9001
We investigated the effect of the hydrogenation of graphene to graphane on its mechanical properties using first - principles calculations based on density - functional theory .
 Chemical: graphene; Chemical: graphane
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
 Entities: graphene, graphane 
Answer:
 Chemical: graphene; Chemical: graphane