pH‐Dependent Electroreduction of Nitrate on Fe Single‐Atom Catalyst
Zhen Meng, Adyasa Priyadarsini, Kaige Shi, Zhuanghe Ren, Debit Subedi, Deborah Israel, William E. Kaden, Xiaofeng Feng, Shyam Kattel
Abstract
Electrochemical nitrate reduction reaction (NO 3 RR) has received considerable attention due to its potential for the denitrification of wastewater and sustainable NH 3 production. Among various catalysts for NO 3 RR, Fe−N−C single‐atom catalyst has attracted significant interest due to its well‐defined active sites and high stability across various media. Here, we investigate the pH dependence of NO 3 RR on Fe−N−C by combining experiments and density functional theory (DFT) calculations. The Fe−N−C catalyst achieves high activity and >80% Faradaic efficiency for NH 3 production in the NO 3 RR across acidic, neutral, and alkaline electrolytes, while the hydrogen evolution reaction (HER) exhibits the strongest competition with NO 3 RR in alkaline electrolyte. DFT calculations identify the NHO*‐mediated pathway as the most favorable for NO 3 RR on Fe−N−C and further reveal the pH dependence of the potential‐determining steps for both NO 3 RR and HER, elucidating the origin of the pH‐dependent selectivity. Our studies provide new mechanistic insights into the NO 3 RR on single‐atom catalysts and guide the design of broad pH‐range electrocatalysts for efficient and versatile nitrate recycling.