Molecular anchoring induced charge transfer pathway conversion from p-n to S-scheme heterojunction for boosting photocatalytic hydrogen evolution and N2 fixation

Abstract

The p-n type charge transfer pathway plays an active role in efficient carrier separation and enhancement of photocatalytic activity, but also reduces the redox ability of photogenerated carriers. Herein, the anchored amino molecular layer can act as a heterojunction conversion switch to transform Cu2O/T-N from p-n to S-scheme heterojunction. Post-transformation, the redox ability of carriers can be dramatically enhanced: the reduction potential of photogenerated electrons is raised from -0.49 eV to -1.68 eV, and the oxidation potential of photogenerated holes is raised from 0.32 eV to 2.33 eV. Therefore, the optimized Cu2O/T-N S-scheme heterojunction photocatalyst achieves superior photocatalytic performance for hydrogen evolution (up to 41.85 mmol g-1, 64 times higher than pure titanium dioxide) and nitrogen fixation (as high as 18 mmol gCu2O-1 h-1). Moreover, the post-conversion carrier transfer pathway also prevents the accumulation of holes on Cu2O, alleviating the photocorrosion caused by hole oxidation. Hence the catalytic activity remained stable during photocatalytic cycling up to 50 h. This study provides a straightforward and practical method for enhancing the redox capacity of photocatalysts.