Synthesis and characterization of TiO2 supported Pd-Ag bimetalic nanoclusters and investigation of their photocatalytic performance in the decomposition reaction of formic acid

In this study, bimetal PdAg nanoclusters supported on TiO2 were reproducibly prepared in an aqueous solution using an impregnation-reduction technique. The results showed that PdAg bimetallic nanoclusters with an average particle size of 4.8 ± 0.37 nm were appropriately distributed on the TiO2 surface. The TiO2 supported PdAg nanoclusters were used as heterogeneous catalysts in the photocatalytic dehydrogenation of formic acid under visible light (Xe lamp, 300 W) and offered great potential as a safe and suitable hydrogen carrier for fuel cells under ambient conditions. We found PdAgTiO2 to be a highly selective (~99%) and active catalyst able to catalyze the photocatalytic dehydrogenation of formic acid at 22˚C. More importantly, its activity in the photocatalytic dehydrogenation of formic acid in a light environment increased 1.92 times compared to a dark environment and the exceptional stability of the PdAg/TiO2 catalyst against agglomeration, leakage and CO poisoning makes it a reusable photocatalyst in the formic acid dehydrogenation of this catalyst. The PdAg/TiO2 photocatalyst provides an initial TOF value of 371.5 that did not change (~99%) even in the 3rd run. Bimetalic nanoclusters were identified using advanced analytical methods (i.e., XPS, XRD, TEM, HR-TEM, TEM-EDX, ICP-OES). We also derived the rate equation and activation parameters (Ea, ∆H# and ΔS#) depending on temperature and the concentrations of [catalyst], [substrate], [HCOONa] for the kinetic data of the dehydrogenation of formic acid catalyzed by PdAg/TiO2.