Bifunctional Nitrogen-Doped Carbon Dots in g-C<sub>3</sub>N<sub>4</sub>/WO<sub><i>x</i></sub> Heterojunction for Enhanced Photocatalytic Water-Splitting Performance
Tong Song, Xiao Zhang, Ping Yang
Abstract
A novel metal-free all-solid-state z-scheme g-C3N4/NCDs/WOx 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–1 h–1, which increased to roughly seven times higher than that of pure g-C3N4 and roughly twice that of g-C3N4/NCDs or g-C3N4/WOx binary heterojunctions. The apparent quantum efficiency is 7.58% at 420 nm. The localized surface plasmon resonance effect of WOx and the up-converted photoluminescence property of NCDs enhanced the utilization efficiency of NIR light together. In addition, the matched energy band structures of WOx and g-C3N4 as well as the effective electron conductor (NCDs) between them accelerate electron transfer at the interface. The all-solid-state z-scheme g-C3N4/NCDs/WOx 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.