(中南大學(xué) 化學(xué)與化工學(xué)院，長(zhǎng)沙 410083)
摘 要: 以Co(CH3COO)2·4H2O為鈷源，聚乙二醇(PEG)20 000為表面活性劑，在水−正丁醇溶劑體系中，分別以氫氧化鉀、碳酸銨和草酸為沉淀劑，采用沉淀法制備氫氧化鈷、堿式碳酸鈷和草酸鈷前驅(qū)體。氫氧化鈷前驅(qū)體于160 ℃通過(guò)水熱氧化法，可制得立方體狀四氧化三鈷(Co3O4)；堿式碳酸鈷和草酸鈷前驅(qū)體采用水熱−熱分解法分別于 450 ℃和400 ℃煅燒3 h可制得球鏈狀和棒狀Co3O4。用熱重分析、紅外光譜、X射線衍射和透射電鏡對(duì)所制得前驅(qū)體和產(chǎn)物Co3O4的形貌和結(jié)構(gòu)進(jìn)行表征，并對(duì)所制備的不同形貌Co3O4進(jìn)行電化學(xué)性能測(cè)試。研究結(jié)果表明：產(chǎn)物Co3O4的形貌與其前驅(qū)體和制備方法有關(guān)，當(dāng)采用氫氧化鈷前驅(qū)體可制備平均晶粒度約為15 nm的立方體狀Co3O4；當(dāng)采用堿式碳酸鈷和草酸鈷前驅(qū)體可分別制得直徑約為40 nm、長(zhǎng)約為100 nm的球鏈狀Co3O4和直徑約為0.1 μm、長(zhǎng)度可達(dá)1 μm的棒狀Co3O4。通過(guò)對(duì)不同形貌的Co3O4進(jìn)行循環(huán)充放電測(cè)試，可知納米級(jí)Co3O4的電化學(xué)性能優(yōu)于微米級(jí)Co3O4的；立方體狀Co3O4的電化學(xué)性能優(yōu)于其他形貌Co3O4的電化學(xué)性能，其循環(huán)10次后的充電比容量為406 mA∙h/g。
關(guān)鍵字: 四氧化三鈷；前驅(qū)體；形貌；水熱法；熱分解；電化學(xué)性能
（School of Chemistry and Chemical Engineering, Central South University, Changsha 410083, China）
Abstract:The Co(OH)2, Co2(OH)2CO3 and CoC2O4 precursors were prepared by precipitation method using Co(CH3COO)2·4H2O as cobalt source, polyethylene glycol(PEG) 20 000 as surfactant, water−n-butanol as solvent system, and KOH, (NH4)2CO3 and H2C2O4·2H2O as precipitating agent, respectively. The nanocubic Co3O4 was synthesized through Co(OH)2 precursor at 160 ℃ by hydrothermal oxidation method. The catenuliform-like and rod-like Co3O4 powders were obtained when Co2(OH)2CO3 and CoC2O4 precursors were calcined at 450 ℃ and 400 ℃ for 3 h by hydrothermal−thermal decomposition method, respectively. The morphology and structure of precursor and Co3O4 product were characterized by thermogravimetry(TG), infrared(IR) spectrum, X-ray diffractometry(XRD) and transmission electron microscopy(TEM). The electrochemical performance of as-prepared Co3O4 with different morphologies was tested. The results show that the morphologies of Co3O4 change with the precursors prepared using different precipitating agents and methods. The cubic Co3O4 with particle size of 15 nm can be obtained using Co(OH)2 as precursor, and catenuliform-like Co3O4 with about 40 nm in diameter and 100 nm in length and rod-like Co3O4 with about 0.1 μm in diameter and 1 μm in length can be obtained using Co2(OH)2CO3 and CoC2O4 as precursors, respectively. The electrochemical performance of nano-Co3O4 is superior to that of micro-Co3O4. The cubic Co3O4 shows the best electrochemical performance in all the as-prepared Co3O4 samples, and its specific charge capacity retains 406 mA∙h/g after 10 discharge-charge cycles.
Key words: Co3O4; precursor; morphology; hydrothermal method; thermal decomposition; electrochemical performance
