Controllable preparation and application of porous carbon-based electrode materials

Abstract

With the growing demand for energy storage and conversion technologies, porous carbon-based materials (PCMs) have garnered widespread attention due to their excellent electrical conductivity, high surface area (SSA), and good chemical and thermal stability. This study aims to develop PCMs and explore their applications in the field of energy storage and conversion. By carefully selecting carbon precursor and preparation process, I precisely controlled the pore characteristics and composition of PCMs, resulting in the fabrication of PCMs with different morphologies, including heteroatom-doped and porous carbon/transition metal composites. The morphology, structure, composition, and electrocatalytic performance of these PCMs were systematically analyzed. The specific research content and results are as follows: 1). This study focuses on the controlled preparation and electrochemical properties of one-dimensional porous carbon nanofibers (PCFs). Using a silica-assisted method, PCFs were synthesized and their electrocatalytic performance for supercapacitors (SC) were systematically evaluated. Optimal PCFs exhibits a hierarchical porous structure with high SSA (1407 m2 g-1) and suitable nitrogen doping. When used as electrode material for SC, it shows a specific capacitance of 314 F g-1 at 1 A g-1, excellent cycling stability (after 10,000 cycles at 5 A g-1), and 92.5 % capacity retention. In an assembled SC device, the energy density reached 31.9 W h kg-1 in 1M Na2SO4 electrolyte, and two PCF devices in series powered 2.2 V LEDs, demonstrating their practical potential. 2). The study also explores N/Co co-doped hollow porous carbon nanospheres (Co/N@PCS) as electrocatalysts for the alkaline oxygen reduction reaction (ORR), showing a half-wave potential of 0.81 V vs RHE and an onset potential of 0.91 V vs RHE, along with long-term durability in alkaline electrolytes. This work shows that the Co/N@PCS electrocatalyst has great potential in the field of alkaline ORR. 3). Wrinkled surface nitrogen-doped carbon nanotubes (NCTs) were prepared by a green, controllable template method. The optimal NCTs exhibits a high specific capacitance (336 F g-1) and excellent cycling stability (96.1 % capacitance retention after 10,000 cycles) in SC. 4). Additionally, nitrogen-doped porous carbon spheres (NPCS) synthesized by a simple self-template strategy with phenol formaldehyde resin oligomers (resol) serving as the carbon precursor and g-C3N4 as a self-template. The final NPCS possesses a high SSA of 880 m2 g-1, abundant pore structure and suitable nitrogen doping (2.35 %), exhibiting excellent performance as SC electrode material. 5). Porous Carbon nanosheets (PCNs) with adjustable thickness were synthesized by a template method and the electrocatalytic performance differences of PCNs with varying wall thickness were studied. The optimized PCNs, with a rich pore structure, large SSA, and moderate wall thickness, demonstrated a high specific capacitance of 278 F g-1,excellent rate capability (81.2 %), and good cycle stability (91.3 % capacitance retention after 10,000 cycles) as electrode material for SC.