Pada penelitian ini, sintesis nanokomposit ZnO/CeMnO
3 dilakukan dengan metode
green synthesis menggunakan ekstrak daun bayam raja (
Amaranthus viridis). Metabolit sekunder pada ekstrak digunakan sebagai basa lemah dan
capping agent dalam proses sintesis nanokomposit. Untuk mengidentifikasi sifat optik dan struktural nanopartikel serta nanokomposit, dilakukan dikarakterisasi dengan instrumen UV-Vis DRS, FTIR, XRD, Photoluminescence, SEM-EDX, dan HRTEM. Nanokomposit ZnO/CeMnO
3 menunjukkan nilai
band gap yang menurun dibanding ZnO, yaitu pada 2,68 eV. Selain itu, karakterisasi HRTEM mengkonfirmasi terbentuknya ZnO/CeMnO
3 heterojunction dengan
d spacing ZnO (110) = 0,162 nm dan
d spacing CeMnO
3 = 0,31 nm. Ukuran partikel rata-rata ZnO/CeMnO
3 adalah 7,46 nm. Aktivitas fotokatalitik nanokomposit ZnO/CeMnO
3 diuji untuk mendegradasi larutan malasit hijau di bawah sinar tampak selama 120 menit serta dibandingkan dengan aktivitas fotokatalitik nanopartikel ZnO dan CeMnO
3. Persentase fotodegradasi malasit hijau oleh ZnO/CeMnO
3, CeMnO
3, dan ZnO masing-masing bernilai 92,69%; 69,46%; dan 37,5%. Kinetika reaksi fotodegradasi nanokomposit ZnO/CeMnO
3 mengikuti model orde satu semu dengan konstanta laju senilai 1,031 x 10
-2 min
-1. Peningkatan aktivitas fotokatalitik nanokomposit ZnO/CeMnO
3 disebabkan karena adanya penurunan bandgap ZnO dan rendahnya laju fotorekombinasi
electron-hole yang masing-masing dibuktikan oleh analisis spektroskopi UV-Vis DRS dan
photoluminescence.
In this study, ZnO/CeMnO3 nanocomposites were synthesized using green synthesis method using green amaranth leaf extract (Amaranthus viridis). The secondary metabolites present in the extract were utilized as a weak base and capping agent during the synthesis processes. To identify the optical and structural properties of the synthesized nanoparticles and nanocomposites, characterization was performed using UV-DRS, FTIR, XRD, Photoluminescence, SEM-EDX, and HRTEM instruments. The synthesized ZnO/CeMnO3 nanocomposite showed a decreased band gap value compared to ZnO, at 2,68 eV. Additionally, XRD and HRTEM characterization confirmed the formation of the ZnO/CeMnO3 composite on a nanometer scale with the average particle size at 7,46 nm. The photocatalytic activity of the ZnO/CeMnO3 nanocomposite was tested by degrading a malachite green solution under visible light for 120 minutes and compared with the photocatalytic activity of ZnO and CeMnO3 nanoparticles. The percentages of malachite green photodegradation by ZnO/CeMnO3, CeMnO3, and ZnO were 92,69%; 69,46%; and 37,5%, respectively. The photodegradation reaction kinetics of the ZnO/CeMnO3 nanocomposite were also determined to follow a pseudo-first-order model with a rate constant of 1.031 x 10-2 min-1. The increase in photocatalytic activity of the ZnO/CeMnO3 nanocomposite is due to a decrease in the bandgap and a low rate of electron-hole photorecombination which is proven by UV-Vis DRS and photoluminescence analysis respectively.