Graphene Bridge for Photocatalytic Hydrogen Evolution with Gold Nanocluster Co-Catalysts

Herein, the UV light photocatalytic activity of an Au₁₀₁NC-AlSrTiO₃-rGO nanocomposite comprising 1 wt% rGO, 0.05 wt% Au₁₀₁(PPh₃)₂₁Cl₅ (Au₁₀₁NC), and AlSrTiO₃ evaluated for H₂ production. The synthesis of Au₁₀₁NC-AlSrTiO₃-rGO nanocomposite followed two distinct routes: (1) Au₁₀₁NC was first mixed with AlSrTiO₃ followed by the addition of rGO (Au₁₀₁NC-AlSrTiO₃:rGO) and (2) Au₁₀₁NC was first mixed with rGO followed by the addition of AlSrTiO₃ (Au₁₀₁NC-rGO:AlSrTiO₃). Both prepared samples were annealed in air at 210 °C for 15 min. Inductively coupled plasma mass spectrometry and high-resolution scanning transmission electron microscopy showed that the Au₁₀₁NC adhered almost exclusively to the rGO in the nanocomposite and maintained a size less than 2 nm. Under UV light irradiation, the Au₁₀₁NC-AlSrTiO₃:rGO nanocomposite produced H₂ at a rate 12 times greater than Au₁₀₁NC-AlSrTiO₃ and 64 times greater than AlSrTiO₃. The enhanced photocatalytic activity is attributed to the small particle size and high loading of Au₁₀₁NC, which is achieved by non-covalent binding to rGO. These results show that significant improvements can be made to AlSrTiO₃-based photocatalysts that use cluster co-catalysts by the addition of rGO as an electron mediator to achieve high cluster loading and limited agglomeration of the clusters.