Photocatalytic reduction of carbon dioxide to methanol and formic acid by graphene-TiO2

• Published in: Journal of the Air & Waste Management Association (1995) Vol. 64; no. 5; pp. 578 - 585
• Main Authors: Zhang, Qian, Lin, Cheng-Fang, Jing, You Hai, Chang, Chang-Tang
• Format: Journal Article
• Language: English
• Published: United States Taylor & Francis 04-05-2014
• Subjects: Carbon Dioxide - chemistry; Catalysis; Formates - chemistry; Graphite - chemistry; Hydrogen-Ion Concentration; Methanol - chemistry; Molecular Structure; Photochemical Processes; Titanium - chemistry
• ISSN: 1096-2247; 2162-2906
• DOI: 10.1080/10962247.2013.875958

Graphene-TiO
2
was obtained by reduction of graphite oxide by the hydrothermal method. Using photocatalytic activity to reduce carbon dioxide to methanol and formic acid was investigated in this study. The results show that the graphene loading affects the absorption of light in the visible light region. A larger surface area can also improve the catalytic activity. The largest yield of methanol and formic acid, under light of 365 nm, can reach 160 and 150 μmol g
−1
, respectively, with 8.5% graphene loading. An increase in graphene loading can enhance photocatalytic performance, but too much will also decrease the reduction efficiency by shielding the light from reaching the catalytic surface. The effect of pH was also investigated. The mechanism of the reaction was also discussed in this study.
Implications: 
Graphene-TiO
2
hybrids were prepared by the hydrothermal method. Surface area and visible light adsorption increased with the graphene loading. Increased graphene loading improved the methanol and formic acid production. Too much graphene loading will decrease the reduction efficiency. The effect of pH shows that the HCO
3
−
species prefers the formation of formic acid. The mechanism of the reaction was also discussed in this study.