A facile and cost-effective single-step pyrolysis approach using a single precursor is introduced to fabricate boron-doped carbons (BDC700 and BDC900) and phosphorus or boron selective-doped-graphenes (PDG700 and BDG900) without using a template, solvent, or catalyst. By increasing the temperature from 700 °C to 900 °C, the tuning of the boron doping level was found in BDCs, and tuning of doping level and selection of heteroatom were possible in PDG700 and BDG900. BDC900, PDG700, and BDG900 were found to have the ability to reduce oxygen directly to water with a four-electron oxygen reduction pathway in an alkaline medium. All four catalysts exhibited excellent stability and resistance to methanol oxidation and CO poisoning. BDCs, PDG700, and BDG900 are a promising alternative to conventional Pt-based catalysts as metal-free catalysts for oxygen reduction reaction in alkaline fuel cells. ⓒ 2013 DGIST
Table Of Contents
I. Introduction 1 -- 1.1 Motivation 1 -- 1.2 Objectives 3 -- II. Theoretical background 4 -- 2.1 Fuel cells 4 -- 2.1.1 Fuel cell fundamentals 4 -- 2.1.2 Oxygen reduction reaction (ORR) 12 -- 2.2 Heteroatom-doped carbon 16 -- 2.2.1 Properties 16 -- 2.2.2 Synthetic approaches 20 -- 2.3 Graphene 22 -- 2.3.1 Properties 23 -- 2.3.2 Applications 25 -- III. Experimental 26 -- 3.1 Preparation of electrocatalysts 26 -- 3.1.1 Boron-doped carbon and their references 26 -- 3.1.2 Phosphorus or boron-selective-doped graphene and their references 26 -- 3.2 Characterization 30 -- 3.2.1 Thermo-gravimetric analysis (TGA) 30 -- 3.2.2 Electron microscope study 30 -- 3.2.3 X-ray diffraction (XRD) study 30 -- 3.2.4 Raman spectroscopic study 31 -- 3.2.6 Electrochemical study 31 -- 3.2.7 Selectivity study: methanol oxidation tolerance and CO poisoning test 33 -- 3.2.8 Durability test 35 -- IV. Results and discussion 37 -- 4.1 Boron-doped carbon 37 -- 4.1.1 Thermo-gravimetric analysis (TGA) 37 -- 4.1.2 Electron microscope study 39 -- 4.1.3 X-ray diffraction (XRD) study 42 -- 4.1.4 Raman spectroscopic study 43 -- 4.1.5 X-ray photoelectron spectroscopic (XPS) study 45 -- 4.1.6 Electrochemical study 48 -- 4.1.7 Selectivity and durability study 54 -- 4.2 Phosphorus or boron-selective-doped graphene 57 -- 4.2.1 Thermo-gravimetric analysis (TGA) 57 -- 4.2.2 Electron microscope study 59 -- 4.2.3 X-ray diffraction (XRD) study 62 -- 4.2.4 Raman spectroscopic study 64 -- 4.2.5 X-ray photoelectron spectroscopic (XPS) study 66 -- 4.2.6 Electrochemical study 70 -- 4.2.7 Selectivity and durability study 75 -- V. Conclusion 78 -- References 79 -- 요약문 87
Research Interests
Electrocatalysts for fuel cells; water splitting; metal-air batteries; Polymer electrolyte membranes for fuel cells; flow batteries; Hydrogen generation and utilization