Biomimetic design and synthesis of visible-light-driven g-C3N4 nanotube @polydopamine/NiCo-layered double hydroxides composite photocatalysts for improved photocatalytic hydrogen evolution activity

In the practical process of photocatalytic H2 evolution, optimizing the ability of light absorption and charge spatial separation is the top priority for improving the photocatalytic performance. In this study, we elaborately engineer neoteric g-C3N4 [email protected](pDA)/NiCo-LDH (LPC) composite photocatalyst by combining hydrothermal and calcination method. In the LPC composite system, the one-dimensional (1D) g-C3N4 nanotubes with larger specific surface area can afford more active sites and conduce to shorten the charge migration distance, as well as the high-speed mass transfer in the nanotube can accelerate the reaction course. The g-C3N4/NiCo-LDH type-II heterojunction can efficaciously stimulate the spatial separation of photo-produced charge. In addition, pDA as heterojunction metal-free interface mediums can provide multiple action (π-π* electron delocalization effect, adhesive action and photosensitization). The optimized LPC nanocomposite displays about 3.3-fold high photoactivity for H2 evolution compared with the g-C3N4 nanotube under solar light irradiation. In addition, the cycle experiment result shows that the LPC composite photocatalyst possesses superior stability and recyclability. The resultant g-C3N4@pDA/NiCo-LDH composite photocatalyst displays the potential practical application in the field of energy conversion.