Showing papers by "Jeffrey C.S. Wu published in 2011"

Plasmonic Photocatalyst for H2 Evolution in Photocatalytic Water Splitting

Abstract: The effect of surface plasmon resonance (SPR) on the photocatalytic water splitting was studied by employing the photocatalyst, Au/TiO2, to produce renewable solar hydrogen. It is well-known that metal particles on TiO2 can behave as electron traps, retarding the recombination of electron−hole pairs, thereby improving reaction activity. However, the electron trap is not the only mechanism responsible for the photoreaction enhancement. Our experiment on methylene blue photodegradation over Au particles proved that the SPR phenomenon was also involved in the photoreaction enhancement. Furthermore, the photocatalytic water splitting was performed on Au/TiO2 prepared by the photodeposition method. The production of hydrogen was significantly increased because Au particles not only acted as electron traps as well as active sites but also played an important role in the SPR enhancement. The intensified electric field at the interface between the Au particle and the subdomain on TiO2 was illustrated by finite el...

Photocatalytic CO2 reduction using an internally illuminated monolith photoreactor

Abstract: One of the promising solutions to both global climate warming and increasing energy demands is artificial photosynthesis, which can be implemented via the photoreduction of CO2 to produce fuel. A monolith photoreactor was used to increase the amount of catalyst loading due to its multiple channels. The photocatalyst was dip coated using NiO/InTaO4 sol and then calcined at 1100 °C. A uniform NiO/InTaO4 layer was obtained on the top of pre-coated SiO2 sublayer on the internal channels of the monolith. The polymethylmethacrylate (PMMA) optical fibers, after being carved on their surface, could transmit and scatter light to effectively illuminate the catalyst inside the channels of the monolith. Vapor-phase CO2 with H2O was photocatalytically reduced to hydrocarbons by UV or visible-light in a steady-state flow mode. The maximum methanol conversion rate achieved was 0.16 µmol g−1 h−1 with visible-light of 290 klx at 25 °C. The highest rate of acetaldehyde was 0.3 µmol g−1 h−1 which was obtained with a loading of 2.6% NiO by simulated sunlight AM1.5G at 70 °C. More importantly, the quantum efficiency was significantly improved indicating that photon energy was effectively utilized in the monolith reactor, compared with previous optical-fiber reactor.

A green catalyst for biodiesel production from jatropha oil: Optimization study

Abstract: In this study, a simple and solvent-free method was used to prepare sulfated zirconia-alumina (SZA) catalyst. Its catalytic activity was subsequently investigated for the transesterification of Jatropha curcas L. oil to fatty acid methyl ester (FAME). The effects of catalyst preparation parameters on the yield of FAME were investigated using Design of Experiment (DOE). Results revealed that calcination temperature has a quadratic effect while calcination duration has a linear effect on the yield of FAME. Apart from that, interaction between both variables was also found to significantly affect the yield of FAME. At optimum condition; calcination temperature and calcination duration at 490 °C and 4 h, respectively, an optimum FAME yield of 78.2 wt% was obtained. Characterization with XRD, IR and BET were then used to verify the characteristic of SZA catalyst with those prepared using well established method and also to describe the catalyst characteristic with its activity.