Enhanced photocatalytic degradation and H_(2) evolution performance of N-CDs/S-C_(3)N_(4)S-scheme heterojunction constructed byπ-πconjugate 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-C_(3)N_(4))semiconductor throughπ-πconjugate interaction.Based on this,a novel 0D/2D S-scheme heterojunction N-CDs/S-C_(3)N_(4)hybrid was successfully prepared.The degradation kinetic constants of N-CDs/S-C_(3)N_(4)for rhodamine B(RhB)and p-nitrophenol(PNP)reached 0.23522 and 0.01342 min^(−1),repectively,which were 2.72 and 2.65 times that of S-C_(3)N_(4).The highest photocatalytic hydrogen evolution rate was observed under the simulated sunlight irradiation,which was 2.30 times that of S-C_(3)N_(4).The improvement of photocatalytic performance was mainly based on the formation of the S-scheme heterojunction between S-C_(3)N_(4)and N-CDs.The effects of internal electric field,π-πconjugate 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•O_(2)−,therefore the photocatalytic degradation and hydrogen evolution performance were significantly enhanced.