V.P. Malekar’s research while affiliated with Shivaji University and other places

We report the effect of nickel (Ni) ion doping on the structure, morphology, and supercapacitive performance of Mn3O4 thin film electrodes, deposited by a simple electrophoretic deposition technique. The structural and compositional studies of these thin films were conducted by x-ray diffraction and Fourier transform infrared spectroscopy. The morphological and optical properties were investigated by scanning electron microscopy, transmission electron microscopy, and UV–visible spectroscopy. These studies confirmed the nanoflake-type surface morphology of nickel-doped thin films. X-ray photoelectron spectroscopy provided information about various valence states and surface composition of the thin films. Cyclic voltammetry study confirmed the surface redox pseudocapacitive behavior of all thin films. The 2 mol.% nickel ion-doped thin film electrode displayed the highest specific capacitance of 816 F g−1 and was evaluated from the galvanostatic charge/discharge curve. It also exhibited outstanding cyclic stability, with 93% capacitance retention after 2000 cycles. Electrochemical impedance spectroscopy revealed the improved supercapacitive performance of the nickel-doped Mn3O4 thin film electrodes, attributed to improved conductivity and charge transport for surface redox reactions. Thus, the present study suggests that the nickel-doped Mn3O4 thin film is a promising candidate as electrode material in supercapacitors.

The redox additive in an aqueous gel electrolyte is reported as one of the efficient methods to improve the electrochemical supercapacitor performance. Here, we report the role of redox additive, potassium ferricyanide((K3[Fe(CN)6]), referred to as KFCN) for improving the electrochemical performance of binder-free, CuCo2O4 (CCO) nanowire arrays (NWs) based solid state symmetric supercapacitors (SSCs). The crystal structure and morphology of prepared CCO films are confirmed by X-ray diffraction (XRD) and field emission-transmission electron microscopy (FE-TEM). The elemental composition of CCO films is estimated as Cu0.5Co2.77O3.82 via energy-dispersive X-ray spectroscopy (EDS) analysis. Surprisingly, the areal capacitance (or energy density at 5 mAcm−2) is significantly improved from 0.58 F cm−2 (or 0.016 mWh cm−2) to 10.5 F cm−2 (or 0.296 mWh cm−2), respectively, after the addition of KFCN to aqueous KOH electrolyte, as compared to bare KOH. Furthermore, CCO exhibits decent cyclic stability with 90 % capacitance retention up to 5000 CV cycles at the scan rate of 100 mV s−1. Moreover, 2-terminal CCO NWs-based SSCs, employed with PVA-KOH-KFCN gel electrolyte, demonstrate a wider potential window of −0.9 to 0.9 V (1.8 V) with a 7-fold increase of energy density from 9.1 to 65 Wh kg−1, as compared with that of PVA-KOH gel electrolyte. As practical validation, the operation of Red-LED for 3 min is demonstrated with PVA-KOH-KFCN gel-based SSC, manifesting that adding redox substance in aqueous electrolytes is one of the promising strategies for portable and wearable energy storage systems

In this work, the 3D interconnected cobalt oxide nanoflakes (CON) were grown successfully on nickel foam (NF) at ambient conditions by the electrodeposition method, further followed by calcination. The deposition of Co3O4 was carried out for different deposition times of 10 min, 15 min, and 20 min and enumerated as CON-10, CON-15, and CON-20 respectively. The CON samples were characterized for their Physico-chemical studies by XRD, FT-IR, FE-SEM, and EDS. FE-SEM micrographs of CON nanostructures showed the uniform deposition of the 3D interconnected nanoflakes on NF. The sample CON-15 exhibited the highest specific capacitance (Cs) of 444 Fg⁻¹ also the specific energy (SE) of 26.07 Whkg⁻¹, specific power (SP) of 541.66 Wkg⁻¹, and efficiency (ɳ) of 77 % at 1 mAg⁻¹ with outstanding cycling stability of 86 % capacitance retention after 1000 cycles.

Here, cadmium sulfide (CdS) thin films have been prepared by electrodeposition method using aqueous basic electrolyte. The electrodeposition of CdS thin films has been carried out by varying the concentrations. The deposition potential of the compound was studied by cyclic voltammetry. The as-deposited and irradiated CdS thin films were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), and optical absorption technique for different bath concentration. The XRD shows multi crystalline phases having (1 1 0) major peak. The band gap was found to be 2.3 and 2.4 eV was as deposited and irradiated flim. The layers were subjected to irradiation with 6 MeV electrons.

The CuSe thin films are prepared by Electrodeposition method. The structural and optical properties of CuSe thin films are studied by means X-Ray diffraction (XRD) study, Scanning Electron Microscopy (SEM), and UV–Visible absorption study. Optical absorption study is carried out using UV–VIS spectrometer in the wavelength range 350–850 nm of electrodeposited CuSe thin films deposited on FTO coated glass substrate. The optical band gap energy of CuSe thin film varies from 2.4 to 2.6 eV. It has been observed that the electrodeposited films are polycrystalline in nature. Also, it is evident that band gap energy increases by decreasing bath concentration as well as deposition time.

Nanostructure Copper Chalcogenide thin films can be prepared using electrodeposition technique. The structural, morphological and surface wettability properties of the as deposited Copper Selenide thin films have been studied using XRD, SEM and contact angle measurement Optical band gap energy (Eg value) for Copper Selenide thin films ranges from 2.4 eV to 2.6 eV. FT-Raman and FT-IR spectral properties of the deposited films have been studied by FT Raman and FT-IR spectrophotometer. Using as deposited holographic thin films fringe width, thickness of thin film, stress to substrate and mass deposited can be calculated. It is observed that, increase in deposition time thickness of thin film and mass deposited increases but fringe width as well as stress to substrate decreases

Here, the Double Exposure Holographic Interferometry (DEHI) technique is used to study the surface deformation of CdSe films electrodeposited on stainless steel substrate. The electrodeposition of CdSe thin films is carried out by varying the time of deposition. The deposition potential of the compound was studied by cyclic voltammetry. The structural, surface morphological and optical properties of the deposited films have been studied by X-ray diffraction (XRD), scanning electron microscope (SEM) and optical absorption technique respectively. Also the contact angle measurements are carried out. The DEHI technique is used to determine, thickness of thin films, mass deposited, fringe width and stress to substrate of electrodeposited CdSe thin films for various deposition time with different solution concentrations. With increasing deposition time fringe width was decreased due to the reduction in film stress

In this paper, the effects of electron beam irradiation on the CdTe thin films are studied. The CdTe thin films are characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and contact angle measurements for different bath concentration. The thin film layers are subjected to irradiation of 6 MeV electrons. Finally the effect of irradiation is correlated to crystal size, grain size and contact angle measurements of the CdTe thin films