Temperature‐Dependent Photoredox Catalysis for CO₂ Reduction Coupled with Selective Benzyl Alcohol Oxidation over ZnIn₂S₄/In₂O₃ Heterostructure

Abstract

CO2 reduction (CO2RR) with selective benzyl alcohol (BA) oxidation in a single photoredox reaction can simultaneously utilize photogenerated electrons and holes to realize efficient production of fuels and value‐added chemicals. Herein, a unique 2D/1D ZnIn2S4/In2O3 (ZIS/In2O3) heterostructure is developed displaying outstanding performance for photoredox catalysis. As is unequivocally illustrated by various advanced ex situ/in situ characterizations and theoretic calculations, the notable catalytic performances originate from the built‐in interfacial electric field within the ZIS/In2O3 heterostructure, which strongly ameliorates the separation and transport of charge carriers. Remarkably, the catalytic activity can further be boosted after coupling the additional thermal treatments, and the product selectivity is highly temperature dependent. Thereby, the precise formation of targeted products, which can serve as valuable industrial products and fuels can be controlled by changing the reaction temperatures, including obtaining the syngas with different H2/CO ratios from CO2 reduction, as well as benzaldehyde, hydrogenated benzoin, and dibenzyl ether (never reported for BA during photocatalysis) from the BA conversion. This study offers a constructive and inspiring contribution to reasonably developing photoredox catalysts, which can fully utilize photogenerated electrons and holes, as well as demonstrate how to controllably yield the targeted products by coupling thermo‐ and photoredox catalysis.

Tailoring Charge Separation in ZnIn2S4@CdS Hollow Nanocages for Simultaneous Alcohol Oxidation and CO2 Reduction under Visible Light

“…This is because the electron-donating group is easy to react with the photoexcited holes . More importantly, such high activity of the ZnIn 2 S 4 @CdS heterostructure is far beyond the majority of photocatalysts for simultaneously photocatalytic reduction of CO 2 and oxidation ArCH 2 OH in one reaction system (Figure a, details are listed in Table S1), such as ZIS 4 –CTAB, Ni 12 P 5 /ZnIn 2 S 4 , ZnIn 2 S 4 /In 2 O 3 , etc. − While for FAPbBr 3 /Bi 2 WO 4 with a higher CO production rate, the UV–vis light was used. Here, visible light was used for ZnIn 2 S 4 @CdS.…”

“…The “blank” means the reaction system under visible light irradiation but without catalysts. The triplet peaks are the intrinsic peaks of the active TEMPO, which can be reduced by trapping electrons or holes. , Specifically, the weaker the signal appeared, the greater the separation efficiency became. Compared with the blank, the EPR signals are both decreased for checking electrons and holes over CdS, ZnIn 2 S 4 , and ZnIn 2 S 4 @CdS.…”

“…Xu et al reported that reduction of CO 2 into syngas coupled with oxidative C–N bond formation could be achieved on BP/ZIS heterostructure . However, the CO 2 reduction coupled with aromatic alcohol oxidation is dissatisfactory, because the photocatalytic activity is very low, and/or the reductive H 2 evolution is the main reaction. − Therefore, fabricating photocatalysts for efficient driving of CO 2 reduction coupled with aromatic alcohol oxidation is still a challenge.…”

“…It should be also noted that fast recombination of photoexcited charge carriers is presence in the individual metal sulfides. − This requires that the metal sulfides be modified to endow them with expected charge separation. Although cocatalysts (such as Cu), molecule modifications (for example CTAB), and metal oxide complexes (such as CdS/TiO 2 and ZnIn 2 S 4 /In 2 O 3 ) can improve charge separation, the H 2 production is far more than CO production. Vacancies can improve the mole ratio of CO/H 2 , while the photocatalytic activity and stability need to be further enhanced.…”

“…However, the sluggish oxidation reaction (2H 2 O + 4h + → 4H + + O 2 ) triggered by photoexcited holes (h + ) greatly limited the photocatalytic activity of these photocatalysts. − Although sacrificial reagents can help to improve CO 2 reduction activity, the expenses should not be overlooked such as cost-push, whole energy dissipation, secondary pollution, etc . Recently, the new paradigm of coupling CO 2 reduction with oxidative organic synthesis has been reported to simultaneously utilize photogenerated electrons and holes. − This new artificial photosynthesis with dual functions can simultaneously realize the oxidation of organics into value-added fine chemicals via dehydrogenation by consuming holes and the reduction of CO 2 into fuels via hydrogenation by expanding electrons. Thus, an atom economic and carbon neutral cycle is established.…”