Band alignment of homojunction by anchoring CN quantum dots on g-C3N4 (0D/2D) enhance photocatalytic hydrogen peroxide evolution

Polymeric carbon nitride (C3N4) is a very attractive candidate to produce photocatalytic hydrogen peroxide (H2O2) due to its low-cost, metal-free characteristics. However, the low efficiency would limit its development to higher yields because of insufficient light absorption and electron-hole separation. Here, we developed a simple method to anchor CN quantum dots (QDs) onto g-C3N4 nanosheets to form a homojunction structure (HJ-C3N4), which could improve photocatalytic performance largely without introducing metal elements. Its superior efficiency is a result of the band alignment by the homojunction structure providing excellent electron-hole separation and QDs providing suppressed recombination. Simultaneously, the light responsiveness of QDs endows a wide spectrum-responsive adsorption and enhances the adsorption intensity. The H2O2 yield of the HJ-C3N4 reached 115 mu mol L-1 h(-1) in pure water by visible light, which has an 8.6x higher production than g-C3N4 nanosheets. The material design of 0D/2D homojunction could be extended to other materials with specific band alignment.

Automated summary

The homojunction structure of anchoring CN quantum dots (QDs) onto g-C3N4 nanosheets resulted in a significantly improved photocatalytic efficiency for producing hydrogen peroxide (H2O2). The band alignment and electron-hole separation provided by the homojunction structure, along with the suppressed recombination from QDs, contributed to the enhanced performance. This design could be extended to other materials with specific band alignment for further applications.