Photoelectrochemical Degradation of Organic Pollutants Using BiOBr Anode Coupled with Simultaneous CO2 Reduction to Liquid Fuels via CuO Cathode

This study develops a novel system consisting of BiOBr as a photoanode and CuO as photocathode for coupling photoelectrocatalytic (PEC) oxidation of tetracycline (TC) with photoelectrocatalytic reduction of CO 2 to form useful chemicals, such as CH 3 OH and CH 3 CH 2 OH. Under illumination, the degradation efficiency of TC was compared using photoelectrocatalytic (PEC), photocatalysis (PC), and electrocatalysis (EC) after 2.5 h. About 80% of TC was removed in the PEC process against 39% and 63% removed in PC and EC processes, respectively, and the kinetic constants of them are estimated to be 0.418, 0.211, and 0.286 h –1, respectively. Apparently, the results show the system of PEC has a synergistic effect between PC and EC for the degradation of TC. Furthermore, the onset potential of the total current was approximately −0.6 V (vs AgCl/Ag), and the yield of CH 3 OH and C 2 H 5 OH is the best at the bias potential of −0.7 V. And the yield of CH 3 OH and C 2 H 5 OH was 125.9 and 26.5 μmol/L, respectively. Results of UV–vis absorption spectra, total organic carbon, liquid chromatography-mass spectra, nuclear magnetic resonance, and in situ IR confirm the carbons change from organic pollutants to CO 2 and then to liquid fuels. Finally, we proposed a catalytic mechanism to explain the synergetic effect of PEC oxidation and PEC reduction and the synergetic effect of PC and EC. The present work provides a new avenue to achieve the one-pot conversion of organic pollutants to liquid fuels and puts forward a new idea to couple PEC oxidation and PEC reduction.