Yun‐Chih Lin

H2 evolution rate enhanced by Ag-loading on 25 nm TiO2 anatase nanoparticles (denoted as Ag/TiO2), Ag-loaded on hydrogenated TiO2 NPs (Ag/H:TiO2), as well as by the treatment of both NPs with potassium thiocyanate (KSCN) solution have been systematically investigated in conjunction with quantum-chemical calculations and XANES and EXAFS analyses with synchrotron radiation. We have observed a cumulative enhancement effect of these fabrication processes on solar to hydrogen (STH) conversion using a simulating light source. Ag/TiO2 shows an enhanced visible absorption with 4–5 time increase in H2 evolution over that of TiO2 or H:TiO2 prepared under mild hydrogenation conditions, while Ag/H:TiO2 exhibits an even greater UV–visible absorption, similar to that of AgSCN/H:TiO2, with 3.1 times higher STH than that of Ag/TiO2. The treatment of Ag/TiO2 and Ag/H:TiO2 NPs with 0.1 mM KSCN solution further increases their STHs by 3.6 and 2.8 times, respectively. Optimization of KSCN concentration up to 0.2 mM gave [H2] production rate rise to 2.75 mmol h–1 g–1 under Xe lamp illumination for the AgSCN/H:TiO2 system, which has also been tested for its durability, showing a notable robustness. The observed synergistic effect of TiO2 hydrogenation and SCN treatment of the Ag/H:TiO2 NPs has been corroborated by the results of quantum chemical elucidation of H2 production mechanism and the photocatalytic effects of Ag/H:TiO2 and AgSCN/H:TiO2 NPs revealed by appearances of new sub-band states within the TiO2 bandgap, as well as by the result of XANES and EXAFS analyses which support the electron-pulling effect of the SCN group attached to Ag. Finally, we have also compared the efficacies of H2, HCOOH, and CH3OH as hydrogenation sources at 300 °C and the efficacies of CH3OH, C2H5OH, and sucrose as sacrificial agent to facilitate the separation of the electron from the hole.

The nanosized effects of Pt catalysts in terms of surface coverage, electrochemical response, and reaction kinetics during the electro-catalytic methanol oxidation reaction (MOR) have been extensively investigated by the systematic electrochemical measurements, in situ electrochemical FTIR spectroscopy (EC-FTIRS) technique and Density Functional Theory (DFT) computational approaches. In contrast to bulk Pt, a relatively higher COads coverage on the nanosized Pt catalyst was observed at the end of forward sweep (+1.0 V/RHE) from the in situ EC-FTIR investigations. From the DFT calculations, it was demonstrated that the reaction barrier of COads + OHads → COOHads is higher on the edge site of a Pt55 cluster (55 Pt atoms) than that on the facet site of a slab Pt model. The IR observations resulted from the fact that the electro-catalytic MOR appears to be diffusion-controlled on the bulk Pt catalyst, whereas on the nanosized Pt catalyst, it was kinetic-controlled due to both the higher kinetic barrier of COads + OHads reaction and lower diffusion resistance. The surface coverage models of the electro-catalytic MOR on the bulk and the nanosized Pt catalysts have been reasonably proposed via the combined understanding of the in situ EC-FTIR and DFT computational results. The proposed models can reasonably be further elaborated and explained by the systematic electrochemical measurements.

Abstract The transport properties of the nano‐sized TiO 2 ‐based composite polymer electrolyte (CPE) membrane prepared by a green process were investigated. The ion transport phenomena of the CPE was probed by 7 Li solid state NMR spectroscopy and it was found that the lithium ions exist in different environments and were respectively ascribed to the interactions of lithium ions and ether groups, anions and also nano‐sized TiO 2 particles. Further, the NMR line width become narrowing with temperature suggests that the decrease of ion‐pair interaction in themodified CPE. The NMR data is consistent with the conductivity data observed from impedance spectroscopy as a function of temperature. These results suggest that the CPE could be prepared satisfactorily by a greenmethod in which water was used as a solvent instead of organic solvents like THF. In addition, the developed green method is simple, cost effective and environmentally benign due to the absence of hazardous organic solvents.

Abstract A simple synthesis method is presented to prepare highly ordered novel P‐SBA‐15 materials, which can provide additional BrØnsted acid sites for potential applications in catalysis. The developed materials have been unambiguously characterized by various techniques such as SAXS, nitrogen physisorption, SEM, TEM, 31PNMR and FT‐IR spectroscopy. The SAXS and TEM results revealed well‐ordered hexagonal arrays of mesoporous materials. 31PNMR and EDS results confirmed the incorporation of phosphorous in the SB A‐15 network. The method can provide an efficient way to synthesize high phosphorous content mesoporous silica with ordered structure.