ABSTRACT
The effective utilization of visible light is required for exploiting photocatalytic reactions in indoor and outdoor environments. In this study, Pd-supported BiVO4 microspheres (Pd-BiVO4) were prepared for visible light-induced photocatalytic reactions. Under irradiation with a white light-emitting diode, the obtained Pd-BiVO4 composite exhibited considerably improved catalytic activity for the decomposition of an organic dye compared with other BiVO4 catalysts. The Pd-BiVO4 composite was also effective for catalytic organic transformation via the visible light-induced Suzuki-Miyaura coupling reaction. The photogenerated electrons in the conduction band of BiVO4 flowed to the Pd nanoparticles and amplified cross-coupling reaction. The influence of the crystal structure and grain size of BiVO4 and the role of the deposited Pd nanoparticles were fully investigated to elucidate the visible light activity of the catalyst. This system highlights the possibility of an indoor light source with low energy density for sustainable organic transformations.
ABSTRACT
In this study, the reaction mechanisms of metal-semiconductor composites used as photocatalysts were demonstrated by first preparing bismuth vanadate (BiVO4) and then performing photodeposition of metal nanoparticles. The photocatalytic activity of metal-BiVO4 (M-BiVO4, where M = Pt, Au, Ag) composites were evaluated through dye decomposition under UV-vis irradiation. The photocatalytic efficiency was significantly enhanced after Pt deposition as compared to other M-BiVO4 composites. The size or shape of BiVO4 was not the main factor for the efficiency of Pt-BiVO4. However, a deposited Pt co-catalyst was essential for the photocatalytic decomposition of dye on the BiVO4 surface. Radical scavengers were employed to elucidate the reaction mechanism during the photocatalytic reaction with the Pt-BiVO4 composite. This study provides details on the reaction mechanism of the photocatalytic reaction on Pt at the BiVO4 surface under solar irradiation.
ABSTRACT
A single-crystalline Bi2S3 nanowire array (Bi2S3NWA) is synthesized by an in situ hydrothermal reaction on the surface of a Bi2MoO6 film. As no additional source of Bi3+ is provided during the process, the Bi2MoO6 layer acts as the Bi3+ source for the synthesis of Bi2S3 nanowires. The fabricated Bi2MoO6/Bi2S3NWA electrode exhibited an increased photoelectrochemical (PEC) sulfite oxidation activity, which is attributed mainly to the effective interface obtained by the in situ hydrothermal growth, compared to other Bi2S3 electrodes. The generated electron from the Bi2S3 conduction band rapidly transfers to that of Bi2MoO6, yielding an enhanced electron separation of Bi2S3. Furthermore, the single-crystalline Bi2S3 nanowire can provide a fast electron pathway to Bi2MoO6 through its single domain, which also contributes to the improved PEC activity.
ABSTRACT
BiVO4 crystals synthesized by an ultrasonic-assisted method (Sono-BiVO4 ) showed improved efficiency as a heterogeneous photocatalyst under visible-light irradiation. Sono-BiVO4 was successfully used for the C-C bond cleavage of alkenes to generate carbonyl compounds. Styrene derivatives were converted into carbonyl compounds in the presence of Sono-BiVO4 under highly sustainable conditions requiring only natural sources, that is, molecular oxygen, visible light, and water at room temperature. Additionally, Sono-BiVO4 could be easily separated from the reaction mixture and reused.
