Three-dimensional ordered macroporous g-C3N4-Cu2O-TiO2 heterojunction for enhanced hydrogen production

Abstract

In this study, a g-C 3 N 4 -Cu 2 O-TiO 2 photocatalyst with a novel three-dimensional ordered macroporous (3DOM) structure was successfully prepared using a sacrificial template strategy and a photodeposition method. The influence of the special porous structure with cross pore channels on the photocatalytic properties of the as-prepared sample was studied in detail. Compared with the original photocatalyst (TiO 2 with 3 wt% Pt), g-C 3 N 4 -Cu 2 O-TiO 2 exhibited a higher specific surface area and more active sites, thus accelerating the separation efficiency of the photogenerated electron-hole pair. Consequently, the as-prepared photocatalyst showed good photocatalytic performance, reaching a maximum hydrogen production rate of 12,108 µmol g −1 h −1 and approximately five times higher than that of the pristine comparison sample. The enhanced photoactivity of the g-C 3 N 4 -Cu 2 O-TiO 2 heterojunction can be ascribed to its double p-n heterojunction and robust porous structure, where the photodeposited Cu 2 O plays a synergistic catalytic role in the photocatalytic process and the outer clad g-C 3 N 4 layer prevents Cu 2 O oxidation. Additionally, the possible photocatalytic mechanism was briefly discussed based on the experimental results. This work identifies viable pathways for developing low-cost heterojunction photocatalysts with highly efficient photocatalytic activity toward improved solar energy conversion.

Enhanced photocatalytic hydrogen evolution and ammonia sensitivity of double-heterojunction g-C3N4/TiO2/CuO

“…The specific surface areas of g-C 3 N 4 /TiO 2 and CuO/TiO 2 are only 28.51 and 6.34 m 2 g −1 , respectively, while that of the g-C 3 N 4 /TiO 2 /CuO ternary catalyst is 3.38 m 2 g −1 and lower than those of the other two catalysts, as shown in Table 2, which is caused by the combination of CuO deposition and g-C 3 N 4 pore coverage. 16 As expected, the g-C 3 N 4 /TiO 2 /CuO catalyst also gives the lowest pore volume of 0.009 cm 3 g −1 , corresponding to a pore diameter of 10.71 nm, which is higher than those of the other two catalysts. A large aperture can increase the refractive index of incident light to improve the utilization of light.…”

“…15 As shown in preceding records, the band gap of TiO 2 was opportunely matched with the band gap of g-C 3 N 4 . 16 Combining TiO 2 with g-C 3 N 4 to produce a new composition can increase the flat plate potential and reduce the band gap of the composite. This is conducive to the electronic transition between heterogeneous interfaces.…”

In situ Cu single atoms anchoring on MOF-derived porous TiO2 for the efficient separation of photon-generated carriers and photocatalytic H2 evolution

“…It can be seen that the 0.75Cu-TiO 2 catalyst has a smaller arc radius, indicating that the presence of Cu single atoms helps to inhibit the recombination of EHPs, which is consistent with the PL and transient photocurrent response analyses. 48,49 Surface photovoltage (SPV) tests were also performed by Kelvin probe force microscopy. Since the signal strength of SPV is related to the number of separated photo-generated charge carriers and the transfer distance, the SPV signal is directly related to the separation of charge carrier space and the evolution of surface charges, which is more convincing compared with other techniques.…”

Oxide based Heterostructured Photocatalysts for CO2 Reduction and Hydrogen Generation

“…This improved photocatalytic performance was effectuated by the heterojunctions formed which facilitated the photo-induced charge carriers separation. In a study, g-C 3 N 4 -Cu 2 O-TiO 2 photocatalyst was synthesized by Chen et al [103] to investigate the photocatalytic efficiency towards hydrogen generation. The as synthesized photocatalyst turned out to be excellent photocatalytic system as it yielded hydrogen at 12.11 mmol g À 1 h À 1 evolution rate.…”