Efficient visible-light photocatalytic heterojunctions formed by coupling plasmonic Cu2-xSe and graphitic carbon nitride

Photocatalytic semiconductors have attracted considerable attention due to their applications in the degradation of organic pollutants. However, the low solar-light harvesting and high electron-hole recombination rate limit the efficiency of photocatalysts. The newly developed localized surface plasmon resonance (LSPR) can offer a new opportunity to overcome the limited efficiency to some extent. In this study, heterojunctions (Cu2-xSe-g-C3N4) incorporating plasmonic semiconductor Cu2-xSe with graphitic carbon nitride (g-C3N4) are proposed as visible light photocatalysts. Their photocatalytic performance is tested and proven via the degradation of methyl blue (MB) in an aqueous solution. When the mass percentage composition of Cu2-xSe reached 60%, the as-prepared composite exhibited the highest photocatalytic activity, which was almost 6.1 and 2.8 times as high as that of individual Cu2-xSe and g-C3N4, respectively. The remarkable photocatalytic efficiency of such Cu2-xSe-g-C3N4 heterojunctions under visible light illumination due to both plasmonic enhancement of the catalyst and synergetic effect of the co-catalyst is shown. This work can provide a new methodology to develop stable and highly efficient heterojunction photocatalysts.