Bifunctional Nitrogen-Doped Carbon Dots in g-CN/WO Heterojunction for Enhanced Photocatalytic Water-Splitting Performance.

A novel metal-free all-solid-state z-scheme g-CN/NCDs/WO photocatalyst was fabricated using nitrogen-doped carbon dots (NCDs) as the electron mediator. As-prepared sandwich-structured composites displayed enhanced visible and NIR light photocatalytic activity. Under visible light irradiation, the hydrogen evolution rate reached 3.27 mmol g h, which increased to roughly seven times higher than that of pure g-CN and roughly twice that of g-CN/NCDs or g-CN/WO binary heterojunctions. The apparent quantum efficiency is 7.58% at 420 nm. The localized surface plasmon resonance effect of WO and the up-converted photoluminescence property of NCDs enhanced the utilization efficiency of NIR light together. In addition, the matched energy band structures of WO and g-CN as well as the effective electron conductor (NCDs) between them accelerate electron transfer at the interface. The all-solid-state z-scheme g-CN/NCDs/WO photocatlyst was confirmed by a series of characterizations and experiment results. This report offered new insights into constructing an efficient all-solid-state z-scheme photocatalyst to be applied during the photocatalytic water-splitting reaction in the visible and NIR light regions.