Flocculant-Assisted Synthesis of Graphene-Like Carbon Nanosheets for Oxygen Reduction Reaction and Supercapacitor

Abstract

The rational treatment of hazardous textile sludge is critical and challenging for the environment and a sustainable future. Here, a water-soluble chitosan derivative was synthesized and used as an effective flocculant in removal of reactive dye from aqueous solution. Employing these chitosan-containing textile sludges as precursors, graphene-like carbon nanosheets were synthesized through simple one-step carbonization with the use of Fe (III) salt as graphitization catalyst. It was found that the resultant graphene-like carbon nanosheets material at thickness near 3.2 nm (NSC-Fe-2) showed a high graphitization degree, high specific surface area, and excellent bifunctional electrochemical performance. As-prepared NSC-Fe-2 catalyst exhibited excellent oxygen reduction reaction (ORR) activity (onset potential 1.05 V) and a much better methanol tolerance than that of commercial Pt/C (onset potential 0.98 V) in an alkaline medium. Additionally, as electrode materials for supercapacitors, NSC-Fe-2 also displayed an outstanding specific capacitance of 195 F g−1 at 1 A g−1 and superior cycling stability (loss of 3.4% after 2500 cycles). The good electrochemical properties of the as-prepared NSC-Fe materials could be attributed to the ultrathin graphene-like nanosheets structure and synergistic effects from codoping of iron and nitrogen. This work develops a simple but effective strategy for direct conversion of textile sewage sludge to value-added graphene-like carbon, which is considered as a promising alternative to fulfill the requirements of environment and energy.

Recent Achievements in Polymer Bio-Based Flocculants for Water Treatment

“…Continuing their research, this team used chitosan-containing textile sludge as precursor of graphene-like carbon nano-sheets designed as electrode material for supercapacitors [ 144 ]. This work focuses on controlling desorption of azo-dye by adjusting pH.…”

Multicomponent doped hierarchically porous carbon derived from natural polyelectrolyte for high‐performance supercapacitors

“…Because its chemical component, chitosan can provide in-situ doping of oxygen and nitrogen, making it an ideal carbon source for the preparation of porous carbon materials. [28][29][30][31][32] However, there aren't many 3D frameworks in porous carbons fabricated from chitosan, 3 which restricts its structure stability in pyrolysis process. How to improve the shortcoming is a challenge for the large-scale applications to be the electrode materials.…”

“…Chitosan, a partial deacetylated derivative of chitin, not only has high reaction activity, but also contains rich hydroxyl and amino groups on the surface of chitosan. Because its chemical component, chitosan can provide in‐situ doping of oxygen and nitrogen, making it an ideal carbon source for the preparation of porous carbon materials 28‐32 . However, there aren’t many 3D frameworks in porous carbons fabricated from chitosan, 3 which restricts its structure stability in pyrolysis process.…”

B/N-Codoped Carbon Nanosheets Derived from the Self-Assembly of Chitosan–Amino Acid Gels for Greatly Improved Supercapacitor Performances

“…The preparation of carbon materials based on CS could converge two general approches: direct carbonization activation − or hydrothermal pretreatment before high-temperature carbonization ,, and gelation pretreatment before high-temperature pyrolysis. − Similar to other polysaccharides, CS contains plenty of amino groups that contribute to adjusting the charged state and have solubility by protonation. More importantly, CS tends to self-gelation in acidic solution.…”