Oxygen Vacancy Regulation Strategy Promotes Electrocatalytic Nitrogen Fixation by Doping Bi into Ce-MOF-Derived CeO2 Nanorods

Although the mature Haber-Bosch process has become the main method for ammonia production, its high energy consumption nature has motivated people to learn about nitrogenases, which can fix N-2 in the atmosphere to NH3 under ambient conditions. Here we show that Bi-CeO2 nanorods with oxygen vacancies can effectively fix N-2 to NH3 under ambient conditions by an electrocatalytic nitrogen reduction reaction (NRR). Bismuth has a certain electrocatalytic nitrogen reduction effect because of the strong force between the Bi 6p band and the N 2p orbital. The subsequent one-pot solvothermal method ensure the successful doping of Bi into the CeO2 structure, and the catalyst material Bi-CeO2 has sufficient adhesion with the substrate carbon paper, thereby ensuring electrode stability. Meanwhile, the introduction of a Bi atom to CeO2 is an effective strategy to increase the abundance of oxygen vacancies in CeO2 for the rate-determining step and hence better promote NRR activity compared with classic transition-metal catalysts because the electrons trapped by the oxygen vacancies present in the catalyst material can be injected into the counterbond orbitals of N-2 adsorbed on the catalyst material, thereby weakening the N N triple bond for later activation and hydrogenation. The catalyst achieves a high R-NH3 of 6.29 mu g h(-1) cm(-2) with a Faradaic efficiency (FE) of 8.56% at -0.5 V (vs RHE) in 0.5 M K2SO4 at room temperature. This Article provides a new avenue for the design and development of efficient catalysts for the electrocatalytic NRR.