Synergetic activation of H2O2 by photo-generated electrons and cathodic Fenton reaction for enhanced self-driven photoelectrocatalytic degradation of organic pollutants

In this work, a self-driven photocatalytic fuel cell (PFC) system was constructed, which consisted of a noble metal-free Cu 2 O/CuO photocathode and a semi-transparent BiVO 4 photoanode. The proposed PFC system was used for the degradation of phenol and the removal efficiency of phenol using BiVO 4 -Cu 2 O/CuO system was higher than the PFC using Pt cathode (BiVO 4 -Pt, 67.3%) and bare Cu 2 O cathode (BiVO 4 -Cu 2 O, 84.6%). The short circuit photocurrent of the BiVO 4 - Cu 2 O/CuO system was 0.30 mA cm −2 , which was higher than the sum of photocurrents generated by the other two photoelectrodes. This could be attributed to the self-driven bias induced by the good match of Fermi levels (E F s) between the BiVO 4 and the heterojunction Cu 2 O/CuO electrode. The addition of 5 mM H 2 O 2 to the PFC system greatly enhanced the degradation process, with the pseudo-first-order kinetic rate constant increased from 0.136 to 2.568 h -1 after the addition of H 2 O 2 . Compared with traditional Fenton and Cu-based Fenton-like process, the PFC-H 2 O 2 system has advantages of the broad working pH range (4–7), zero formation of ferric hydroxide sludge and less copper leaching. The X-ray photoelectron spectroscopy (XPS) analysis confirmed the cycle between Cu(I) and Cu(II) on the surface of Cu 2 O/CuO photocathode, indicating that a Fenton-like reaction had occurred on Cu 2 O/CuO photocathode. The H 2 O 2 was activated by both the photo-generated electrons and the Cu 2 O/CuO cathode, which further increased the degradation efficiency of phenol. Furthermore, a high stability was exhibited by the H 2 O 2 -PFC system.