Influence of Li doping on the morphological evolution and optical & electrical properties of SnO2 nanomaterials and SnO2/Li2SnO3 composite nanomaterials

SnO2 nanomaterials and SnO2/Li2SnO3 composite nanomaterials doped with different Li contents were synthesized via a simple one-step thermal evaporation method. X-ray diffraction patterns showed that with the increase of Li doping, the intensity of Li2SnO3 diffraction peaks gradually increased, while that of SnO2 diffraction peaks gradually decreased. With the increase of Li doping, the width of nanobelts gradually increased, with the morphology changing from banded structure to standard hexagonal sheet structure. The Raman scattering spectra indicated that with the increase of Li doping, the peak of Li2SnO3 at 588.8 cm-1 kept increasing, and the strongest vibration mode A1g in SnO2 gradually weakened. X-ray photoelectron spectroscopy revealed that with the increase of Li doping, the surface electrophilic oxygen species in SnO2/Li2SnO3 composite nanomaterials greatly increased. Under the condition of light irradiation with a wavelength of 505 nm, the bright current of the Li-doped SnO2 samples was higher than the dark current, while that of the SnO2/Li2SnO3 composite nanomaterials was higher than the dark current, which was mainly due to more oxygen vacancies in SnO2/ Li2SnO3 composite nanomaterials than electrons excited by light. Consequently, positive photoconductivity gradually weakened, and even the negative photoconductivity emerged.