Abstract

Photodeposition emerges as a convenient method to synthesize metal particles on semiconductor supports. In this work, we study the photodeposition of Pt on Cu2O-TiO2 composite surfaces employing H2PtCl6 aqueous solution as the precursor and reveal a key role of isoelectric point of oxide surfaces on the Pt photodeposition process. Under the photodeposition conditions, Pt metal particles are facilely photodeposited on TiO2 support; on Cu2O-TiO2 composite supports, the Cu2O surface is positively charged and enriched with photo-excited holes while the TiO2 surface is negatively charged and enriched with photo-excited electrons. This lead to the preferential adsorption of PtCl62− anion precursor on the Cu2O surface of Cu2O-TiO2 composite and the dominant formation of Pt oxide particles on Cu2O surface but few Pt metal particles on TiO2 surface. Consequently, the activity of resulting Pt/Cu2O-TiO2 composite photocatalysts in photocatalytic water reduction decreases as the Cu2O content increases. These results deepen the understanding of photodeposition processes on oxide composite surfaces.

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