Structural correlation of a nanoparticle-embedded mesoporous CoTiO 3 perovskite for an efficient electrochemical supercapacitor.

We synthesized mesoporous cobalt titanate (CTO) microrods via the sol-gel method as an outstanding working electrode for the supercapacitor. The mesoporous CTO microrods were amassed in hexagonal shapes of an average width of ∼670 nm, and were composed of nanoparticles of average diameter ∼41 nm. The well crystalline CTO microrods of the hexagonal phase to the R 3̄ space group possessed an average pore size distribution of 3.92 nm throughout the microrod. The mesoporous CTO microrods with increased textural boundaries played a vital role in the diffusion of ions, and they provided a specific capacitance of 608.4 F g -1 and a specific power of 4835.7 W kg -1 and a specific energy of 9.77 W h kg -1 in an aqueous 2 M KOH electrolyte, which was remarkably better than those of Ti, La, Cr, Fe, Ni, and Sr-based perovskites or their mixed heterostructures supplemented by metal oxides as an impurity. Furthermore, the diffusion-controlled access to the OH - ions (0.27 μs) deep inside the microrod conveyed high stability, a long life cycle for up to 1950 continuous charging-discharging cycles, and excellent capacitance retention of 82.3%. Overall, the mesoporous CTO shows its potential as an electrode for a long-cycle supercapacitor, and provides opportunities for additional enhancement after developing the core-shell hetero-architecture with other metal oxide materials such as MnO 2 , and TiO 2 .