Chlorophyll sensitized BiVO4 as photoanode for solar water splitting and CO2 conversion

Converting solar energy into valuable hydrogen and hydrocarbon fuels through photoelectrocatalytic water splitting and CO2 reduction is highly promising in addressing the growing demand for renewable and clean energy resources. However, the solar-to-fuel conversion efficiency is still very low due to limited light absorption and rapid bulk recombination of charge carriers. In this work, we present chlorophyll (Chl) and its derivative sodium copper chlorophyllin (ChlCuNa), as dye sensitizers, modified BiVO4 to improve the photoelectrochemical (PEC) performance. The photocurrent of BiVO4 is surprisingly decreased after a direct sensitization of Chl while the sensitization of ChlCuNa obviously enhances photocurrent of BiVO4 electrodes by improved surface hydrophilicity and extended light absorption. ChICuNa-sensitized BiVO4 achieves an improved H-2 evolution rate of 5.43 p,mol h(-1) cm(-2) in water splitting and an enhanced HCOOH production rate of 2.15 mu mol h(-1) cm(-2) in CO2 PEC reduction, which are 1.9 times and 2.4 times higher than pristine BiVO4, respectively. It is suggested that the derivative ChiCuNa is a more effective sensitizer for solar-to-fuel energy conversion and CO2 utilization than Chl. (C) 2017 Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences. Published by Elsevier B.V. All rights reserved.