Green synthesis nanokomposit ZnO/CeCuO3 menggunakan ekstrak daun bunga matahari (Helianthus annuus L.) dan uji aktivitas fotokatalitiknya terhadap malasit hijau = Green synthesis ZnO/CeCuO3 nanocomposites mediated by sunflower leaf extract (Helianthus annuus L.) and its photocatalytic activity of malachite green dye