Double Z-scheme photocatalyst C3N4 nanotube/N-doped carbon dots/Ni2P with enhanced visible-light photocatalytic activity for hydrogen generation

Photocatalyst with double Z-scheme mechanism can promote the separation and transmission of photo-induced carriers effectively. In this work, a novel C3N4 nanotube (CNT)/N-doped carbon dots (NCDs)/Ni2P composite photocatalyst was prepared by decorating NCDs and Ni2P nanoparticles on CNT, respectively. A variety of test results, including photoluminescence spectra (PL), electrochemical impedance spectrum (EIS) and transient photocurrent responses (TPR), show that compared with CNT and CNT/Ni2P, CNT/NCDs/Ni2P composite can dramatically facilitate the separation and transmission of charge. Impressively, the CNT/NCDs/Ni2P composite achieves a hydrogen evolution rate of 627.2 mu mol g(-1) h(-1) which is well above that of CNT and CNT/Ni2P, respectively (no detection and 48.5 mu mol g(-1) h(-1)). Combining the above characterization results with energy band calculation, we speculate that the remarkably optimized photocatalytic activity was predominantly ascribed to the double Z-scheme charge transfer mechanism for CNT/NCDs/Ni2P nanocomposite. This work provides a new member for family of photocatalysts with double Z-scheme mechanism, which is beneficial to further fundamental and applied research.