A Highly Efficient Composite Catalyst Constructed From NH2-MIL-125(Ti) and Reduced Graphene Oxide for CO2 Photoreduction.

Yunxia Zhao,Yuanyuan Miao,Wei Cai,Jiaxin Chen,Yunfei Bu

doi:10.3389/fchem.2019.00789

Abstract

Substantial consumption of fossil fuels causes an increase in CO2 emissions and intensifies global pollution problems, such as the greenhouse effect. Recently, a new type of ultra-low-density porous material, metal-organic frameworks (MOFs), has been developed for the photocatalytic conversion of CO2. Herein, a composite photocatalytic catalyst based on NH2-MIL-125(Ti) and reduced graphene oxide (rGO@NH2-MIL-125) was fabricated through a facile “one-pot” process. The acquired materials were characterized to obtain their structures, morphologies, and optical information. The experimental results showed that methyl formate (MF) was the predominant reaction product, and rGO@NH2-MIL-125 exhibited the highest yield of 1,116 μmol·g−1·h−1, more than twice that of pure MIL-125. The high photoactivity of rGO@NH2-MIL-125 can be ascribed to the effective spatial separation and transfer of photoinduced carriers, largely due to the synergistic effect of amino functionality and rGO incorporation. rGO@NH2-MIL-125 also displayed acceptable repeatability in cyclic runs for CO2 reduction.

Highlights

With the economic and social development, the CO2 concentration in the atmosphere is increasing, causing global warming, and other climate problems
The experimental results showed that methyl formate (MF) was the predominant reaction product, and reduced graphene oxide (rGO)@NH2-MIL-125 exhibited the highest yield of 1,116 μmol·g−1·h−1, more than twice that of pure MIL-125
The X-ray diffraction (XRD) pattern of as-prepared NH2-MIL-125 is in good agreement with other reports (Kim et al, 2013; Guo et al, 2015; Li et al, 2018b)

Summary

INTRODUCTION

With the economic and social development, the CO2 concentration in the atmosphere is increasing, causing global warming, and other climate problems. MOF photocatalysts with highly efficient optical and electronic properties resulted in good photocatalytic oxidation performance and stability for nitric oxide and acetaldehyde (Li et al, 2018b). A NH2-MIL-125(Ti) and reduced graphene oxide (rGO) composite was synthesized in situ by a facile “one-pot” method as an efficient photocatalyst for CO2 reduction. Titanium isopropoxide (1.5 mmol) and H2BDC (6 mmol) were dissolved in a mixed solvent of DMF and CH3OH (18 mL/2 mL) under magnetic stirring for 0.5 h. The following procedures were the same as those for the above two pristine MOFs. The obtained gray powder was labeled as rGO@NH2-MIL-125. The reactant-product mixed solution was analyzed by gas chromatography (GC 9790II, Fuli, China), and the photocatalytic efficiency was assessed by the yield of the product methyl formate (MF)

RESULTS AND DISCUSSION

CONCLUSIONS

DATA AVAILABILITY STATEMENT