Selective Photocatalytic Oxidation Of Benzyl Alcohol Research Articles

Poly(dibenzothiophene-S,S-dioxide)-Fe2O3 heterojunction for photocatalytic hydrogen production coupled with selective oxidation of benzyl alcohol

Photocatalytic conversion of benzyl alcohol (BA) into value-added fine chemicals and hydrogen (H2) in water medium provides a novel strategy for green synthesis. The construction of Z-scheme heterostructures not only realize enhanced charge-separation efficiency, but also remain strong drive force for photocatalytic reaction, which exhibit great potentials toward simultaneously generating benzaldehyde (BAD) and H2. Herein, we report a noble-metal-free Z-scheme photocatalytic system consisting poly(dibenzothiophene-S,S-dioxide) (PSO) and α-Fe2O3 for selective oxidation of BA with synchronous H2 production. Such nanocomposites can effectively transfer and reduce the recombination of photoexcited charge carriers, therefore maintaining the oxidizability of holes of α-Fe2O3 and the reducibility of electrons of PSO. As expected, PSO-Fe2O3 with a mass of ∼5 mg under optimal composition ratio exhibited an impressive photocatalytic activity with BAD and H2 yields up to 23.1 and 29.5 μmol h−1, respectively, which is among the top photocatalytic performance reported so far for selective photocatalytic oxidation of BA in the aqueous solution.

N-CQDs act as electronic warehouse in N-CQDs/CdS regulate adsorption energy to promote photocatalytic selective oxidation of aromatic alcohols

The benzaldehyde (BAD) produced by the benzyl alcohol (BA) oxidation method is comprehensively applied to food and pharmaceutical fields. However, the selectivity and conversion of photocatalytic selective oxidation of BA in aqueous solution are still far from expectation. Herein, N-CQDs/CdS composites were synthesized by the in-situ precipitation method. N-CQDs served as an "Electronic Warehouse" to boost the separation efficiency of the carrier. The electron transferred from CdS to N-CQDs made electron on the N-CQDs surface enrich, which was conducive to the formation of superoxide radicals (·O2-).·O2- and h+ could efficiently oxidize BA to BAD. In addition, according to density functional theory (DFT), the adsorption energies of BA and BAD on N-CQDs/CdS were distinctly greater than that of CdS. BAD tended to desorb from the 7.5 N-CQDs/CdS surface, and BA preferred to adsorb on the CdS surface. However, BAD was difficult to desorb from the CdS surface, resulting in the poisoning of CdS. 7.5 N-CQDs/CdS exhibited the BA conversion of 60.4% and BAD selectivity of 99%, which was 2.2 times higher than that of original CdS. This work was expected to provide a theoretical basis for improving photocatalyst carrier separation efficiency and alcohol selective oxidation performance.

Chalcogenide photocatalysts for selective oxidation of aromatic alcohols to aldehydes using O2 and visible light: A case study of CdIn2S4, CdS and In2S3

CdIn2S4, CdS and In2S3 photocatalysts were fabricated via a facile solvothermal method using indium chloride, cadmium nitrate and thiacetamide as precursors. The physicochemical and optical properties of the as-prepared samples were characterized by a series of techniques. The photocatalytic activities of the as-prepared samples were evaluated by selective aerobic oxidation of aromatic alcohols to corresponding aldehydes under visible light illumination. Compared with pure In2S3 and CdS samples, CdIn2S4 photocatalyst shows superior photocatalytic performance for selective oxidation of benzyl alcohol (BA) to benzaldehyde (BAD). Under the optimal conditions, the conversion and selectivity for photocatalytic selective oxidation of BA to BAD are 80.1 and 98.8% under visible light irradiation for 2 h, respectively. The excellent photocatalytic performance of CdIn2S4 photocatalyst should be ascribed to its unique structure with a favorable absorptivity, appropriate conduction band and valence band positions and longer lifetime of photogenerated charge carriers. A possible reaction mechanism for selective oxidation of BA to BAD over CdIn2S4 photocatalyst with O2 and visible light is proposed. It is hoped that the current work could offer an avenue to prepare high-performance chalcogenide photocatalysts used in the field of photocatalytic selective organic transformations.