Forming TiO₂ mesoporous microspheres with small particle size and can provide abundant active sites for photocatalytic hydrogen production due to their high surface area and mesoporous structure. In addition, graphene is selected as a co-catalyst for photocatalytic hydrogen production due to the excellent conductivity and high specific surface area of graphene materials, which has excellent enrichment effect on photogenerated electrons of the photocatalyst and can effectively inhibit the recombination of photogenerated carriers and improve the photocatalytic hydrogen production activity.

Abstract

The regulation of surface active sites and structures is a key factor affecting the performance of photocatalysts. In order to prepare monodisperse anatase TiO₂ mesoporous microspheres with higher specific surface area, smaller pore size and particle size, a dual-surfactant orientation assembly method was selected. Graphene (NG) was selected as a cocatalyst to compound with mesoporous TiO₂ and nickel doping was performed on the cocatalyst to improve the photocatalytic hydrogen production activity of the semiconductor photocatalyst. Through proper regulation and rational design, the semiconductor photocatalyst with desired properties was prepared. SEM characterization of mesoporous titanium dioxide (TiO₂/Ni-NG) with graphene cocatalyst proved that TiO₂ nanospheres have good monodispersion, and TiO₂ nanospheres are well supported on graphene cocatalyst. The composite material belonged to mesoporous group with the pore size being mainly distributed between 10–20 nm. The loading of graphene and Ni-NG cocatalyst increased the absorption band edge by 9 nm and 38 nm, respectively, and the band gap decreased by 0.07 eV and 0.16 eV, respectively. The selection of graphene as cocatalyst improved the hydrogen production activity of photocatalyst and nickel doping was very effective in the modification of graphene. For reaction time of 2.5 h, the H₂ production of TiO₂/Ni-NG material reached 1.767 mmol/g which was 7.27 times that of TiO₂/NG composite material.