Visible light-induced selective oxidation of cyclohexane to cyclohexanone on Cr–Si binary oxide with molecular oxygen

Abstract

Cr-Si binary oxide prepared by a sol-gel method, when activated by visible light, catalyses highly selective oxidation of cyclohexane to cyclohexanone with molecular oxygen.

Highly efficient and selective sunlight-induced photocatalytic oxidation of cyclohexane on an eco-catalyst under a CO2 atmosphere

“…However, there have been few efficient photocatalytic processes under sunlight or visible light irradiation. [24][25][26][27] In this communication, we report a high level of efficient and selective sunlight-induced cyclohexane oxidation on TiO 2 (P25) modified with iron oxide 28,29 by conducting the reaction under CO 2 . This photocatalyst is economically favorable, as well as environmentally benign, since iron is harmless and abundant in nature.…”

Condensed ferric dimers for green photocatalytic synthesis of nylon precursors

“…Given that typical iron oxides don't have electronic band structures (conduction band potentials) capable of reducing O 2 ,9 these results demonstrate that the ferric dimers in AFO/SBA have an electronic structure that is completely different from that of typical iron oxides and show a charge separation efficiency that is remarkably higher than even that of P25, which is a benchmark photocatalyst for the oxidation of organic compounds 33. Based on the structural similarity between the ferric dimers and molecular sized photocatalysts, we can explore the mechanism for photocatalytic cyclohexane oxidation on AFO/SBA according to a proposed mechanism based on molecular sized photocatalysts 34. First, excitation of the photocatalyst produces excited Fe 2+ via an electron transfer from the coordinated O 2– (in H 2 O) to the center Fe 3+ , and the resulting electrophilic O – reacts with cyclohexane to produce a key intermediate, the cyclohexyl radical (Fig.…”

Applications of Single-site Photocatalysts to the Design of Unique Surface Functional Materials

“…1). These charge transfer excited states, i.e., the electron-hole pair state which is located quite near to each other as compared to the electron and hole produced in semiconducting materials such as TiO 2 , play a significant role in various photocatalytic reactions such as the decomposition of NO [9][10][11][12], the photo-reduction of CO 2 with H 2 O [13][14][15][16], the degradation of organic impurities in water [17][18][19][20], the photo-oxidation of hydrocarbons [21][22][23][24][25][26][27][28][29][30] and the photo-induced metathesis of alkanes [31,32]. These single-site photocatalysts display quite different reaction mechanisms from those observed on semiconducting metal oxide photocatalysts such as TiO 2 in which the photo-electrochemical reaction mechanism plays an important role.…”

“…These isolated metal oxide moieties in the silica matrixes have been named as ''single-site photocatalyst'' [5][6][7][8]. As ''single-site photocatalyst'', isolated Ti [9][10][11][12][13][14][15][16][17][18][19][20], V [21][22][23], Cr [24][25][26][27][28][29][30], Mo [31,32], and W oxide moieties can be incorporated in the frameworks of silica-based porous materials and can perform the unique photocatalytic reactions. Under UV-light irradiation, these single-site photocatalysts form charge transfer excited state which can show the highly active and selective photocatalytic performance (Fig.…”