g-C₃N₄/Pt/BiVO₄ nanocomposites for highly efficient visible-light photocatalytic removal of contaminants and hydrogen generation

Abstract

Inspired by natural photosynthesis, artificial heterojunction photocatalysts have been extensively studied. Herein, a novel ternary graphitic carbon nitride/platinum/bismuth vanadate (g-C3N4/Pt/BiVO4) photocatalytic system was successfully synthesized, where Pt/BiVO4 nanosheet is anchored on the surface of layered g-C3N4, as evidenced by structural observations. Ultraviolet photoelectron spectroscopy and ultraviolet–visible diffuse reflectance spectroscopy are carried out to identify the position of the conduction band and valence band. A Z-scheme is used to interpret the superior photocatalytic performance of g-C3N4/Pt/BiVO4 and further verified by the capture of free radicals and terephthalic acid photoluminescence experiments. Compared with the g-C3N4/BiVO4 binary system, the Z-scheme g-C3N4/Pt/BiVO4 photocatalyst not only possesses enhanced carrier separation efficiency but also maintains sufficient redox properties, thus inducing superior photocatalytic activity. More importantly, the novel Z-scheme photocatalyst exhibits excellent recycle stability, which could provide inspiration for the rational design of efficient and practical photocatalysts for environmental pollution treatment. The ternary photocatalyst also exhibits significantly enhanced visible-light photocatalytic hydrogen production performance.

Constructing Heterogeneous Photocatalysts Based on Carbon Nitride Nanosheets and Graphene Quantum Dots for Highly Efficient Photocatalytic Hydrogen Generation

“…To address these challenges, a composite of semiconductor photocatalytic materials and graphene systems can be used to broaden the absorption range of visible light and enhance the light absorption intensity of its materials [ 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 ]. Due to graphene’s metallic properties, the heterojunctions constructed are transformed into Schottky heterojunctions.…”

Unravelling the Mechanisms that Drive the Performance of Photocatalytic Hydrogen Production

“…The activity of g-C 3 N 4 /Nb 2 O 5 production was also attributed to the direct Z-scheme due to the significant increase in hydrogen production compared to individual components under simulated solar light illumination, reduced recombination rate, and staggered band positions, as reported by Idrees et al [59]. Si et al also reported enhanced hydrogen production using g-C 3 N 4 /BiVO 4 [27]. Hydroxyl radicals were detected using terephthalic acid as the scavenger.…”

“…Along with the band gap, CB can also be determined. Some examples of photocatalysts that have been analyzed in this way are g-C 3 N 4 /BiVO 4 [27] or TiO 2 [87]. Computational calculations, as first-principles density functional theory (DFT), can provide insight into the coupling interactions and electron transfer at the interface of the heterostructure.…”

“…Synthesis of semiconductor-semiconductor heterojunctions (i.e., TiO 2 /g-C 3 N 4 [21], TiO 2 /CdS [22], ZnO/g-C 3 N 4 [23] , TiO 2 -WO 3 [24][25][26] or g-C 3 N 4 /BiVO 4 [27]) is another recent approach, which is a facile method with very promising results. The most remarkable features is that they contribute to avoiding charge recombination and coupling the properties of both semiconductors.…”

Construction of a Switchable g-C3N4/BiVO4 Heterojunction from the Z-Scheme to the Type II by Incorporation of Pyromellitic Diimide

“…32 For V 2p (Figure 4c), binding energies at around 516.6 and 517.8 eV are assigned to V 4+ and V 5+ in VO 4 3− (Figure 4c); the V 4+ can play the role of an electron sink to restrain the charges' recombination, which will be beneficial to improving the photocatalytic performance. 33 The O 1s spectrum is presented in Figure 4d; for BiVO 4 , the peaks centered at 529.8 and 531.1 eV are ascribed to the lattice oxygen (O 2− in the Bi−O band) and the oxygen in the surface hydroxyl species of the sample. 34,35 The other two peaks at 530.8 and 532.3 eV in the g-C 3 N 4 /PI sample are assigned to CO and the O in H 2 O, 35,36 respectively.…”