how do i get my wordpress website url with Colon ':' ..?

add_action( 'init', function() {

    add_shortcode( 'site_url', function( $atts = null, $content = null ) {
        return site_url();
    });

});

I'm Using The Short Code [site_url] and My Short Code Function Returned https//shad-pro.com/contact-us

How Do I get The Proper Url With Colon :