NiFe-Based Electrocatalysts for Electrochemical Reduction of Selenite

Selenite, a common oxyanion pollutant in water, poses a significant threat to human health due to its bioaccumulation through the food chain. This study explores the viability of direct electrochemical reduction as an effective method for selenite removal, with a particular focus on the affordable Ni-based electrocatalyst materials. Among several Ni-based electrocatalysts, NiFe emerges as a superior material, demonstrating excellent selenite removal performance (82.6%) and Faradaic efficiency (57.3%) compared to gold (52.7% and 31.4%, respectively), a benchmark electrocatalyst for selenite removal reported in literature. Notably, NiFe exhibits substantially lower energy consumption (5.1 kWh per kg selenite removal) than goal (9.0 kWh per kg selenite removal). Environmental conditions, including the selenite concentration, temperature, and the presence of other oxyanions, are systematically investigated. Negligible impacts from nitrate and sulfate are observed. Elevating temperature significantly enhances selenite removal, with no adverse impact on Faradaic efficiency. Electrochemical active surface area analysis, supported by SEM figures, confirms the stability of NiFe during the selenite removal process. This study establishes NiFe as a robust and cost-effective electrocatalyst for the direct electrochemical reduction of selenite, offering promising prospects for addressing selenite contamination in water.