29030
Better electrochemical behavior was shown by carbon xerogels in monolith than in microsphere form , but higher gravimetric and volumetric capacitances were found in activated carbon xerogel microspheres than in carbon xerogel monoliths .
 carbon, carbon, carbon
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 carbon, carbon, carbon