Lewis base and metallic sites cooperatively promotes photocatalytic CO2 reduction in PO43-/Ag-TiO2 hybrids

Solar-driven CO2 photoreduction provides an important avenue for achieving carbon neutrality and fuel production. The application of TiO2 in CO2 reduction is limited due to its restricted surface CO2 adsorption, easy recombination of charge carriers, and insufficient catalytic sites. This study aims to improve those deficiencies and promote the photocatalytic CO2 reduction reaction by modifying with Lewis bases (phosphates, PO 4 3- ) and metallic Ag site into mesoporous TiO2 nanorods (PO43--TiO2-Agx). Compared to pristine TiO2, PO43--TiO2-Ag exhibits enhanced photocatalytic CO2 reduction performance, in which the reaction pathway involves the key intermediates of *HCOO- , CO, and *OCH3 confirmed by in-situ FT-IR. PO 4 3--TiO2 has more surface hydroxyl groups and Ti3+ compared to TiO2, and the addition of Ag significantly increases the surface PO 4 3- groups. PO43-- TiO2 has stronger CO2 adsorption performance than TiO2 because of its more abundant surface hydroxyl groups and larger specific surface area. Ag NPs loading increases the surface PO 4 3- groups, resulting in stronger CO2 adsorption in PO43--TiO2-Ag4. In particular, PO 4 3- modification and the Schottky junction formed between Ag and TiO2 can synergically enhance charge separation and increase the effective active sites on the surface of TiO2. It is demonstrated that Ag and PO43-on the surface of TiO2 prepared via NaH2PO2 hydrothermal treatment play important roles in charge transfer and CO2 adsorption promotion, and synergically accelerates photocatalytic CO2 reduction.