CeO2-TiO2 FOR PHOTOREDUCTION OF CO2 TO METHANOL UNDER VISIBLE LIGHT: EFFECT OF CERIA LOADING

Abstract

A visible light-driven photocatalyst, CeO 2 -TiO 2 catalyst with different ceria loading was synthesized by impregnation method between TiO 2 powder and cerium oxide nanoparticles slurry. The prepared catalyst samples were characterized by X-ray diffraction (XRD), surface area analysis, UV-vis absorption spectroscopy and photoluminescence spectroscopy (PL). The band gap of CeO 2 -TiO 2 catalyst was found to be 2.15 -2.4 eV. The band gap reduction clearly indicated the successful loading of CeO 2 on TiO 2 . The photocatalytic activity was determined by measuring the photoreduction of CO 2 to methanol in aqueous solution under visible light. The effect of cerium loading in the range of 1 to 5 wt% on the photocatalytic activity was studied and 2 wt% CeO 2 -TiO 2 was found to exhibit the maximum photoactivity of 18.6 µmol/g.catalyst after 6 hours irradiation. Results showed that the prepared photocatalyst is visible light active and may be used as effective catalyst in photoreduction of CO 2 to methanol.Keywords: metal oxide, photocatalyst, band gap, nanoparticles Abstrak Fotomangkin yang boleh diaplikasi di bawah radiasi cahaya nampak iaitu mangkin CeO 2 -TiO 2 yang berbeza muatan ceria telah disintesis dengan kaedah impregnasi serbuk titanium dioksida dengan mendakan partikel nano cerium dioksida. Ciri mangkin yang dihasilkan dikaji dengan menggunakan pembelauan sinar-X (XRD), analisis luas permukaan, UV-Vis spektrofotometer dan spektroskopi fotoluminesen (PL). Jurang tenaga mangkin CeO 2 -TiO 2 adalah di antara 2.15 eV hingga 2.4 eV. Pengurangan jurang tenaga jelas menunjukkan pemuatan CeO 2 ke atas TiO 2 telah berjaya. Aktiviti fotopemangkinan ditentukan melalui tindak balas penurunan gas karbon dioksida (CO 2 ) di dalam larutan akueus kepada metanol dan dijalankan di bawah radiasi cahaya nampak. Kesan pemuatan 1 hingga 5 peratus berat cerium ke atas TiO 2 terhadap aktiviti fotopemangkinan telah dikaji dan CeO 2 -TiO 2 dengan 2 peratus berat cerium didapati menunjukkan fotosensitiviti maksimum iaitu penghasilan 18.6 µmol/g.mangkin selepas 6 jam radiasi. Hasil kajian menunjukkan bahawa fotomangkin yang dihasilkan adalah aktif di bawah cahaya nampak dan dijangka efektif untuk penurunan CO 2 kepada metanol.Kata kunci: logam oksida, fotomangkin, jurang tenaga, partikel nano

Effect of CeO2 content in morphology and optoelectronic properties of TiO2-CeO2 nanoparticles in visible light organic degradation

“…Anatase TiO 2 presents a band gap indirect transition, but fluorite CeO 2 displays a direct transition. In literature reviewed, some authors took direct or indirect transition interchangeably [38,39,46,48,52]. However, there is a marked difference between band gap values depending on electronic transition considered (Fig.…”