Fabrication of Heterostructured g-C3N4/Ag-TiO2 Hybrid Photocatalyst with Enhanced Performance in Photocatalytic Conversion of CO2 Under Simulated Sunlight Irradiation

Heterostructured g-C3N4/Ag-TiO2 (CN/AgTi) hybrid catalysts were fabricated through a facile solvent evaporation followed by a calcination process, using graphitic carbon nitride (g-C3N4) and Ag-TiO2 (AgTi) as precursors. The phase compositions, optical properties, and morphologies of the catalysts were systematically characterized. The heterostructured combination of g-C3N4, titania (TiO2) and silver nanoparticles (Ag NPs) resulted in significant synergy for catalytic conversion of CO2 in the presence of water vapor under simulated sunlight irradiation. The optimal CN/AgTi composite with a g-C3N4 to AgTi mass ratio of 8% exhibited the maximum CO2 photoreduction activity, achieving a CO2 conversion of 47 mu mol, CH4 yield of 28 mu mol, and CO yield of 19 mu mol per gram of catalyst during a 3 h simulated sunlight irradiation. Under the experimental conditions, the rate of electron consumption was calculated to be 87.3 mu mol/g center dot h, which was 12.7 times, 7.9 times, and 2.0 times higher than those for TiO2, g-C3N4 and AgTi, respectively. The combination of g-C3N4 and AgTi resulted in more sunlight harvesting for electron and hole generations. Photoinduced electrons transferred through the heterjunction between g-C3N4 and TiO2, and further from TiO2 to Ag NPs with lower Fermi level greatly suppressed the recombination of electron hole pairs, and hence resulted in electron accumulation on Ag NPs deposited on the TiO2 surface in the CN/AgTi. Abundant electrons accumulated on the Ag NPs were further energized by the surface plasmon resonance effect with the aid of visible light. Therefore, the CN/AgTi catalysts exhibited superior catalytic performance in CO2 reduction by water vapor under simulated sunlight irradiation.(C) 2017 Elsevier B.V. All rights reserved.