Regulation of cerium species in Keggin structure of phosphotungstic acid for efficient nitrogen electroreduction to ammonia

Abstract

As a sustainable and economical strategy, electrochemical nitrogen reduction reaction (eNRR) is a promising alternative of energy-intensive Haber-Bosch process to produce ammonia. Fabricating efficient catalysts for eNRR is still challenging due to the bottleneck of insufficient activity and low electron selectivity. Herein, phosphotungstic acid (PTA) as substrate to anchor cerium species on the 4-fold hollow site was prepared, which reaches high ammonia yield rates of 42 μg h−1 mgcat−1 and Faradaic efficiencies of 9.2 % at −0.6 V versus reversible hydrogen electrode. Experiments and theoretical calculations reveal that the introduction of Ce species could significantly improve the electronic density of adjacent exposed W atoms, further boosting the effective adsorption and activation of N2 to form active *N2. Finally, the designed Ce-PTA catalysts show high electrocatalytic activity of N2 reduction into ammonia. This work highlights the important role of using PTA as substrate to prepare stable supported metal species for heterogeneous electrocatalysis.