Mott-Schottky contact synergistically boosts the electroreduction of nitrate to ammonia under low-nitrate concentration

• Published in: Energy & environmental science 2024-04, Vol.17 (8), p.298-292
• Main Authors: Zhu, Xiaojuan, Ma, Chaoqun, Wang, Yi-Chi, Qu, Kaiyu, Song, Leyang, Wang, Jing, Gong, Yushuang, Liu, Xiang, Zhang, Jintao, Lu, Qipeng, Wang, An-Liang
• Format: Article
• Language: English
• Subjects: Ammonia; Availability; Batteries; Catalysts; Chemical reduction; Cobalt oxides; Electrocatalysts; Energy consumption; Groundwater; Groundwater pollution; Hydrogen; Kinetics; Nitrate reduction; Nitrates; Reaction kinetics; Zinc
• ISSN: 1754-5692; 1754-5706
• DOI: 10.1039/d4ee00715h

The electrocatalytic nitrate reduction reaction (NO 3 RR) holds tremendous potential for remediating NO 3 − pollution in groundwater and obtaining clean ammonia (NH 3 ). However, the currently reported NO 3 RR catalysts face challenges in achieving high conversion efficiency at low NO 3 − concentrations due to sluggish reaction kinetics. Herein, we present a highly efficient Mott-Schottky electrocatalyst, composed of an amorphous Co-B nanochain embedded in amorphous CoO x nanosheets (Co-B@CoO x ). In 100 ppm NO 3 − -N, the Co-B@CoO x catalyst exhibits remarkable performance, achieving over 95% NO 3 − removal within 40 min at −0.90 V vs. reversible hydrogen electrode and nearly 100% NH 3 selectivity at −0.80 V, surpassing the performance of both Co-B and CoO x catalysts. Furthermore, Co-B@CoO x demonstrates an ultra-low energy consumption of 0.39 kW h mol NO 3 −1 , establishing it as one of the most active catalysts available. Comprehensive experimental investigations and theoretical calculations indicate that the high conversion efficiency of Co-B@CoO x originates from the formation of local nucleophilic/electrophilic regions at the Co-B/CoO x Mott-Schottky interface, which effectively optimizes the targeted adsorption behavior of NO 3 − at the Co-B site and H 2 O at the CoO x site, thereby enhancing simultaneously NO 3 − affinity and active hydrogen availability. Furthermore, a novel Zn-NO 3 − battery utilizing the Co-B@CoO x catalyst delivers a remarkable power density of 4.78 mW cm −2 , outperforming most recently reported Zn-NO 3 − batteries. A Mott-Schottky electrocatalyst composed of amorphous Co-B nanochain embedded in amorphous CoO x nanosheets was developed for highly efficient conversion of NO 3 − -to-NH 3 .