Highly Efficient and Selective Oxidation of Aromatic Alcohols Photocatalyzed by Nanoporous Hierarchical Pt/Bi₂WO₆ in Organic Solvent-Free Environment

Abstract

Selective conversion of aromatic alcohols into corresponding aldehydes is important from energy and environmental stance. Here, we describe highly selective (>99%) and efficient conversion (>99%) of aromatic alcohols (e.g., 4-methoxybenzyl alcohol and 4-nitrobenzyl alcohol) into their corresponding aldehydes in the presence of Pt-modified nanoporous hierarchical Bi2WO6 spheres in water under simulated sunlight at ambient conditions. Overoxidation of p-anisaldehyde, formed during photooxidation process, was not observed until comprehensive alcohol oxidation was attained. Furthermore, the catalyst showed substantial oxidation under dark and course of conversion was different than that of under light. Dependency of alcohol oxidation on substrate concentration, photocatalyst amount, and Pt loading was studied. The effect of various radical scavengers was investigated, and the rate-determining step was elucidated. It has been envisaged that the reduction site of semiconductor photocatalysts plays more decisive role in determining the selectivity as alcohol preferably get oxidized over that of water. Furthermore, the chemical stability and recyclability of the photocatalyst were investigated.

Bismuth Tungstate‐Reduced Graphene Oxide Self‐Assembled Nanocomposites for the Selective Photocatalytic Oxidation of Alcohols in Water

“…The triethanolamine (TEA) serves as a scavenger of holes, and the oxidation of BA was remarkably prohibited, which implies that the photocatalytic conversion of BA is driven primarily by photoinduced holes (h + ). Moreover, the addition of an electron scavenger (NH 4 ) 2 S 2 O 8 led to a slight increase in the conversion of BA, which further confirms that photogenerated holes were crucial for the selective oxidation. The addition of benzoquinone (BQ; a scavenger for O 2 .− ) resulted in a moderate decrease in the conversion of BA, which suggests that O 2 .− might be involved in the oxidation of BA.…”

Mild ultrasound-assisted synthesis of TiO 2 supported on magnetic nanocomposites for selective photo-oxidation of benzyl alcohol

“…Metal oxide based catalysts such as TiO2, [11][12][13] Nb2O5, 14 and ZnO 15 have been well explored for the alcohol oxidation in presence of UV irradiation. Incorporation of various noble metals including Au, 16 Pd, 17 and Pt 18,19 on different photoactive catalyst supports has been reported to achieve improved activities even under visible light conditions. However, the use of noble metals is not suitable for the large scale transformation and in terms of practical implication.…”

Facile synthesis of porous Bi2WO6 nanosheets with high photocatalytic performance

“…In addition, Bi 2 WO 6 has been demonstrated to be an effective visible-light photocatalytic material for the decomposition of various organic substances and water splitting owing to its narrow band gap (ca. 2.6-2.7 eV) [23][24][25] . Considering the strong dependence of the photocatalytic performance on its shape, various nanostructured Bi 2 WO 6 photocatalysts have been widely reported to improve its photocatalytic activity in addition to the well-known nanoparticles with a high specific surface area.…”