16449
Electrocatalysis under conditions appropriate for the oxygen reduction reaction ( ORR ) was studied , for samples both in situ with no exposure to laboratory air and with air exposure prior to electrochemical measurements .
 Chemical: oxygen
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: oxygen