hexo-theme-icarus/layout/_partial/post/category.ejs

<% if (post.categories && post.categories.length){ %>
  <div class="article-category">
  	<i class="fa fa-folder"></i>
    <%- list_categories(post.categories, {
      show_count: false,
      class: 'article-category',
      style: 'none',
      separator: '<i class="fa fa-angle-right"></i>'
    }) %>
  </div>
<% } %>