Heterogeneous doping via charge carrier transport improves Photoelectrochemical H2O oxidative H2O2 synthesis

Photoelectrochemical (PEC) water splitting into H2O2 and H2 has attracted significant attention due to its low cost and sustainability. However, slow charge carrier transport and water oxidation kinetics limit the selectivity for H2O2 production and solar conversion efficiency. Herein, we propose a heterogeneous doping approach that combines surface gradient doping with bulk doping to improve the charge carrier transport in the photo -electrode. Inducing gradient Nb and homogeneous Mo doping into BiVO4 photoanode (G-Nb/Mo:BVO) can promote charge separation and carrier transfer, leading to the high selectivity for H2O2 generation and sup-pression of O2 production. Consequently, the heterogeneously doped G-Nb/Mo:BVO photoanode presents an average Faraday efficiency (FE) of over 80% for H2O2 production in a wide potential of 0.6-1.8 VRHE with the maximum FE of 83.7% at 1.2 VRHE under AM 1.5G illumination. More importantly, H2O2 production rate can reach 1.23 mu mol min- 1 cm-2 at 1.23 VRHE, representing the best H2O2 production rate reported for the photo -electrodes. Density functional theory calculations prove that Mo and Nb co-doping increases the reactivity of BiVO4 and improves 2e- water oxidation reaction activity and selectivity. This work demonstrates that het-erogeneous doping provides a cost-effective strategy to break performance trade-offs by improving charge carrier separation and transport in light absorbers, and modulating the selectivity and activity of water oxidation re-action to generate H2O2, which can be extended to other photocatalytic reactions.

Automated summary

A heterogeneous doping approach, combining surface gradient doping with bulk doping, can enhance charge carrier transport and improve selectivity for H2O2 production in photoelectrochemical (PEC) water splitting. By inducing gradient Nb and homogeneous Mo doping into the BiVO4 photoanode, charge separation and carrier transfer are promoted, leading to high selectivity for H2O2 generation and suppress ion of O2 production.