Constructing N-Doped KNb 3 O 8 /g-C 3 N 4 Composite for Efficient Photocatalytic H 2 Generation and Degradation under Visible Light Irradiation

To improve the light harvesting ability and photogenerated carriers separation, N-doped KNb 3 O 8 supported graphitic carbon nitride (g-C 3 N 4 ) was prepared by a facile calcination method using nitrogen-rich precursor of melamine for the first time. The electric structure of KNb 3 O 8 layers was well regulated by N doping to achieve visible light response. Simultaneously, the formed g-C 3 N 4 was combined with N-doped KNb 3 O 8 to gain heterojunction structure. The separation, transfer and recombination processes of photogenerated charge carriers were investigated by transient photocurrent, electrochemical impedance spectra (EIS) and photoluminescence (PL) measurement. The photocatalytic performances were evaluated by H 2 generation and RhB degradation under visible light irradiation. The sample of N-doped KNb 3 O 8 /g-C 3 N 4 (KNCN) exhibited the high photocatalytic performance for H 2 generation and RhB degradation, which is mainly attributed to the synergistic effects of the extended light harvesting ability and effective charge transportation/separation rate by N-doping and heterojunction formation, respectively. A possible mechanism for the photocatalytic degradation of RhB was proposed. Graphic Abstract A composite photocatalyst of N-doped KNb 3 O 8 supported g-C 3 N 4 exhibited the significant enhancement on photocatalytic performance for both H 2 generation and RhB degradation, which is mainly attributed to the synergistic effects of the extended light harvesting ability and effective charge transportation/separation rate by N-doping and heterojunction formation, respectively.