrolytes (Selectivity = 97.50 ± 0.75%, Faraday efficiency = 80.39 ± 3.71%). In situ Raman spectroscopy, extended X-ray absorption fine structure spectroscopy (EXAFS) combined with Density functional theory (DFT) calculations have verified that superior catalytic activity of Vs-MoS 2 /Vo-Fe 2 O 3 can be primarily attributed to facile N 2 adsorption at S vacancies, an electronic coupling between Fe and Mo, enhanced conductivity at heterojunctions, and a reduced Gibbs free energy for NH* hydrogenation to NH 2 * at O vacancies.