CuMoxW(1-x)O4 Solid Solution Display Visible Light Photoreduction of CO2 to CH3OH Coupling with Oxidation of Amine to Imine.

Chao Luo,Qianfei Huang,Yuxin Zhu,Guoming Xia,Xian Liu,Tian Yang,Huan Ling,Hongming Wang,Wennan Zou

doi:10.3390/nano10071303

Abstract

The photoreduction of carbon dioxide (CO2) to valuable fuels is a promising strategy for the prevention of rising atmospheric levels of CO2 and the depletion of fossil fuel reserves. However, most reported photocatalysts are only active in the ultraviolet region, which necessitates co-catalysts and sacrificial agents in the reaction systems, leading to an unsatisfied economy of the process in energy and atoms. In this research, a CuMoxW(1-x)O4 solid solution was synthesized, characterized, and tested for the photocatalytic reduction of CO2 in the presence of amines. The results revealed that the yield of CH3OH from CO2 was 1017.7 μmol/g under 24 h visible light irradiation using CuW0.7Mo0.3O4 (x = 0.7) as the catalyst. This was associated with the maximum conversion (82.1%) of benzylamine to N-benzylidene benzylamine with high selectivity (>99%). These results give new insight into the photocatalytic reduction of CO2 for valuable chemical products in an economic way.

Highlights

For energy conservation and environmental protection, direct conversion of CO2 into a source of carbon fuels is an ideal solution [1,2,3,4,5,6,7]
Very recently, Ling and colleagues [50] demonstrated that CuxAgyInzZnkS solid solutions customized with RuO2 or a Rh1.32Cr0.66O3 co-catalyst showed high photocatalytic activity for the reduction of CO2 into CH3OH with a yield up to 118.5 μmol g–1 h–1 under visible light irradiation
A series of CuWxMo(1-x)O4 solid solutions were prepared and applied to the reduction of CO2 into CH3OH coupling with the conversion of aromatic amine into its corresponding imine

Summary

Introduction

For energy conservation and environmental protection, direct conversion of CO2 into a source of carbon fuels is an ideal solution [1,2,3,4,5,6,7]. It has been confirmed that forming a solid solution between semiconductors is an excellent method in the development of visible light-driven photocatalysts for sensitive photoreduction of CO2 [37,38,39,40] and is widely applied in photocatalytic water splitting and pollutant degradation, while exhibiting better performance than single components comprising the solid solution [41,42,43,44,45,46] Taking this into account, a series of solid solution photocatalysts, such as BiOBrxCl1-x [47], ZnxCd1-xS [48], GaN:ZnO [49], and zinc gallogermanate [39], have been synthesized and examined for CO2 reduction under visible light irradiations. A CuMoxW(1-x)O4 solid solution was synthesized by a facile hydrothermal method and examined for the photocatalytic reduction of CO2 under visible light irradiation without the addition of any co-catalysts and sacrificed reagents in the system In this process, CO2 was reduced to CH3OH by photo-induced electrons, while amine was selected as the “hydrogen-donor” to capture the photogenerated holes. The amine was converted into imine, resulting in good energy and atomic economies

General

The Preparation of Solid Solution Photocatalysts

XRD and EDX Analysis

SEM and TEM Analysis

Findings

Conclusions