Visible Light Mediated Photocatalytic Reduction of CO2 to Non-fossil Fuel and Valuable Products by Polyaniline-TiO2 Nanocomposites

Abstract

CO<inf>2</inf>, a major contributor for global warming may be considered as a free source of carbon and can be converted into hydrocarbons. Mimicking the photosynthesis process that utilizes light energy to convert CO<inf>2</inf>, is the favorable option, and solar energy may be harnessed. The present paper reports the visible light mediated photocatalytic reduction of CO<inf>2</inf> to formic acid, formaldehyde and methanol using Polyaniline-TiO<inf>2</inf> nanocomposites (PANI-TiO<inf>2</inf>) in aqueous media under ambient conditions. The optimum TiO<inf>2</inf> content in the nanocomposite to maximize the yield of formaldehyde and formic acid is 18.2% by weight, and it has a band gap of 2.81 eV. The yield of formaldehyde, formic acid and methanol obtained were 80.57, 32.17 and 6.3 μmole/g catalyst, respectively, in eight hours with 0.3 g/L catalyst loading. The catalyst loading of 0.7 g/L is the optimum loading to maximize the yield of formaldehyde and formic acid. Maximum yield of methanol was obtained with PANI-TiO<inf>2</inf> containing 35% TiO<inf>2</inf>. This approach can lead the energy sector toward a non-fossil fuel-based economy. © 2022, King Fahd University of Petroleum & Minerals.