19784
It is also experimentally and theoretically demonstrated that chlorine free radicals at low coverage prefer to form a stable charge - transfer complex with graphene , which highly enhances graphene ' s conductivity and simultaneously generates a pseudo - bandgap through noninvasive doping .
 Chemical: chlorine; Chemical: graphene; 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: chlorine; Chemical: graphene; Chemical: graphene