Efficient Nitrate to Ammonia Conversion on Bifunctional IrCu<sub>4</sub> Alloy Nanoparticles
Ning He, Yuan Zhi, Chao Wu, Shibo Xi, Jingjing Xiong, Yucong Huang, Guanwu Lian, Zuliang Du, Laihao Liu, Dawei Wu, Zhongxin Chen, Wenguang Tu, Zhigang Zou, S. Y. Tong
Abstract
Electrochemical nitrate reduction (NO 3 RR) to ammonia presents a promising alternative strategy to the traditional Haber–Bosch process. However, the competitive hydrogen evolution reaction (HER) reduces the Faradaic efficiency toward ammonia, while the oxygen evolution reaction (OER) increases the energy consumption. This study designs IrCu 4 alloy nanoparticles as a bifunctional catalyst to achieve efficient NO 3 RR and OER while suppressing the unwanted HER. This is achieved by operating the NO 3 RR at positive potentials using the IrCu 4 catalyst, which allows a Faradaic efficiency of 93.6% for NO 3 RR. When applied to OER catalysis, the IrCu 4 alloy also shows excellent results, with a relatively low overpotential of 260 mV at 10 mA cm –2 . Stable ammonia production can be achieved for 50 h in a 16 cm 2 flow electrolyzer in simulated working conditions. Our research provides a pathway for optimizing NO 3 RR through bifunctional catalysts in a tandem approach.