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 H 2 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-C 3 N 4 nanotube@polydopamine(pDA)/NiCo-LDH (LPC) composite photocatalyst by combining hydrothermal and calcination method. In the LPC composite system, the one-dimensional (1D) g-C 3 N 4 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-C 3 N 4 /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 H 2 evolution compared with the g-C 3 N 4 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-C 3 N 4 @pDA/NiCo-LDH composite photocatalyst displays the potential practical application in the field of energy conversion.