Facile synthesis of heterostructure CeO2-TiO2 nanocomposites for enhanced electrochemical sensor and solar cell applications

Abstract

Heterostructure CeO2-TiO2 nanocomposites were synthesized by chemical precipitation method in aqueous medium at an ambient atmosphere. In the present study, CeO2-TiO2 nanocomposites were examined for their magnetic behavior, electrochemical sensor and perovskite solar cell applications. The existence of cubic CeO2 and anatase TiO2 phases were confirmed by X-ray diffraction and FT-RAMAN analysis. HR-TEM and SAED pattern revealed the morphology and polycrystalline nature of the nanocomposites with average particle size of 5 nm and found that CeO2 highly encapsulated by the TiO2 nanoparticles. EDX spectra also confirm the existence of Ce, Ti and O elements in the nanocomposites. XPS study has been employed to analyze the chemical composition and oxidation state of CeO2-TiO2 nanocomposites. Magnetic studies performed using vibrating sample magnetometer (VSM) measurements; the CeO2-TiO2 nanocomposites showed a strong ferromagnetic behavior at room temperature. Temperature and field dependence of magnetization curves revealed irrespective magnetic behavior of this system. Electron paramagnetic resonance (EPR) results also confirm the presence of ferromagnetic behavior of the nanocomposites. The electrocatalytic behavior of the CeO2-TiO2 nanocomposites showed the superior sensing performance towards hydrazine (N2H4). The modified electrode showed linear range from 0.016 to 0.7 mM (R2 = 0.997) with a sensitivity of 802.61 μA cm−2 mM−1 and good selectivity for hydrazine detection. Photovoltaic performance was also investigated for pure and CeO2-TiO2 nanocomposites for MAPbI3 perovskite under similar fabrication procedure. Surprisingly, the nanocomposites achieved more than 10% efficiency under ∼60% humidity condition with an active area of 0.25 cm2. This work demonstrates that single CeO2-TiO2 nanocomposites can perform as multi-functional material.