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(Invited) How Beneficial Is Reduced Graphene Oxide (RGO) for Long-Term Photo Generated Charge Transport in Inorganic Oxide - Rgo Nanocomposites? a Case Study of Bismuth Titnate - Rgo Films?

Monday, 30 May 2016: 14:20
Aqua 314 (Hilton San Diego Bayfront)
J. Selvaraj (Univ of Nevada), S. Gupta (Univ. of Nevada), S. Fiechter (Helmholtz Zentrum Berlin, Institute for Solar Fuels), and V. Subramanian (University of Nevada, Reno)
This work begins with a summary of the role of reduced graphene oxide (RGO) in promoting the photoactivity of oxides and chalcogenides. Initial indicators suggest that RGO is a good material for promoting charge speration over short time scales. However the story over long term illumination is different. This presentation delineates the results of a systematic analysis of the photoelectrochemical (PEC) and optical responses of RGO combined with a representative multimetal oxide – bismuth titanate (BTO) on films. We investigated the role of RGO as a promoter of charge separation and transport, by suppressing recombination loss of carriers in BTO. The micro-structure of the BTO/RGO composite observed using transmission, scanning electron, and atomic force microscopy, revealed a well-integrated, and highly porous morphology compared to pristine BTO film. The integration of BTO with RGO resulted in a ~ 7 fold increase in photocurrent density with an optimal RGO loading of 2 wt%. The performance of the BTO/RGO interface was further examined to obtain critical insights on: (i) how the electrolyte influences the stability of the BTO/RGO composite and (ii) what interactions prevail at the BTO/RGO interface, under long-term illumination to impact the RGO stability. This work assumes immediate significance because implementation of RGO as a charge transport agent in oxidative systems is heavily researched currently. Unless a mechanism to protect RGO is determined, its long-term stability, especially under oxidative conditions of any form, has to be thoroughly investigated on a case-to-case basis to ensure composite longevity.