Structural correlation of a nanoparticle-embedded mesoporous CoTiO₃ perovskite for an efficient electrochemical...

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 R3̄ 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 MnO₂, and TiO₂.