Addressing the competing adsorption bottleneck in photoreduction of CO2 using a hydrophilic-hydrophobic heterojunction photocatalyst

Solar powered conversion / reduction of carbon dioxide into value added chemicals has been identified as one of the foremost challenges for materials science in the 21st century. Despite extensive research, product yield remained low and one of the primary factors has been the issue of competing adsorption of CO₂ and water vapour on the catalyst surface. In this work we employ reduced graphene oxide wrapped TiO₂ nanotubes (TiO₂ - rGO) as a heterojunction photocatalyst and demonstrate that UV irradiation induces hydrophilicity on the TiO₂ surface and, hydrophobicity on the rGO surface. The resulting photocatalyst shows 25 % higher yield of methane over that of untreated photocatalyst. Hence, UV irradiation induced tailoring of the hydrophilicity yields selective adsorption sites for the CO₂ and water vapour leading to a significant enhancement of the methane yield through photocatalytic reduction process.