Surface-defect tailoring in SnO2 (CNT) nanomaterials via sol-gel routes and its influence on the cycling stability.

We report on the synthesis of SnO2 nanoparticles and SnO2:CNT hybrids, via a one-step solgel method. Herein, we investigate the influence of the synthesis conditions on their physical, chemical, optical and electrochemical properties. The crystalline structure, nanoparticle size and morphology are assessed by X-ray diffraction and transmission electron microscopy. The chemical states are elucidated by X-ray photoelectron and Raman spectroscopies. Their electrochemical behavior is studied by cyclic voltammetry. Overall, an oxygen-poor environment during the synthesis leads to smaller SnO2 nanoparticles, along with an increased number of surface defects. Photoluminescence spectroscopy demonstrates that under an oxygen-poor environment, bridging-oxygen vacancies are more abundant. Additionally, SnO2 nanoparticles containing a higher amount of oxygen vacancies exhibit a higher cycling stability of 90%. The cycling stability is further enhanced in hybrid SnO2:CNT. The electrochemical behavior is corroborated to the surface defects and in turn, the band bending mechanism in SnO2 n-type semiconductor. [ABSTRACT FROM AUTHOR]