Enhanced photocatalytic degradation and H2 evolution performance of N-CDs/S-C3N4 S-scheme heterojunction constructed by π-π conjugate self-assembly

Constructing heterojunction between two semiconductors with matched energy band structure is an effective modification method to obtain excellent photocatalysts. The experimental scheme adopts a simple solvent method to self-assemble nitrogen doped carbon dots (N-CDs) on the surface of sulfur doped carbon nitride (S-C3N4) semiconductor through pi-pi conjugate interaction. Based on this, a novel 0D/2D S-scheme heterojunction N CDS/S-C3N4 hybrid was successfully prepared. The degradation kinetic constants of N-CDs/S-C3N4 for rhodamine B (RhB) and p-nitrophenol (PNP) reached 0.23522 and 0.01342 min(-1), respectively, which were 2.72 and 2.65 times that of S-C3N4. The highest photocatalytic hydrogen evolution rate was observed under the simulated sunlight irradiation, which was 2.30 times that of S-C3N4. The improvement of photocatalytic performance was mainly based on the formation of the S-scheme heterojunction between S-C3N4 and N-CDs. The effects of internal electric field, pi-pi conjugate interaction and band bending promoted the photogenerated h(+) and e(-) with low redox ability to recombine and retained the beneficial h(+) and e(-) with strong redox ability, which contributed to the production of more active species of h(+) and center dot O-2(-), therefore the photocatalytic degradation and hydrogen evolution performance were significantly enhanced. (C) 2022 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.