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Titanium based-perovskites have got surprising attraction due to their environmentfriendly photocatalysts behavior. The Rietveld refinement of X-ray diffraction (XRD) pattern authenticates the orthorhombic Pnma structure of Pr2MgTiO6 (PMT). The Pr3+-Ti4+ intervalence charge transfer process plays an important role inside PMT. The dc conductivity shows a change in the hopping mechanism from nearest-neighbor hopping to a variable range hopping due to the activation energy reduction. This change in the hopping mechanism is well supported by both the relaxation time and impedance data in PMT. The constant phase element (CPE) model is utilized to fit impedance plots. The photocatalytic activity of PMT was performed under UV irradiation with the help of degradation kinetics of organic pollutants. Also, the photocatalytic efficiency of recycled and reused PMT finds 91.2% after 5th cyclic runs. The calculated band-gap is found to be 3.58 eV., Comment: 33 pages, 9 figures, 2 tables. arXiv admin note: substantial text overlap with arXiv:1707.02830, text overlap with arXiv:1904.11962

X-ray diffraction pattern and Raman spectrum authenticate the monoclinic P21/n structure of polycrystalline Pr$_2$ZnMnO$_6$ (PZM) synthesized by the solid-state reaction technique. The X-ray photoemission spectrum suggests the existence of oxygen vacancy in PZM, which plays a crucial role in electrical conduction as well as in electrochemical behavior. The existence of two different conduction mechanisms (such as nearest-neighbor hopping (NNH) and Mott variable range hopping (MVRH)) is observed from the investigation of dc conductivity studies, dielectric relaxation, and impedance analysis of PZM. It is found that below 580 K, there is a transition from NNH to MVRH due to the decrease of activation energy. The constant phase element model is used to correlate the Nyquist plot and electric modulus of PZM. The bulk PZM electrode exhibits intercalated pseudocapacitive nature which offers an efficient specific capacitance of 69.14 F/g at a charge and discharge currents of 2 A/g in an aqueous solution of 1 M KOH. The charge storage mechanism of the PZM electrode has been analyzed and discussed., Comment: 45 pages, 12 Figures, 2 Tables