Polyoxometalates acting as a hole-transfer mediator and crystallization accelerant in a perovskite photoanode for the photoelectrocatalytic oxidation of benzene into phenol.

Abstract

Organic metal halide perovskite (OMHP) material shows promising applications in the photoelectrocatalytic field, but its efficiencies are unsatisfactory due to the bulk and surface carrier recombination. In this work, we used dual polyoxometalates (C4H9N)3PW12O40 and [Ag10[{Co(H2O)3}2{CoBi2W19O66(OH)4}] to modify the OMHP photoanode; the former acted to improve the quality of the perovskite film and the latter could facilitate hole transfer. Such dual modifications effectively reduce carrier recombination and thus obviously boost photoelectrocatalytic efficiency. Hence, we explored the photoelectrocatalytic oxidation of benzene into phenol in aqueous solution by using the modified OMHP photoanode. The yield of phenol in the reaction using the modified OMHP photoanode reached about 31.8%, which was obviously superior to that using the pure OMHP photoanode. Furthermore, we carried out radical scavenger studies to investigate the active species involved in the photoelectrocatalytic benzene oxidation reaction, and thus proposed the plausible mechanism of the photoelectrocatalytic oxidation of benzene into phenol over the OMHP photoanode. These results provide new insights into the development of high performance OMHP photoanodes for photoelectrocatalytic organic transformation.