Issue 32, 2015

M–Au/TiO2 (M = Ag, Pd, and Pt) nanophotocatalyst for overall solar water splitting: role of interfaces

Abstract

M–Au/TiO2 (M = Ag, Pd, Pt) composites were prepared through a facile one-pot photodeposition synthesis and evaluated for solar water splitting (SWS) with and without a sacrificial agent. The M–Au combination exhibits a dominant role in augmenting the H2 generation activity by forming a bi-metallic system. Degussa P25 was used as a TiO2 substrate to photodeposit Au followed by Au + M (M = Ag/Pd/Pt). The SWS activity of the M–Au/TiO2 was determined through photocatalytic H2 production in the presence of methanol as a sacrificial agent under one sun conditions with an AM1.5 filter. The highest H2 yield was observed for Pt0.5–Au1/TiO2 and was around 1.3 ± 0.07 mmol h−1 g−1, with an apparent quantum yield (AQY) of 6.4%. Pt0.5–Au1/TiO2 also demonstrated the same activity for 25 cycles of five hours each for 125 h. Critically, the same Pt0.5–Au1/TiO2 catalyst was active in overall SWS (OSWS) without any sacrificial agent, with an AQY = 0.8%. The amount of Au and/or Pt was varied to obtain the optimum composition and it was found that the Pt0.5–Au1/TiO2 composition exhibits the best activity. Detailed characterization by physico-chemical, spectral and microscopy measurements was carried out to obtain an in-depth understanding of the origin of the photocatalytic activity of Pt0.5–Au1/TiO2. These in-depth studies show that gold interacts predominantly with oxygen vacancies present on titania surfaces, and Pt preferentially interacts with gold for an effective electron–hole pair separation at Pt–Au interfaces and electron storage in metal particles. The Pt in Pt0.5–Au1/TiO2 is electronically and catalytically different from the Pt in Pt/TiO2 and it is predicted that the former suppresses the oxygen reduction reaction.

Graphical abstract: M–Au/TiO2 (M = Ag, Pd, and Pt) nanophotocatalyst for overall solar water splitting: role of interfaces

Supplementary files

Article information

Article type
Paper
Submitted
06 Jun 2015
Accepted
30 Jun 2015
First published
06 Jul 2015

Nanoscale, 2015,7, 13477-13488

M–Au/TiO2 (M = Ag, Pd, and Pt) nanophotocatalyst for overall solar water splitting: role of interfaces

A. A. Melvin, K. Illath, T. Das, T. Raja, S. Bhattacharyya and C. S. Gopinath, Nanoscale, 2015, 7, 13477 DOI: 10.1039/C5NR03735B

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