The Applications Of Non-carbon Catalyst Supports In Fuel Cells And Photocatalysis

Three non-carbon catalyst supports (rutile phase Ti0.7W0.3O2, non-stoichiometric TiO2-X and spherical WC) were first synthesized and then platinum nanoparticles were reduced on the catalyst supports by sodium borohydride. Cyclic voltammetry and chronoamperometry were performed to evaluate the ethanol electro-oxidation activity and stability of the three as-prepared electrocatalysts and commercial Pt/C. The electro-oxidation peaks of ethanol on Pt/Tio.7Wo.302, Pt/TiO2-X, Pt/WC and commercial Pt/C appeared at0.619,0.617,0.625and0.645V, and their corresponding peak current densities were22.78,18.37,20.82and17.41mA cm-2. From the chronoamperometry experimental results, it showed that the durabilities of the electrocatalysts for ethanol electro-oxidation were in the order of Pt/WC> Pt/Ti0.7W0.3O2> Pt/TiO2-X> commercial Pt/C. The electrocatalytic activities of the four electrocatalysts were studied at different temperatures and activation energies (Ea) for ethanol oxidation were calculated. It showed that Ea for ethanol oxidation were potential dependent and reached a minimum value at0.60V. There were no obvious difference among the minimum Ea values of the four electrocatalysts, indicating that the catalyst supports did not change the pathway of ethanol oxidation on Pt.The oxygen reduction reaction (ORR) activities of the four electrocatalysts were also studied. It showed that the ORR activities of the electrocatalysts were in the order of Pt/WC> Pt/Ti0.7W0.3O2> Pt/TiO2-X> commercial Pt/C and the ORRs at the electrocatalysts were four-electron reduction processes.Furthermore, a novel composite photocatalyst WC/TiO2was prepared by sol-gel method. The WC/TiO2exhibited much higher photocatalytic activity on phenol degradation than pure TiO2and the optimal WC loading is5wt%. The5wt%WC/TiO2composite photocatalyst photodegraded about95.29%of phenol after240-min irradiation. While at the same condition, pure TiO2degraded only about70.62%of phenol. Degradation of phenol followed the quasi-first-order kinetics on both WC/TiO2and TiO2. The rate constants (k) for phenol degradation in pure TiO2and5wt%WC/TiO2were0.00514and0.01231min-1. By analyzing the intermediates of phenol degradation, we supposed that the photocatalytic degradation mechanism of phenol at WC/TiO2composite photocatalyst was as the same as that of pure TiO2.