Titanium carbide-functionalized cobalt selenide as a heterogeneous electro-Fenton cathode catalyst for the degradation of sulfamerazine

In the heterogeneous electro-Fenton (Hetero-EF) process, the generation and activation efficiency of hydrogen peroxide (H₂O₂) is an important factor affecting the performance. Based on ability of Mxene to regulate charge density at metal active sites and enhance electronic transport efficiency, a nanoflower-shaped CoSe and plateshaped Ti₃C₂ composite (CoSe/Ti₃C₂) was developed for use as a Hetero-EF cathode catalyst. The results showed that CoSe/Ti₃C₂ had excellent degradation performance, with a sulfamerazine (SMR) (10 mg·L^-1) degradation efficiency of 100% within 80 min in the pH range of 3–7. CoSe/Ti₃C₂ (n = 2.59) had a lower transfer electron number compared to that of CoSe (n = 3.21) and was more inclined towards 2e-ORR. Theoretical calculations showed that Ti₃C₂ regulated the d-band center of CoSe, weakening adsorption strength of Co sites for the *OOH intermediate and making it more inclined to generate H₂O₂. Electron paramagnetic resonance (EPR) and quenching experiments indicated the presence of •OH, •O₂^-, and ¹O₂ in the system, all of which participated in the degradation of pollutants. The construction of a multi reactive oxygen species system enhanced the interference resistance during degradation.