3D HCN nanotexture with synergistic effect of nickel and hole scavengers for enhancing photocatalytic H2 production: Role of morphology and influential parameters

Abstract

• 3D porous graphic carbon nitride was fabricated using facile hydrothermal approach. • Higher porous structure with faster charge carrier separation was observed in 3D structure. • Using 3D Ni/HCN, significantly higher H 2 was obtained compared to bulk g-C 3 N 4 . • Using methanol, much higher H 2 yield was obtained than ethanol, glycerol and TEOA. • Catalyst loading, feed concentration and sacrificial reagents greatly affect activity and stability. Well-designed three-dimensional (3D) nanotextures of graphitic carbon nitride (g-C 3 N 4 ), synthesized using template free single step method and mediated with nickel as a noble free metal, for solar hydrogen production, has been investigated. The photoactivity was investigated in a slurry type continuous flow photoreactor system by using different influential parameters such as hole scavengers, diffusion effects, time, and mass transfer. Compared to bulk g-C 3 N 4 , H 2 yield was increased with 3D hierarchical carbon nitride (HCN) nanotexture. The H 2 evolution rate was reached to 1310 µmol g −1 h −1 with optimized 2 % Ni loading to 3D HCN. This H 2 evolution rate was 19.8 and 24.9 times higher than it was generated using 3D HCN and g-C 3 N 4 , respectively. The special interlayer opening, more light penetration and suppressed charge carrier recombination were the main contributors for this photoactivity enhancement. Among the different influential parameters, lower viscosity, higher number of protons and less diffusion effects were promising to give significantly higher H 2 production. The stability of nanotextures was entirely dependent on the attached reactants over the nickel reactive sites, which was more promising for Triethanolamine (TEOA) than using methanol. This newly developed low-cost 3D HCN can be promising in solar energy conversion and other energy applications.