Acidic Nitrate Electroreduction with Ultrahigh Energy Efficiency
Rong Zhang, Xintao Ma, Shaoce Zhang, Huilin Cui, Chuan Li, Yanbo Wang, Qing Li, Chao Peng, Ying Guo, Chunyi Zhi
Abstract
Abstract Ammonia (NH 3 ) is an important feedstock for industry, an ideal energy carrier, and a perspective storage media for hydrogen. Recently, electrochemical nitrate (NO 3 −) reduction under acidic conditions has received considerable attention but it suffers from limited efficiency especially under low NO 3 − concentration. Here, we report an in situ formed positively charged polyethyleneimine‐modified Cu under acidic conditions as a catalyst‐electrolyte interface (CEI) for electrochemical NO 3 − reduction to NH 3 . Such CEI can effectively accumulate NO 3 − anions via static interactions and accelerate *NO hydrogenation to *NOH by weakening *NO intermediate adsorption on Cu site, thereby facilitating NO3−‐to‐NH 3 conversion. Such CEI delivers an increased NH 3 Faradaic efficiency (FE) of 83.5% and an impressive half‐cell energy efficiency (EE) of 37.1% in 10 mM NO 3 − solution (pH = 1). The NH 3 FE and EE can further increase to 90.2% and 44.1% in 0.5 M NO 3 −, respectively. The high EE of CEI surpasses previously reported catalyst performances for NO 3 − reduction. Finally, we demonstrate the feasibility of a novel NO 3 −‐furfural battery, showcasing a self‐power electrocatalytic system capable of simultaneously treating NO 3 − pollutants, generating value‐added NH 3 and upgrading biomass. This work offers valuable insights into the construction of a CEI to enhance the efficiency of NH 3 synthesis.