14865
We demonstrate a significant tunability in the work function of rGO up to 2 . 5 eV by altering the composition of oxygen - containing functional groups for a fixed oxygen concentration , and of the photoluminescence emission by modulating the fraction of epoxy and carbonyl groups .
 Chemical: rGO; Chemical: oxygen; Chemical: oxygen; Chemical: epoxy; Chemical: carbonyl
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: rGO; Chemical: oxygen; Chemical: oxygen; Chemical: epoxy; Chemical: carbonyl