Photoanodic H2O2 synthesis and in-situ tetracycline degradation using transition-metal phosphide co-catalysts

Abstract

H2O2 as an essential chemical can be produced by photoanodic water oxidation reaction but is restricted by low production rate and poor selectivity. Herein, three kinds of transition metal phosphide, namely Fe2P, Co2P, and Ni5P4, have been loaded on Mo doped BiVO4 (MB) photoanodes to promote H2O2 production. Among them, the optimal performance has been achieved by Ni5P4/MB photoanode with the yield of 20.8 µmol h−1 cm−2 and the selectivity of 41.9 % at the applied voltage of 1.7 V (vs. RHE) under AM 1.5 G illumination. By loading Ni5P4 on MB, the production rate of OH• radicals and the desorption of the as-formed H2O2 have been promoted. The intermediates, OH• radicals, have been in-situ applied for tetracycline degradation, and Ni5P4/MB photoanode presents the best performance. This work has demonstrated the developments of metal phosphide as co-catalysts for photoanodic H2O2 production from water and meanwhile paved the pathway for its in-situ use in water disinfectant.