Herein, we report on the facile synthesis of nanocomposite consisting of TiO2 and Au nanoparticles (NPs) via a tailored galvanic replacement reaction (GRR). The electrocatalytic activity of the synthesized TiO2/Au nanocomposites for CO2 reduction was investigated in an aqueous solution using various electrochemical methods. Our results demonstrated that the TiO2/Au nanocomposites formed through the GRR process exhibited improved catalytic activities for CO2 reduction, while generating more hydrocarbon molecules than the typical formation of CO in contrast to polycrystalline Au. GC analysis and NMR spectroscopy revealed that CO and CH4 were the gas products, whereas HCOO-, CH3COO-, CH3OH, and CH3CH2OH were the liquid products from the CO2 reduction at different cathodic potentials. This remarkable change was further studied using the density functional theory (DFT) calculations, showing that the TiO2/Au nanocomposites may increase the binding energy of the formed ·CO intermediate and reduce the free energy compared to Au, thus favoring the downstream generation of multicarbon products. The TiO2/Au nanocomposites have high catalytic activity and excellent stability and are easy to fabricate, indicating that the developed catalyst has potential application in the electrochemical reduction of CO2 to value-added products.
Keywords: TiO2/Au nanocomposite; carbon dioxide reduction; catalysis; density functional theory; galvanic replacement reaction.