Heterogeneous doping via charge carrier transport improves Photoelectrochemical H2O oxidative H2O2 synthesis
Jinwei Bai, Rui‐Ting Gao, Nhat Truong Nguyen, Xianhu Liu, Xueyuan Zhang, Lei Wang
Abstract
Photoelectrochemical (PEC) water splitting into H 2 O 2 and H 2 has attracted significant attention due to its low cost and sustainability. However, slow charge carrier transport and water oxidation kinetics limit the selectivity for H 2 O 2 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 photoelectrode. Inducing gradient Nb and homogeneous Mo doping into BiVO 4 photoanode (G-Nb/Mo:BVO) can promote charge separation and carrier transfer, leading to the high selectivity for H 2 O 2 generation and suppression of O 2 production. Consequently, the heterogeneously doped G-Nb/Mo:BVO photoanode presents an average Faraday efficiency (FE) of over 80% for H 2 O 2 production in a wide potential of 0.6–1.8 V RHE with the maximum FE of 83.7% at 1.2 V RHE under AM 1.5G illumination. More importantly, H 2 O 2 production rate can reach 1.23 μmol min −1 cm −2 at 1.23 V RHE , representing the best H 2 O 2 production rate reported for the photoelectrodes. Density functional theory calculations prove that Mo and Nb co-doping increases the reactivity of BiVO 4 and improves 2e − water oxidation reaction activity and selectivity. This work demonstrates that heterogeneous 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 reaction to generate H 2 O 2 , which can be extended to other photocatalytic reactions.