Correlation between composition, electrical and electrochemical properties of LnCo${}_{1-x}$Cr${}_x$O${}_3$ (Ln = Pr, Gd and x = 0, 0.5 and 1) perovskites

Electrical and electrocatalytic properties of two series of double perovskites, LnCo${}_{1-x}$Cr${}_x$O${}_3$ (Ln = Pr, Gd, and x = 0, 0.5 and 1), were investigated and discussed in the light of perovskite composition. Studied perovskites were synthesized by the solution combustion method, and powder XRD patterns showed that all compounds crystallize in the GdFeO${}_3$-structure type. The morphology of perovskite crystals was studied by SEM, whereas obtained microphotographs implied porous microstructure. The conductivity of both perovskite series spanned in the range of semiconductors as revealed from electrical measurements. The electrocatalytic activity toward oxygen evolution reaction, oxidation of hydrogen peroxide, and methanol was studied in alkaline solutions by cyclic voltammetry. The influence of electronic, structural and morphological factors to the electrical and electrocatalytic properties is discussed. The praseodymium series showed higher electrocatalytic activity than the gadolinium one, while the most pronounced activity was detected for PrCoO${}_3$.