Unveiling the key factors affecting the grain size of NiCo2O4 during electrodeposition

Abstract

NiCo2O4 bimetallic oxides are extraordinary ideal choice for supercapacitor electrode materials. As is widely known, the electrochemical properties of NiCo2O4 are strongly affected by its morphology. Then, how to obtain NiCo2O4 with ideal morphology has become a hot topic. In this paper, we found that the deposition rate ratio of Co2+ and Ni2+ is a decisive factor influencing the nucleation and growth of NiCo2O4 by the electrodeposition synthesis. When the deposition ratio of Co2+ and Ni2+ is close to 2.5:1, the nucleation rate of NiCo2O4 increases. NiCo2O4 nanoflakes with thinner and smaller morphology can be obtained. What’s more, we found that the deposition rate ratio of Co2+ and Ni2+ depends on the temperatures. Especially, the deposition rate ratio of Co2+ and Ni2+ can approach 2.5:1, when the electrodeposition temperature is 10 ℃. The obtained NiCo2O4 flower cluster nanosheets exhibited an outstanding capacitance of 1590 F·g−1 at the current of 1 A·g−1 and 1080 F·g−1 at the current of 20 A·g−1. More importantly, a large reversible capacitance of 1288 F·g−1 with a capacitance retention of 81.0 % can be obtained after 10,000 cycles at 1 A·g−1.