Supercapacitive Behavior of Co3O4 Nanoplates Prepared via Pulse Electrosynthesis Followed by Heat-treatment

Cobalt oxide (Co3O4) with a spinel structure has received considerable attention because of its diverse applications in many fields such as catalysis [1], sensor [2], batteries [3] andsupercapacitors [4-6]. An emerging application of Co3O4 as an electrode material in electrochemical supercapacitors can prove itself as a promising alternate to expensive RuO2, which has been used extensively as electrode material. In the supercapacitive application, thesheet or plate-like structures are beneficial to improvement the electrochemical performance of Co3O4 [5]. These structures can provide large inter-sheet spacing for transferring the ions rapidly and increasing the electroactive material–electrolyte interface area i.e. electrolyte penetrationwhich results high utilization of the electrode materials. In addition to the inter-sheet spacing, the microstructure or morphology of sheets i.e. their thickness and porous nature has an importantrole in electrochemical performance of these structures. It is obvious that the thin and poroussheets can result a high surface area which produces large reaction sites and shortened ion diffusion paths, and a lot of pores cause better electrolyte penetration, respectively.In this work, we applied pulse current in the deposition of hydroxide precursor, and then heattreatment at 400 oC for 3 h. The results showed that the high surface and thin nanoplates are easily achievable. The supercapacitive performance of the prepared nanoplates was evaluated bycyclic voltammetry (CV) and charge-discharge techniques. Fig. 1a shows XRD pattern of theoxide product. The observed peaks in this pattern are fully matched with the corresponding crystalline cubic Co3O4 phase (JCPDS no. 42-1467). No other phase peaks were observed, demonstrating that the deposited hydroxide was completely transformed into Co3O4 after heattreatmentat 400 oC for 3h. SEM observation showed a plate-like structure with regular uniformity (Fig. 1b). Fig. 2 shows the supercapacitive behavior of the prepared nanoplates. The specific capacitances of Co3O4 nanoplates was calculated to be 563.1, 505.8, 437.5 and 388.5 F g–1 at the scan rates of 2, 5, 10 and 25 mV s−1, respectively. These values showed excellent supercapacitive performance of the nanoplates, which resulted from their plate and thin texture, and high surface area

کلیدواژه ها:

Co3O4 ، Pulse electrosynthesis ، Nanoplates ، Supercapacitors