(1. 吉首大學(xué) 生物資源與環(huán)境科學(xué)學(xué)院，吉首 416000；
2. 湖南省2011計(jì)劃“錳鋅釩產(chǎn)業(yè)技術(shù)”協(xié)同創(chuàng)新中心，吉首 416000)
摘 要: 以高錳酸鉀、草酸錳、石墨烯為原料，采用化學(xué)共沉淀法制備MnO2@graphene 復(fù)合材料，用X射線衍射、紅外光譜、拉曼光譜、掃描電鏡、比表面測定等對其進(jìn)行表征。以MnO2@graphene為MFC陰極氧還原反應(yīng)催化劑，采用循環(huán)伏安法和電化學(xué)阻抗法研究MnO2@graphene催化電極對氧還原反應(yīng)的催化活性。結(jié)果表明：粒度為400 nm左右的MnO2顆粒通過靜電相互作用均勻而牢固地分散在紙片狀graphene表面，形成MnO2@graphene復(fù)合材料。循環(huán)伏安測試結(jié)果表明：當(dāng)掃描速率為5 mV/s時(shí)，雖然MnO2@graphene催化電極在pH為7.0的磷酸鹽緩沖體系(PBS)的氧還原反應(yīng)起峰電位比Pt/C催化電極負(fù)0.048V，但其峰電位(-0.440 V)與Pt/C催化電極的起峰電位(-0.434 V)接近。隨著循環(huán)次數(shù)的增加，MnO2@graphene催化電極的起峰電位稍有下降，但峰電流密度下降很小，表明MnO2@graphene催化劑具有更好的氧還原催化活性和更優(yōu)秀的循環(huán)穩(wěn)定性。電化學(xué)阻抗實(shí)驗(yàn)發(fā)現(xiàn)：MnO2@graphene催化電極的電荷轉(zhuǎn)移阻抗為12.6 Ω，比同條件下Pt/C催化電極和MnO2催化電極的低，表明由于graphene增加MnO2的導(dǎo)電性，降低催化電極電荷轉(zhuǎn)移阻抗，加快電子的轉(zhuǎn)移速率，促進(jìn)陰極氧還原反應(yīng)。
關(guān)鍵字: 二氧化錳；石墨烯；氧還原反應(yīng)；催化活性；微生物燃料電池
（1. College of Biology and Environmental Sciences, Jishou University, Jishou 416000, China;
2. The Collaborative Innovation Center of Manganese-Zinc-Vanadium Industrial Technology (the 2011 Plan of Hunan Province), Jishou 416000, China）
Abstract:MnO2@graphene composites were prepared by a chemical co-precipitation method using KMnO4, MnC2O4·2H2O and graphene as raw materials.The microstructure, morphology of the prepared composites were analyzed using X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectrum, Raman spectroscopy, X-ray photoelectron spectroscopy(XPS), scanning electron microscopy (SEM) and specific area measurements. The electrochemical performances of MnO2@graphene composites as catalysts for cathodic oxygen reduction reaction in microbial fuel cell were analyzed using cyclic voltammetry, electrochemical impedance spectrometry (EIS). The results show that spherical MnO2 with uniform particle size of 400 nm is tightly formed on the surface of paper-like graphene by electrostatic interaction. Moreover, the peak potential of MnO2@graphene electrode (-0.440 V) is very close to that for Pt/C electrode (-0.434 V), though the initial peak potential of MnO2@graphene electrode is 0.048 V negative than that for Pt/C electrode. With the increase of cycling times, the initial peak potential of MnO2@graphene electrode decreases, while there is only a small decline for the peak current density of MnO2@graphene electrode, indicating that the MnO2@graphene composites have better catalytic activity and cycling stability for cathodic oxygen reduction reaction in microbial fuel cell than that for Pt/C catalysts. EIS results show that the electron-transfer resistance of MnO2@graphene is only 12.6 Ω, which is smaller than that for Pt/C catalysts and MnO2 catalysts, suggesting MnO2@graphene catalysts promote the cathodic oxygen reduction reaction by decareasing the electron-transfer resistance and accelerating the charge transfer due the introduction of the excellent conductive graphene.
Key words: MnO2; graphene; oxygen reduction reaction; catalytic activity; microbial fuel cell
