JSFiddle - React, Tailwind, and code Playground

HTML

<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/font-awesome/4.7.0/css/font-awesome.min.css">
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css">
<a class="btn btn-info btn-lg fa fa-angle-double-down" id="mais-sobre" href="#"></a>

JavaScript

$('#mais-sobre').on('click', function(event){
    event.preventDefault();
    $(this).toggleClass('fa-angle-double-down fa-angle-double-up');
});