Laser flash photolysis study of NbO/g-CN heterostructures as efficient photocatalyst for molecular H evolution.

Improvements of visible light activity, slow recombination rate, stability, and efficiency are major challenges facing photocatalyst technologies today. Utilizing heterostructures of g-CN (bandgap ∼2.7eV) with NbO (bandgap ∼3.4eV) as an alternative materials for the first time, we tried to overcome such challenges in this work. Heterostructures of NbO/g-CN have been synthesized via hydrothermal technique. And then a time-resolved laser flash photolysis of those heterostructures has been analyzed, focusing on seeking how to improve photocatalytic efficiency for molecular hydrogen (H) evolution. The transient absorption spectra and the lifetime of charge carriers at different wavelengths have been observed for NbO/g-CN, where g-CN was used for a control. The role of hole scavenger (methanol) has also been investigated for the purpose of boosting charge trapping and H evolution. The long lifetime of NbO/g-CN heterostructures (6.54165 μs) compared to g-CN (3.1651897 μs) has successfully supported the increased H evolution of 75 mmol/h.g. An enhancement in the rate of H evolution (160 mmol/h.g) in the presence of methanol has been confirmed. This study not only deepens our understanding of the role of scavenger, but also enables a rigorous quantification of the recombination rate crucial for photocatalytic applications in relation with efficient H production.