H₂ Generation by Cycling Dark Adsorption and Successive Photoinduced Desorption of 2-Mercaptopyridine on/from Ag-Core/Pt-Shell Nanoparticles Loaded on TiO₂

Generation of H₂ with liquid-phase adsorption of a thiol (2-mercaptopyridine, RSH) on transition metal surfaces has been confirmed for the first time. This reaction consists of photoinduced reduction of RS adsorbed on the metal to RSH and its re-adsorption during the subsequent dark process. Nearly perfect overcoating of nanometer-sized Ag particles with Pt by photodeposition (Pt-shell/Ag-core/TiO₂) remarkably increases the rate of H₂ production, and its reproducibility with cycle time is also much improved. X-ray photoelectron spectroscopy has provided clear evidence for the S−H bond cleavage with adsorption of RSH on Ag and Pt-shell/Ag-core particles loaded on TiO₂.