Oxygen vacancies induced variations in structural, optical and dielectric properties of SnO 2 /graphite nanocomposite Zulfiqar 1,2 , Sardar Ali Khan 1 , Nasir Rahman 1,3, * , Tahirzeb Khan 2 , RajWali Khan 2 , Majid Khan 2 , Sufaid Shah 1 , Shahid Ali 4 , Hua Tang 1, *, Shahid Hussain 1 , Mudasser Husain 5 , and Muneeb Ur Rehman 6 1 School of Material Science, Engineering, Jiangsu University, Zhenjiang 212013, China 2 Department of Physics, Abdul Wali Khan University, Mardan, KP 23200, Pakistan 3 Department of Physics, University of Lakki Marwat, Lakki Marwat, KP 28420, Pakistan 4 Department of Physics, University of Peshawar, Peshawar, KP, Pakistan 5 Department of Physics, Kohat University of Science & Technology, Kohat, KPK 26000, Pakistan 6 Department of Physics, Islamia College Peshawar, Peshawar, Pakistan Received: 14 February 2020 Accepted: 17 November 2020 Published online: 3 January 2021 Ó Springer Science+Business Media, LLC, part of Springer Nature 2021 ABSTRACT Oxygen vacancies (O.Vs) play vital role in tailoring structural, optical and dielectric properties of nanostructures. Here we prepared SnO 2 /graphite (SG) nanocomposite by growing SnO 2 nanoparticles on graphite sheets via hydrothermal method. Enhanced dielectric behavior due to increase in the oxygen vacancies (O.Vs) has been observed in SnO 2 /graphite (SG) nanocom- posite synthesized. To reveal the underlying origin here, we investigated the structural, morphological, optical, electrochemical and dielectric properties. The growth of SnO 2 NPs on graphite sheets resulted in small-sized NPs (Average size 10.89 ± 0.24 nm) inducing stresses in the structure causing large defect density (O.Vs). The formation of SG nanocomposite has been validated via SEM, TEM, EDX and FTIR. EDX, XPS and Photoluminescence (PL) spectra of SG nanocomposite manifest the presence of large oxygen vacancies (O.Vs). It is revealed that the bandgap of the host material SnO 2 (from ultra violet to the visible window) can be engineered by controlling the assimilation of SnO 2 NPs on GNs. SG nanocomposite exhibits reversible redox process with high anodic and cathodic currents, low internal (0.47 X) and charge transfer (4.08 X) resis- tances, correspondingly, low voltage drop (IR) 0.56 V and high capacitance 54.8 F/g. Variations in dielectric constant (e), dielectric loss (e 00 ) and conductivity (r ac ) are attributed to the increased concentration of O.Vs and introduction of conductive carbon (graphite). The variations in dielectric properties are attributable to Maxewell–Wagner interfacial polarization and hopping process. Address correspondence to E-mail: 11626070@zju.edu.cn; huatang79@163.com https://doi.org/10.1007/s10854-020-04912-4 J Mater Sci: Mater Electron (2021) 32:1402–1412