No abstract

Mesoporous TiO2 has gained increasing interest because of its outstanding properties and promising applications in a wide range of fields. Herein, we report the facile synthesis of ordered mesoporous black TiO2 (OMBT) materials, which exhibit excellent photocatalytic hydrogen evolution performances. In this case, the employment of a thermally stable and high-surface-area mesoporous TiO2 as the hydrogenation precursor is the key for fabricating the OMBT materials, which not only facilitate H2 gas diffusion into TiO2 and interaction with their structures but also maintain the ordered mesoporous structures as well as inhibit the phase transformation (from anatase to rutile) and crystal growth during hydrogenation at 500 °C. The resultant OMBT materials possess a relatively high surface area of ∼124 m(2) g(-1) and a large pore size and pore volume of ∼9.6 nm and 0.24 cm(3) g(-1), respectively. More importantly, the OMBT materials can extend the photoresponse from ultraviolet to visible and infrared light regions and exhibit a high solar-driven hydrogen production rate (136.2 μmol h(-1)), which is almost two times as high as that of pristine mesoporous TiO2 (76.6 μmol h(-1)).

Phosphorus-doped hexagonal tubular carbon nitride (P-TCN) with the layered stacking structure was obtained from a hexagonal rod-like single crystal supramolecular precursor (monoclinic, C2/m). The production process of P-TCN involves two steps: 1) the precursor was prepared by self-assembly of melamine with cyanuric acid from in situ hydrolysis of melamine under phosphorous acid-assisted hydrothermal conditions; 2) the pyrolysis was initiated at the center of precursor under heating, thus giving the hexagonal P-TCN. The tubular structure favors the enhancement of light scattering and active sites. Meanwhile, the introduction of phosphorus leads to a narrow band gap and increased electric conductivity. Thus, the P-TCN exhibited a high hydrogen evolution rate of 67 μmol h(-1) (0.1 g catalyst, λ >420 nm) in the presence of sacrificial agents, and an apparent quantum efficiency of 5.68 % at 420 nm, which is better than most of bulk g-C3 N4 reported.