New Understanding on Photocatalytic Mechanism of Nitrogen-Doped Graphene Quantum Dots-Decorated BiVO₄ Nanojunction Photocatalysts

Abstract

Bismuth vanadate (BiVO 4 ) is a promising candidate as a visible-light-driven photocatalyst in the aspect of practical applications. To investigate the origin of active species from BiVO 4 and understand the influence of the variations of the photocatalytic process, comparative studies on zero-dimensional nitrogen-doped graphene quantum dot (NGQD)-decorated BiVO 4 have been carried out for methylene blue photodegradation. It was found that the hydroxyl group-rich NGQD surface and the established heterojunction structure between NGQDs and BiVO 4 were greatly beneficial for the conversion of the • OH radical. With NGQD decoration, the dominant oxidant species for NGQDs/BiVO 4 were confirmed to be • OH and H 2 O 2 , rather than holes originating from the valence band of unmodified BiVO 4 . The synergistic photocatalytic mechanism with respect to the interfacial charge transport and the conversion of active species was proposed. The achievement of the controllable active species significantly altering the activity may be applied for different photocatalytic reactions.

Facet-Dependent Interfacial Charge Transfer in TiO2/Nitrogen-Doped Graphene Quantum Dots Heterojunctions for Visible-Light Driven Photocatalysis

“…light absorption edge was slightly blue shifted [21]. The UV-vis spectrum of NGQDs is shown in Figure S4d, and the band gap was approximately 1.56 eV, according to our previous work [30,41]. After decorating NGQDs, it was found that there was an increasing visible light absorption for all composites.…”

A composite of platelet-like orientated BiVO4 fused with MIL-125(Ti): Synthesis and characterization

“…Many attempts have been made to combat this through co-catalyst modifications to form heterojunctions or phase-junctions, doping with non-metals or metals such as Fe, W, N, P and Mo, and tuning morphology with the aim to expose most reactive facets 10 . Doping involves the introduction of impurity levels that act as electron or hole traps thus facilitation separation of electrons and holes 12,13 . Co-catalyst modifications to form heterojunctions or phase-junctions depends on the band-edge staggered alignment that facilitate the shuttle of electrons and holes to different materials by separating the respective charge transporters.…”

Interplay between Mesocrystals of CaTiO3 and Edge Sulfur Atom Enriched MoS2 on Reduced Graphene Oxide Nanosheets: Enhanced Photocatalytic Performance under Sunlight Irradiation

“…To further validate the role and generation of active species in the photocatalytic degradation of organic pollutants, it is important to understand the relative positions of the VB and CB potentials in the CTMG20 nanocomposite with respect to the reduction potentials of O 2 / * O 2 − (−0.33 eV), O 2 /H 2 O 2 (+0.69 eV), * OH/OH − (+1.99 eV) and * OH/H 2 O (+2.68 eV) . In this regard, the relative band edge positions of the photocatalyst were calculated by using the following equations [Eqs.…”