Efficient Tandem Electrocatalytic Nitrate Reduction to Ammonia on Bimodal Nanoporous Ag/Ag–Co across Broad Nitrate Concentrations
Zixuan Feng, Yuexuan He, Yuhuan Cui, Yanbin Qu, Guopeng Ding, Xue Chen, Chunyu Sui, Qianling Wei, Zhili Wang, Qing Jiang
Abstract
Electrocatalytic nitrate (NO 3 – ) reduction reaction (NO 3 – RR) represents a promising strategy for both wastewater treatment and ammonia (NH 3 ) synthesis. However, it is difficult to achieve efficient NO 3 – RR on a single-component catalyst due to NO 3 – RR involving multiple reaction steps that rely on distinct catalyst properties. Here we report a facile alloying/dealloying-driven phase-separation strategy to construct a bimodal nanoporous Ag/Ag–Co tandem catalyst that exhibits a remarkable NO 3 – RR performance in a broad NO 3 – concentration range from 5 to 500 mM. In 10 and 50 mM NO 3 – electrolytes, the NH 3 yield rates reach 3.4 and 25.1 mg h –1 mg cat. –1 with corresponding NH 3 Faradaic efficiencies of 94.0% and 97.1%, respectively, outperforming most of the reported catalysts under the same NO 3 – concentration. The experimental results and density functional theory calculations demonstrate that Ag ligaments preferentially reduce NO 3 – to NO 2 –, while bimetallic Ag–Co ligaments catalyze the reduction of NO 2 – to NH 3 .