Oxygen Vacancies-Rich Metal Oxide for Electrocatalytic Nitrogen Cycle

The development of industry and agriculture has been accompanied by an artificially imbalanced nitrogen cycle, which threatens human health and ecological environments. Electrocatalytic systems have emerged as a sustainable way of converting nitrogen-containing molecules into high value-added chemicals. However, the construction of high-performance electrocatalysts remains challenging. The development of oxygen vacancy engineering strategy has promoted more research efforts to explore the structure-activity relationship between catalytic activity and oxygen vacancies. This review systematically summarizes the recent development of oxygen vacancies-rich metal oxides for electro-catalyzing nitrogen cycling systems, involving electrocatalytic nitrate reduction reaction, nitric oxide reduction reaction, nitrogen reduction reaction, CN coupling, urea oxidation reaction, and nitrogen oxidation reaction. First, the construction methods and characterization methods of oxygen vacancies are summarized. Then, the effect of oxygen vacancy on electrocatalytic activity of metal oxides is discussed in terms of regulating the electronic structures of electrocatalysts, improving the electroconductivity of catalysts, lowing the energy barrier, and strengthening adsorption and activation of intermediate species. Finally, future directions for oxygen vacancy engineering and electrocatalytic nitrogen cycle are anticipated. The applications of oxygen vacancy (Ov)-rich metal oxides in the reactions related to the electrocatalytic nitrogen cycle are reviewed, involving the nitrate reduction reaction, nitric oxide reduction reaction, nitrogen reduction reaction, C-N coupling reaction, urea oxidation reaction and nitrogen oxidation reaction. Ov engineering promotes the activity and stability of metal oxides by optimizing the adsorption of reactants and pivotal intermediate species.image