Study on optical and electrochemical properties of nanorod TiO2 co-modified with GQDs and Gd2O3:Er3+

In this paper, a composite material GQDs/Gd 2 O 3 :Er 3+ /TiO 2 , was prepared by polyol method and hydrothermal method to improve the catalytic performance of TiO 2 . The composite material is analyzed by XRD, SEM, TEM, XPS, RAMAN, UV–Vis and PEC electrochemical test, combined the DFT theoretical calculation simulation. SEM and TEM results show that spherical GQDs/Gd 2 O 3 :Er 3+ nanoparticles are covered on the surface of TiO 2 nanorods. UV–Vis absorption spectra indicates that GQDs/Gd 2 O 3 :Er 3+ broadens the wavelength range of TiO 2 in the wavelength range of 400–1000 nm. The photocurrent density and the applied bias light-electroconversion efficiency of the electrodes of GQDs/Gd 2 O 3 :Er 3+ /TiO 2 is 3.47 times and 7.6 times as that of pure TiO 2 , respectively. DFT calculations reveal that the band width of GQDs/Gd 2 O 3 :Er 3+ /TiO 2 is decreased by 2.647 eV compared to pure TiO 2 , resulting in an easier transition of electrons from valence band (VB) to conduction band (CB). Photocatalytic tests show that the degradating efficiency of methylene blue (MB) by GQDs can reach 68.52 %, which is higher than that of pure TiO 2 (61.68 %).