Boosting nitrate removal efficiency via synergistic strategy: Oxygen vacancy engineering and morphological control

The nitrate reduction reaction (NO₃^-RR) is a promising strategy for groundwater remediation. However, the development of electrocatalysts with high performance and low energy consumption remains a significant challenge. Here, we developed a new method with a dual modulation strategy involving vacancy engineering and morphology modulation engineering to synthesize rough surface nanospheres (c-Fe₂O₃) enriched with oxygen vacancies. The c-Fe₂O₃ exhibits excellent catalytic performance, with a Faraday efficiency of up to 95.54 %. More importantly, this electrocatalyst simultaneously achieves high performance and low energy consumption (EC = 0.35 kWh/mol, E_EO = 1.40 kWh/m³) in under low concentration. Theoretical research verify that morphology modulation enriches the reaction substrate and improves the active site utilization efficiency. Moreover, in addition to optimizing the electronic structure of Fe₂O₃ and improving the charge transfer efficiency, the presence of oxygen vacancies (O_v) provides active sites that enhance the adsorption and dissociation of NO₃^- and reduce the energy barrier of the reaction step. This study develops a new method for preparing electrode materials that exhibit low energy consumption and high performance through a dual modulation strategy involving morphological regulation and vacancy engineering. The developed strategy also provides a broader technical route for the activity enhancement of other metal oxide catalysts.