Metal Nanoshells for Enhanced Solar-to-Fuel Photocatalytic Conversion

Abstract

In our preliminary study, we had prepared quaternary semiconductor powder of Ag x In x Zn y S 2x+y , a photocatalysts with a high activity. In this study, we further extended the investigation, changed the amount of indium in a series of solid solutions, and increased the photochemical activity substantially.With little adjustment of the ratios of [In]/[Ag], the hydrogen production rate of the photocatalysts, Ag x In y Zn z S (x+3y+2z)/2 , are significantly improved. The most enhancement of the activity can go up to four times, compared to our first generation photocatalyst. SEM images show that different amount of nonosteps on the surface relate to the ratios of [In]/[Ag]. These edges of nanosteps are considered as the active sites that facilitate the electron-hole separation, leading to higher solar-to-fuel conversion efficiency. The other ingredient, zinc, is used to control the band gap. Both changes of indium and zinc, we maximized the efficiency of this photocatalyst (970 μmol/h·g). In a separate experiment, the photocatalystic reactions were carried out at elevated temperature. The effect of temperature, typically with addition of Ag@Au NPs (nanoparticles) was evaluated. The presence of metal nanoshells can absorb the solar energy in the IR range. However, the broad absorption of metal nanoshells also covered the visible-light region, which decrease the efficiency of the metal sulfide photocatalysts. The incorporation of metal nanoshells, as well as the nanostructure of photocatalyst will be further investigated. IntroductionOf all known renewable energy sources, solar energy stands as the most abundant and readily accessible. Consider, for example, that the amount of solar energy striking the earth every 40 minutes Report Documentation PageForm Public reporting burden for the collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden, to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to a penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. REPORT DATE SEP 20112. REPORT TYPE Secondly, it was demonstrated that at an elevated temperature, the hydrogen evolution rate is higher. Future study will focus on improving the efficiency of our second-generation photocatalyst, create various core-shell structures, measure the hydrogen production rate, and test the stability of this composite system.