When studying the hydrogen evolution reaction (HER) of a mixture or composite of two different materials, it can be challenging to identify the number of moles that reacted and the active sites of the composite as a whole. However, there are several experimental and theoretical techniques that can be used to address these challenges:

In summary, the number of moles that reacted and the active sites of a composite material for HER study can be determined through a combination of electrochemical analysis, XPS, DFT calculations, and surface-sensitive techniques.

First of all, you need to develop the method to quantify the hydrogen yield in your reaction. This is very difficult and depends on equipment in you lab.