17506
The hydrophobic phase is retained in the interior of the porous nanostructure , and HF ( aq ) attacks only the exposed surfaces of the oxidized porous Si sample , generating a hydrophobic , hydrogen - terminated ( Si - H ) outer layer .
 Chemical: HF; Chemical: Si; Chemical: hydrogen; Chemical: Si - H
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: HF; Chemical: Si; Chemical: hydrogen; Chemical: Si - H