(491g) Sulfur Self-Doped Micro/Mesoporous Carbon Derived from Lignin and Its Application on Supercapacitor  and Oxygen Reduction Reaction

The growing global concerns about energy needs, fossil fuels consumption and the related environmental issues have motived scientists to find new, green and sustainable energy resources and technologies. In this work, byproduct lignin was successfully converted into self-sulfur-doped graphitic carbons via in situ hydrothermal carbonization (HTC) by following the post-annealing treatment at elevated temperature. The surface, porosity, textural, structural and morphological properties of synthesized materials were investigated by SEM, XPS, Raman, FTIR and surface area analyzer. Electrochemical properties of the prepared materials were analyzed by cyclic voltammetry (CV), charge-discharge (CD), electrochemical impedance spectroscopy (EIS), linear sweep voltammetry (LSE) in a KOH electrolyte solution. Up to 3.5 wt. % sulfur intercalating on carbon molecules was successfully achieved. The resulting materials electrode displays high surface area (up to 550 m² g^-1) with mesoporous structure and partially graphitic/amorphous carbon structure. The obtained original electrode materials result in high electrochemical activity for supercapacitor applications. The SGC-850 electrode exhibited a specific capacitance value of 225 g^-1 at a scan rate of 1 A g^-1. The SGC-850 electrode revealed a very consistent response over 10000 cycles at a harsh condition of 5 A g^-1 current density. In addition to supercapacitor application, the obtained material was tested for oxygen reduction reaction (ORR) application. The ORR CV curve of the SGC-850 presents well-defined cathodic peak in the O₂ electrolyte. The SGC-850 goes under 4 electron pathway for the O₂ reduction. To sum up, metal-free SGC-850 is promising candidate electrode materials for supercapacitors and ORR applications.