Visible light-driven photoelectrocatalytic degradation of tetracycline on NiFe2O4/SiNWs heterojunction

Silicon nanowires (SiNWs), with their simple fabrication process and large surface area, show promise as photoelectric materials. However, their limited charge separation efficiency and light absorption properties hinder its further development. Therefore, it is necessary and meaningful to improve its performance by cocatalyst modification. Herein, NiFe2O4/SiNWs heterojunctions were successfully synthesized by an efficient and convenient spin-coating method, and a photoelectrocatalytic degradation system based on NiFe2O4/SiNWs heterojunction was constructed for the degradation of TC under the conditions of simulated light and applied voltage. UV-NIR, LSV and EIS experimental results demonstrate that the composite exhibits higher light absorption, stronger photocurrent density, and lower carrier recombination, resulting in significantly enhanced photoelectrocatalytic activity. Consequently, NiFe2O4/SiNWs heterojunction as the photoelectrocatalyst achieved a TC degradation rate of 90.24 % with a kinetic constant (k) of 0.01202 min-1, which was 4.73 and 10.27 times higher than those for pure SiNWs under identical conditions. Further experimental and theoretical results confirmed that the center dot OH provided by NiFe2O4 as a co-catalyst played a dominant role in the degradation process, which significantly improved the degradation efficiency of TC by SiNWs. This work confirms the synergistic catalytic effect between NiFe2O4 and SiNWs, opening up new possibilities for exploring composite photoanodes with diverse co-catalysts for antibiotic wastewater treatment.