UTC time in PHP

<?php

$zone = "";
$zone = $_GET["zone"];
if ($zone == "") $zone = 'Europe/Rome';

date_default_timezone_set('UTC');
$dt = date('d/m/Y H:i:s');

print '<'.date_convert($dt, 'UTC', 'd/m/Y H:i:s', $zone, 'd/m/Y H:i:s').'>';
//print "<27/10/2016 13:12:02>";

function date_convert($dt, $tz1, $df1, $tz2, $df2) {
  $d = DateTime::createFromFormat($df1, $dt, new DateTimeZone($tz1));
  $d->setTimeZone(new DateTimeZone($tz2));
  return $d->format($df2);
}

?>