TiO2-supported Pt single atoms by surface organometallic chemistry for photocatalytic hydrogen evolution

Abstract

A platinum complex, (CH₃)₂Pt(COD), is grafted via surface organometallic chemistry (SOMC) on morphology-controlled anatase TiO₂ to generate single, isolated Pt atoms on TiO₂ nano-platelets. The resulting material is characterized by FT-IR, high resolution scanning transmission electron microscopy (HRSTEM), NMR, and XAS, and then used to perform photocatalytic water splitting. The photocatalyst with SOMC-grafted Pt shows superior performance in photocatalytic hydrogen evolution and strongly suppresses the backwards reaction of H₂ and O₂ forming H₂O under dark conditions, compared to the photocatalyst prepared by impregnation at the same Pt loading. However, single Pt atoms on this surface also rapidly coalesce into nanoparticles under photocatalytic conditions. It is also found that adsorption of CO gas at room temperature also triggers the aggregation of Pt single atoms into nanoparticles. A detailed mechanism is investigated for the mobility of Pt in the formation of its carbonyls using density functional theory (DFT) calculations.