$baslangic = strtotime('09:00');
$bitis = strtotime('23:00');

$saatler = [];

for($i = 3600; $i < $bitis - $baslangic; $i += 3600) {
  array_push($saatler, date('H:i', $baslangic + $i));
}

print_r($saatler);