电沉积制备MnO2催化剂及其在微生物燃料电池中的应用

通过电沉积的方法获得了一种具有均匀孔隙结构的海绵状二氧化锰催化剂,结合扫描电子显微镜(SEM)、X射线衍射(XRD)、X射线光电子能谱(XPS)等手段表征了所制备材料的表面形貌、结构及元素构成和赋存价态,采用线性伏安扫描(LSV)法对电沉积材料的电化学性能进行分析,考察其催化氧还原反应的活性,最后以合成的材料为阴极催化剂,构建微生物燃料电池系统,考察其在微生物燃料电池中的应用效果。结果表明,以电沉积二氧化锰为阴极催化剂的微生物燃料电池最大功率密度为975.6 mW/m~2,是以商业二氧化锰为阴极催化剂的电池的1.7倍;这表明作为一种经济、高效、环境友好的阴极氧还原催化剂,电沉积法制备的二氧化锰为实现阴极催化剂的低成本制备以及微生物燃料电池放大化推进提供了新的研究途径。

Preparation of MnO2 catalyst by electrochemical deposition and its application in the microbial fuel cells

As a green and clean renewable energy technology, microbial fuel cells (MFCs) have attracted extensive attention. The electrocatalysts with high activity and low-cost towards oxygen reduction reaction (ORR) are of great importance for the large-scale commercial applications of MFCs. Among multifarious cathode catalysts, manganese-based oxides showed high catalytic activity close to that of the precious metals. In this work, a sponge-like manganese dioxide (MnO₂) electro-catalyst was successfully prepared by the electrodeposition method. The surface morphology and composition of as-prepared MnO₂ catalyst were characterized by means of scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and so on; the electrocatalytic activity of the obtained MnO₂ material towards ORR were evaluated by the linear sweep voltammetry (LSV) in a neutral phosphate buffer solution. The results demonstrate that the as-prepared MnO₂ catalyst appears as crystalline γ-MnO₂ and has a high Mn³⁺/Mn⁴⁺ ratio, which is beneficial to improving the catalytic activity in ORR. The as prepared γ-MnO₂ catalyst exhibits superior activity for the ORR under neutral conditions to the commercial MnO₂ catalyst. An MFC coupled with as-prepared catalyst generates an open circuit voltage of 0.52 V, with a maximum power density of 975.6 mW/m², about 1.7 times of that achieved with the MFC using commercial MnO₂ as cathode catalyst, which suggests that the MnO₂ catalyst prepared by the electrodeposition could be an economical alternative for Pt free catalysts in practical application of MFC.