11575
We found that at very high oxygen coverage , obtained at high electrode potentials , the experimentally - observed tetrahexahedral ( THH ) NPs consist of high - index ( 520 ) faces .
 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