A graphene-coupled Bi₂WO₆ nanocomposite with enhanced photocatalytic performance: a first-principles study

Abstract

An experimentally synthesized graphene/Bi2WO6 composite showed an enhancement of the visible-light photocatalytic activity, while the underlying mechanism is not known. Here, first-principles calculations based on density functional theory were performed to explore the various properties of the graphene/Bi2WO6(010) composite aiming at gaining insights into the mechanism of its photocatalytic activity. The stability, electronic properties, charge transfer, and visible-light response were investigated in detail on the Bi2WO6(010) surface coupled with graphene. An analysis of charge distribution and Bader charge shows that there is a strong covalent bonding between graphene and the Bi2WO6(010) surface. The covalent interaction induces a small bandgap in graphene. The interband transition of graphene and the surface states of the Bi2WO6(010) surface would cause the absorption spectrum of graphene/Bi2WO6(010) to cover the entire visible-light region and even the infrared-light region. The photogenerated electrons flow to graphene from the conduction band of Bi2WO6 under the built-in electric field and band edge potential well. Thus, graphene serves as a photogenerated electron collector and transporter which significantly reduces the probability of electron-hole recombination and increases catalytic reaction sites not only on the surface of graphene but on also the surface of Bi2WO6. The decrease of charge recombination is possibly responsible for the enhancement of the visible-light photocatalytic activity of the graphene/Bi2WO6(010) nanocomposite.

Tunable Type-II BiVO4/g - C

“…4 ), and E(BiVO 4 ) are the total energies of the relaxed BiVO 4 /g-C 3 N 4 heterostructure, g-C 3 N 4 (001), and BiVO 4 (010) slabs, respectively; S is the area of the interface. The calculated adhesion energies for BiVO 4 /SL-g-C 3 N 4 , BiVO 4 /BL-g-C 3 N 4 , and BiVO 4 /TL-g-C 3 N 4 heterostructures are -0.20 eV/Å 2 , -0.25 eV/Å 2 , and -0.18 eV/Å 2 , respectively, suggesting that these structures are stable.These adhesion energies are consistent with those for g-C 3 N 4 (001) on the Zn 2 GeO 4 (110) surface (-0.18 eV/Å 2 )[61] and graphene-coupled Bi 2 WO 6 (010) surface (-0.18 eV/Å 2 )[8]. It should be noted that the calculated adhesion energy is significantly greater than that for typical vdW systems such as graphite, suggesting that both physical and chemical effects contribute to the surface adhesion.…”

“…One of the most widely explored strategies is the use of photocatalytic heterojunctions [2,[5][6][7]. Previous work [8,9] has demonstrated that the construction of two semiconductors with suitable electronic structures may exhibit superior photoactivity than single photocatalysts. In particular, a type II band alignment at the heterostructure interface can facilitate rapid separation of photogenerated electron−hole pairs, resulting in significantly improved photocatalytic performance.…”

Crystal Engineering of Bi2WO6 to Polar Aurivillius-Phase Oxyhalides

“…The stability of Bi-O termination was also suggested in a previous computational study. 60 Furthermore, monolayer Bi 2 WO 6 was recently synthesized and suggested to exhibit Bi-O termination. 23…”

Recent Progress in the Development of Semiconductor‐Based Photocatalyst Materials for Applications in Photocatalytic Water Splitting and Degradation of Pollutants

“…The enhanced charge transfer and visible light absorption of graphene/anatase TiO 2 (G/ATN) and graphene/Bi 2 WO 6 (010) nanocomposites was attributed to the difference in their work functions within first‐principles DFT calculation. The Bader charge and charge distribution analysis revealed a strong covalent bonding between graphene and monolayer Bi 2 WO 6 (010) surface, which induces a narrow band gap.…”