Synergetic photocatalytic-activity enhancement of lanthanum doped TiO2 on halloysite nanocomposites for degradation of organic dye

Abstract

A reusable and efficient photo-catalyst based on halloysites (HNTs) and La3+ ion-doped TiO2nanoparticles was prepared using a sol-gel process and a sonochemical method for decomposingorganic dyes. As a support, the HNTs increased the adsorption efficiency of substrates, improving thephotocatalytic activity of TiO2 nanoparticles by3 times. The La3+ ion doping of TiO2 decreased thebandgap from 3.25 eV to 3.01 eV, expanding the spectral response to the visible region and enhancing thephotocatalytic activity under the sunlight by 1.5 times. Through the integration of the halloysite supportand the La3+ ion doping of TiO2, the synergistic enhancement of photocatalytic activity was observed andsystematically investigated using XRD, Raman spectroscopy, FT-IR, FE-SEM, EDX-TEM, and zeta potential. In this research, we used Rhodamine B molecules as a model pollutant. During the decomposing process,the HNTs enhanced the local dye concentration nearby the photo-catalyst through the electrostaticinteraction, thereby boosting the photocatalytic activity by3 times. Additionally, the catalyst can beseparated by simple centrifugation and reused at leastfive recycles without any activity decrease. Thehalloysite support, the La3+ ion doping of TiO2 and their simple synthesis approach could provide apractical tool for environmental purification in wastewater using sunlight.