30268
Ag nanoparticles of ~ 20 nm size and rather uniform size distribution were synthesized in polyelectrolyte multilayers ( PEMs ) via an ion - exchange / reduction process in two stages ( seeding and growth ) , which were used as sacrificial templates to fabricate Ag - Au bimetallic hollow nanoparticles via galvanic replacement reaction .
 Chemical: Ag; Chemical: Ag - Au
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: Ag; Chemical: Ag - Au