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Enhanced photovoltaic performance of a DSSC using graphene - TiO2 photoelectrodes prepared by our recent in situ simultaneous reduction - hydrolysis technique ( Adv . Funct . Mater . , 2012 , DOI : 10 . 1002 / adfm . 201202349 , in press ) was achieved .
 Chemical: graphene; Chemical: TiO2
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 Chemical: graphene; Chemical: TiO2