Solid Base Bi₂₄O₃₁Br₁₀(OH)_δ with Active Lattice Oxygen for the Efficient Photo‐Oxidation of Primary Alcohols to Aldehydes

Abstract

The selective oxidation of primary alcohols to aldehydes by O2 instead of stoichiometric oxidants (for example, MnVII, CrVI, and OsIV) is an important but challenging process. Most heterogeneous catalytic systems (thermal and photocatalysis) require noble metals or harsh reaction conditions. Here we show that the Bi24O31Br10(OH)δ photocatalyst is very efficient in the selective oxidation of a series of aliphatic (carbon chain from C1 to C10) and aromatic alcohols to their corresponding aldehydes/ketones under visible‐light irradiation in air at room temperature, which would be challenging for conventional thermal and light‐driven processes. High quantum efficiencies (71 % and 55 % under 410 and 450 nm irradiation) are reached in a representative reaction, the oxidation of isopropanol. We propose that the outstanding performance of the Bi24O31Br10(OH)δ photocatalyst is associated with basic surface sites and active lattice oxygen that boost the dehydrogenation step in the photo‐oxidation of alcohols.

Recent Progress on Two-Dimensional Materials

“…The donated protons further accept the conduction band electrons to generate metastable Hads under irradiation, which can then be rapidly scavenged by hydrogen acceptors (A) to form valuable organic compounds, rather than H2 gas. Moreover, joint utilization of basic surface sites and active lattice oxygen in Bi24O31Br10(OH)δ is a promising way to selectively oxidize aliphatic and aromatic alcohols to the corresponding aldehydes/ketones due to boosted dehydrogenation in photooxidation of alcohols 1194 . Defect engineering in LDHs also play a vital role in the hydroxylation of benzene 1195 , selective oxidation of aromatic alcohols 1196 , and hydroxylation of phenol 1197 .…”

Review: applications of the functional photocatalysts BiOX (X = Cl, Br, I) for clean energy, the environment, and future photobiorefineries

“…For example, benzyl alcohol was photocatalytically oxidized to benzaldehyde using Bi 12 O 17 Cl 2 , 123 whereby charge separation and superoxide production by photogenerated electrons synergistically enhanced the selectivity to 99% and yield to 44%. In another typical study, modified Bi 24 O 31 Br 10 (OH) x was used to aid converting primary alcohols to the corresponding aldehydes, 125 showing a quantum efficiency of isopropanol of 71% at 450 nm irradiation in 24 h. These studies replaced expensive noble metal-based oxidation reactions systems with clean photooxidations; some findings are listed in Table 1.…”

Reactive oxygen species on transition metal-based catalysts for sustainable environmental applications

“…Sabaté can selectively oxidize primary alcohols to aldehydes under visible light irradiation at room temperature using air. 301 The XPS analysis of the O1s spectra reveals that O L is converted to the adsorbed water on the catalyst surface aer the reaction. With the developed catalyst, (1) aromatic alcohols are oxidized considerably faster than aliphatic alcohols, (2) benzyl alcohols with different functional groups (e.g., p-NO 2 , p-F, p-Cl, p-CH 3 , p-OCH 3 ) are fully air-oxidized to the corresponding aldehydes with $99% selectivity within 4 h of illumination, and (3) there is no over-oxidation to carboxylic acids, CO, or CO 2 in all cases.…”

“…Dai et al found that the O L -mediated selective photo-oxidation of alcohols over Bi 24 O 31 Br 10 (OH) d starts with the photo-dehydrogenation of alcohols to form adsorbed hydrogen species on the surface of the photocatalyst. 301 The O L of Bi 24 O 31 Br 10 (OH) d then oxidizes the alcohol to form aldehydes and OVs, and the OVs are subsequently healed by mild oxidants (O 2 or benzoquinone) to complete the photocatalytic cycle.…”

“…Dai et al reported that the Bi 24 O 31 Br 10 (OH) δ photocatalyst with active O L can selectively oxidize primary alcohols to aldehydes under visible light irradiation at room temperature using air. 301 The XPS analysis of the O1s spectra reveals that O L is converted to the adsorbed water on the catalyst surface after the reaction. With the developed catalyst, (1) aromatic alcohols are oxidized considerably faster than aliphatic alcohols, (2) benzyl alcohols with different functional groups ( e.g.…”