Vol.:(0123456789) 1 3 Applied Physics A ( 2019) 125:288 https://doi.org/10.1007/s00339-019-2581-1 Synthesis and analysing the structural, optical, morphological, photocatalytic and magnetic properties of TiO 2 and doped (Ni and Cu) TiO 2 nanoparticles by sol–gel technique T. Raguram 1  · K. S. Rajni 1 Received: 15 December 2018 / Accepted: 23 March 2019 © Springer-Verlag GmbH Germany, part of Springer Nature 2019 Abstract In the present work, Ni 2+ and Cu 2+ ions are doped with TiO 2 using sol–gel technique. The efects of Ni and Cu doping in TiO 2 matrix are characterized by XRD, Micro-Raman, FTIR, UV–DRS, PL, and FESEM with EDS. Furthermore, it is analyzed for photocatalytic activity and magnetic applications. From XRD analysis, it is observed that the peaks corresponding to the planes match with the JCPDS data [anatase: 89-4203] of TiO 2 . The crystallite size of the doped samples is found to be greater than that of TiO 2 . Micro-Raman analysis shows the confrmation of anatase phase of TiO 2 . FTIR analysis confrms the presence of functional groups which are presented in the prepared samples. From UV–DRS, the band-gap values of TiO 2 and doped TiO 2 (Ni 2+ , Cu 2+ ) are found to be 3.25, 2.48, and 1.25 eV. Photoluminescence (PL) results show an emission edge of Ni- and Cu-doped TiO 2 is red shifted which is due to the vacancies of titanium and oxygen imported subsequently during doping. The surface morphology and the elemental composition of Ni- and Cu-doped TiO 2 nanoparticles are also analyzed. The photocatalytic activity of all the prepared samples are assessed by methylene blue dye as testing pollutant and visible radiation. The test reveals that Cu–TiO 2 , Ni–TiO 2 , and TiO 2 show the degradation efciency of 68.14, 61.04, and 33.32%, thereby showing that the doped TiO 2 are more efcient in degrading the pollutant and can be applied for future photocatalytic applications. From VSM analysis, the saturation magnetization of Ni–TiO 2 and Cu–TiO 2 is found to be weak and can be improved by the synthesis process and the proportion of dopant. 1 Introduction To manipulate the properties and, hence, to obtain the desired functionality of solids, dopants act an important character, particularly in a feld of microelectronics and optoelectronics. Recently, the search for materials which is both the properties of semiconductors and ferromagnetism (FM) has derived into the valuable feld of material sciences to achievement of the spin degrees of freedom for the carrier. Thus, important research is in progress on investigating the promising of spin functionality of induced ferromagnetism in the non-magnetic semiconductors adding dopants of mag- netic ions via dilute concentrations and thereby obtaining diluted magnetic semiconductors (DMS) [1, 2]. DMS exhibit both the semiconducting and the magnetic properties such as ferromagnetism and magnetoelectricity. In DMS, the interaction (exchange) between the electrons and afects the change in magnetic properties, which, in turn, leads to shift in the bandgap [3]. Studies on DMS have been intensifed recently due to their promising applications in spintronics [4]. DMS materials might be components of new technolo- gies such as non-volatile memories, high-speed devices for data handling and reduced power expenditure, and conceiv- ably tiny structures [5–8]. However, many experimental reports show maintain lower temperature, low moment of magnetic ordering [9, 10]. In support of many possible results reported in the literature, DMS has still challenged by the incorporation of dopants which are consistency, possibilities of secondary ferromagnetic phases, and con- tamination issues [11]. The most intensively explored feld of DMS research is the doping of regular III–V or II–VI semiconductors, where the underlying lattice has wurtzite or zinc-blende structure with transition metal ions such as Cr, Mn, Fe, Co, and Ni [12]. In general, the magnetic (3d) ions in DMS materials are located on substitutional and/ or interstitial sites of the semiconducting host [13]. DMSs * K. S. Rajni ks_rajani@cb.amrita.edu 1 Department of Sciences, Amrita School of Engineering, Amrita Vishwa Vidyapeetham, Coimbatore, India