High efficiency for H2 evolution and NO removal over the Ag nanoparticles bridged g-C3N4 and WS2 heterojunction photocatalysts

Ag nanoparticles bridged g-C3N4 and WS2 nanosheets heterojunction (x-y-WAC) and Ag nanoparticles deposited g-C3N4/WS2 heterojunction (x-y-AWCA) were prepared through a solvent evaporation and high temperature calcinations method, the x is the percentage of Ag nanoparticles and y is WS2 nanosheets in mass fraction, respectively. The as-prepared heterojunctions were applied to water splitting for H-2 evolution and NO removal at the indoor air level under simulated sunlight irradiation, in which the H-2 production rate and NO removal efficiency of the bridged structure are much higher than that of deposited structure. The H-2 production rate of most effective samples (2-20-WAC) were measured to be 68.62 mu molh(-1), which are 1.86 and 15.67 times higher than that of pure g-C3N4 and WS2 nanosheets, respectively. The gradient test of Ag nanoparticles and WS2 nanosheets indicated that the optimum amounts of Ag nanoparticles and WS2 nanosheets were 2% and 20% in mass fraction. The morphology of 2-20-WAC heterojunction was characterized by SEM, TEM and HRTEM techniques and the results revealed that the Ag nanoparticles were intercalated into the interlayer of g-C3N4 and WS2 nanosheets. According to the XRD, FT-IR, UV-vis and XPS analysis, the Ag nanoparticles, g-C3N4 and WS2 nanosheets are hybrid by chemical bond through the second calcinations. Furthermore, the bridged structure can promote the separation rate of charge carriers and suppress the recombination of them at the same time, which could be deduced from photocurrent and PL investigation. Based on the characterization and results analysis, it can be inferred that the bridged structure can accelerate the transport of charge carriers and restrain the recombination of electrons and holes at the same time, which could improve photocatalytic performance of the heterojunction. (C) 2017 Elsevier B.V. All rights reserved.