I had tried to use handshake icons but it doesn't work, below included us the code which I have tried:
<i class="fa fa-handshake-o"></i>
Please help me
Try Your code in w3 school tryit editor
It is link for that https://www.w3schools.com/icons/fontawesome_icons_intro.asp
I think that You are not include the css for font-awesome so include that 'font-awesome.min.css'
This is the sample screen from try it editor