Orientation-controllable growth of Co3O4 single nanocrystals using a BiCoO3 target by pulsed laser deposition

Abstract

We report a novel route to synthesize Co₃O₄ single nanocrystals using pulsed laser deposition by decomposition of BiCoO₃. The decomposition of BiCoO₃ to Bi₂O₃ and Co₃O₄ at relatively high temperature enables the formation of pure Co₃O₄ phase. The absence of Bi element is confirmed by both X-ray diffraction (XRD) and energy dispersive spectrometer (EDS) measurements. The effects of various PLD growth conditions, including growth rate (2–20 Hz), growth temperature (630–650 °C), O₂ partial pressure (50–200 mTorr) and laser energy density (0.6–1.8 J cm⁻²), on the synthesis of Co₃O₄ nanocrystals were systematically studied. Interestingly, the orientation of Co₃O₄ single nanocrystals can be controlled by changing the growth parameters. It is revealed that the decrease of the laser energy density leads to the preferred orientation of Co₃O₄ single nanocrystals altering from (111) plane to (220), while the high temperature growth favors (400) orientation. The obtained orientation-controllable Co₃O₄ single nanocrystals provide the possibility to study its orientation-dependent physical and chemical properties as catalysts, anode materials and magnetic materials.