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Liu , and co - workers have systematically investigated the influence of specific features of 2D molecules , such as their thickness , stacking order , single - and double - side upon graphene ' s radical reactivity by utilizing a free radical photochlorination as a probe .
 Chemical: graphene
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