18530
Vapor - solid growth of high optical quality MoS 2 monolayers with near - unity valley polarization .
 Chemical: MoS 2
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: MoS 2 
Answer:
 Chemical: MoS 2