Preparation Of Nitrogen-doped Carbon Nanofibers From Bacterial Cellulose And Their Electrocatalytic Performance For Oxygen Reduction Reaction

Fuel cell, as an energy conversion device, can directly switch chemical energy into electrical energy. In recent years,due to its high energy density, high efficiency, excellent security and environmentally friendly, fuel cell has attracted tremendously attentions. However, the oxygen reduction reaction(ORR), occurred in the cathode of fuel cell, is kinetically sluggish and usually requires electrocatalysts to reduce the overpotential. Thus, the development of efficient and inexpensive electrocatalysts for ORR is essential to tackle this issue. In this paper, the high performance electrocatalysts including N-CNFs and Pt/N-CNFs have been synthesized by simple method using bacterial cellulose as precursor. The as-prepared samples were characterized by X-ray diffraction(XRD), transmission electron microscopy(TEM),scanning electron microscopy(SEM) and X-ray photoelectron spectroscopy(XPS), N2 absorption-desorption and electrochemical measurements. The nanostructure, morphology, formation mechanism and the catalytic activity for ORR of these materials also have carefully been investigated.(1) The BC@PPy composite was successfully prepared via in-situ polymerization by using cheap bacterial cellulose as a precursor and ferric chloride hexahydrate as oxidant. And then nitrogen doped carbon nanofibers(N-CNFs) with partial graphitization structure was finally obtained by carbonizing the BC@PPy at 800℃. The SEM and TEM images of N-CNFs showed that N-CNFs possess unique porous 3D network structure which was good for the rapid transfer of the electrons. The electrochemical results revealed that as-prepared N-CNFs exhibited remarkable catalytic activities toward ORR with comparable onset potential and limiting current density of commercial Pt/C catalysts in both alkaline and acid media. The high catalytic activity may be attributed to the unique porous 3D network structure and N-dopant, especially pyridinic-N.(2) N-CNFs were successfully prepared via carbonized(800℃) BC@PANI composite which was synthesized by simple method with using cheap bacterial cellulose as a precursor and ammonium peroxydisulfate as oxidant. Then Pt/N-CNFs were finally obtained by microwave assisted method. The obtained materials were investigated by LSV and Tafel plot. Electrochemical results showed that Pt/N-CNFs revealed a more excellent ORR catalytic property compared with N-CNFs and CNFs, and good electrochemical stability.