In Situ Microwave-Assisted Synthesis of Porous N-TiO₂/g-C₃N₄Heterojunctions with Enhanced Visible-Light Photocatalytic Properties

Abstract

An in situ microwave-assisted synthesis approach has been developed to prepare N-TiO2/g-C3N4 composites using H2TiO3 as the reactant and NH3·H2O as the N-doping source. In this way, the N-TiO2/g-C3N4 composite catalysts have a porous structure and large surface areas, which increase the contact area of pollutants. Degradation of rhodamine B (Rh B) and methylene blue (MB) were carried out to evaluate the photocatalytic activity of samples under visible light irradiation. N-TiO2/g-C3N4 composite with 40 wt % N-TiO2 exhibits the highest photocatalytic activity and the optimal temperature is 400 °C. The increased photocatalytic activity of N-TiO2/g-C3N4 composites can be attributed to the formation of the heterojunction between N-TiO2 and g-C3N4, which suppresses the recombination of photoinduced electron–hole pairs. The tests of radical scavengers confirmed that •O2 – was the main reactive species during the photocatalytic process.

Fabrication, characterization, and photocatalytic performance of exfoliated g-C3N4–TiO2 hybrids

“…However, a small shift around 0.3 eV toward low binding energy region was found for both Ti 2p 3/2 and Ti 2p 1/2 after hybridization of TiO 2 with CNs, which is possibly due to the partial substitution of Ti O with Ti N and resultant enhanced electron density on Ti as a consequence of relatively small electronegativity of N comparing with O [33], indicating that chemical binding between two components was possibly formed instead of a simply physical mixture.…”

The Complex Role of Carbon Nitride as a Sensitizer in Photoelectrochemical Cells

“…In addition, the C 1s spectrum also clearly shows the C-O bonding at 286.7 eV ( Figure S7a, Supporting Information), implying the formation of direct electronic coupling between TiO 2 and C 3 N 4 , which is responsible for the positive shifts of the Ti 2p 3/2 and the O 1s peaks because C 3 N 4 acts apparently as a strong electron withdrawing group on the TiO 2 surface. Interestingly, this kind of chemical interaction between TiO 2 and C 3 N 4 has not been reported previously although a few TiO 2 /C 3 N 4 composites were prepared, [17,18] indicating the peculiarity of the in situ vapor transport based growth mode of C 3 N 4 on mesoporous TiO 2 . In addition, the shift of Ti 2p 3/2 peak to higher binding energies implies that nitrogen doping of TiO 2 during the synthesis could be excluded.…”

“…From there, they usually transfer to the TiO 2 conduction band (CB) due to the difference in energy (path 1 and 2, Figure 4b). [18,21] The thermodynamically favorable electron injection is thereby driving charge separation. Subsequently, the negative charges transport through the TiO 2 nanoparticles and reach the conducting transparent elec- trode, while holes transfer to the electrolyte.…”

Synthesis of the Ag/AgCl/g‐C3N4 Composite with High Photocatalytic Activity under Visible Light Irradiation

“…[62] The higher the intensity of PL emission, the higher the recombination rate of photoexcited charge carriers and the lower the photocatalytic activity. [54,63] As shown in Figure 9, all products demonstrate a main emission peak at approximately 450 nm, which is attributed to the emission of bandgap transition with the energy of light equal to the bandgap energy of pure g-C 3 N 4 . [53,54] Among these products, pure g-C 3 N 4 shows the highest PL emission intensity.…”

“…Therefore, the interfaces and heterostructures between Ag/ AgCl and g-C 3 N 4 decreased because of the agglomeration and the increased size of Ag/AgCl nanoparticles, which resulted in decreased charge separation efficiency and photocatalytic activity. [33,54] A suitable amount and high dispersion of Ag/AgCl in the composites are important for the improved photocatalytic performance.…”