Experimental studies on photocatalytic reduction of CO2 using AgBr decorated g-C3N4 composite in TEA mediated system

Abstract

Graphitic carbon nitride modified with silver bromide (AgBr/g-C3N4) composite was prepared by modified deposition-precipitation method. The phase structure, optical property, thermo stability, morphological structure, elemental composition, surface area and surface charge of AgBr/g-C3N4 composite were characterized using various analytical techniques. XRD spectrum for AgBr/g-C3N4 composite reveals that cubic phase of AgBr crystal is deposited on the surface of g-C3N4. The AgBr/g-C3N4 composite showed slightly enhanced visible light active, which was confirmed from UV- vis absorbance spectra. The BET surface area of pure AgBr, g-C3N4 and AgBr/g-C3N4 composite were 4.802m2/g, 12.74m2/g and 15.52m2/g respectively. Subsequently, the photocatalytic activity of AgBr/g-C3N4 composite was evaluated towards the reduction of carbon dioxide (CO2) under UV light irradiation. The effects of reductants, pH, catalyst dosage and stability were also studied. The maximum production yield of methane (61.52μmol/g), hydrogen (58.89μmol/g) and acetone (3.32μmol/g) in triethanolamine (TEA) medium was observed at pH 9 and catalyst dosage 3g/L. It was inferred that AgBr/g-C3N4 composite has the highest photocatalytic activity than that of pure g-C3N4.