Tuning of internal electric field and diffusion distance boosting the charge separation for photocatalytic electricity generation

Abstract

Solar-light driven electricity generation from organic molecule oxidation emerges as a green technology for energy conversion and sewage recycling. However, low charge separation efficiency severely restricts the photocatalytic electricity generation and photooxidation. Herein, we introduce a novel monolayered Sb-BiOCl nanosheets fabricated via injecting Sb ions and hydrophobic chains of cetyltrimethylammonium (CTA+) for photocatalytic electricity generation. By visible light irradiation and addition of organic molecule fuel to artificially construct the photo fuel cell system, the BiOCl with 10% Sb dopant converts electricity with 3.9-fold increase compared to the bulk BiOCl. The enhanced electrical output is primarily attributed to their efficient charge separation facilitated by the boosted internal electric field (IEF) and reduced diffusion distance. DFT calculation and electrochemical test demonstrate that the nonuniform charge distribution between [Bi2O2] and [Cl] slices resulting from the electron donor Sb doping contributes to 92-fold increase of IEF parallel to [010] zone. Significantly, the shortened transport channel of charge carriers further promotes the photogenerated charge anisotropic separation. This work proves that the cooperative effect of IEF and diffusion distance tuning can boost the charge separation of photocatalysts, which offers a useful strategy for constructing effective solar-light driven electricity generation system.