Cattail leaf-derived nitrogen-doped carbons via hydrothermal ammonia treatment for electrocatalytic oxygen reduction in an alkaline electrolyte. (12th July 2022)

• Record Type: Journal Article
• Authors: Panomsuwan, Gasidit; Eiad-ua, Apiluck; Kaewtrakulchai, Napat; Seizawa, Ai; Ishizaki, Takahiro
• Is Part Of: International journal of hydrogen energy. Volume 47:Number 59(2022)
• Page Start: 24738
• Page End: 24749
• Publication Date: 2022-07-12
• Subjects: Nitrogen-doped carbons -- Cattail leaves -- Biomass -- Electrocatalysts -- Hydrothermal ammonia treatment -- Oxygen reduction reaction; Hydrogen as fuel -- Periodicals; Hydrogène (Combustible) -- Périodiques; Hydrogen as fuel; Periodicals; 665.81
• DOI: 10.1016/j.ijhydene.2022.05.213
• Languages: English
• ISSNs: 0360-3199

Abstract

Abstract: Cattail leaf-derived nitrogen-doped carbons (CL-NCs) were prepared by hydrothermal treatment in ammonia solution and subsequent pyrolysis for application as catalysts for the oxygen reduction reaction (ORR). The ammonia concentration was varied at 1.0, 1.5, and 2.0 M to alter the nitrogen doping content. The characterization results revealed that CL-NCs exhibited an amorphous structure, while the density of structural defects increased as the ammonia concentration increased. The CL-NC prepared without hydrothermal ammonia treatment had a nonporous structure with a low specific surface area (5 m 2 g −1 ). With hydrothermal ammonia treatment, CL-NCs exhibited a micro–mesoporous structure with a higher surface area (113–496 m 2 g −1 ); however, the surface area was significantly diminished at higher ammonia concentrations due to the deterioration of the pore structure. The nitrogen-doping content in CL-NCs varied from 0.65 to 1.55 atom% with the predominant ratios of pyridinic-N and graphitic-N. For electrochemical evaluation in an alkaline electrolyte (0.1 M KOH), CL-NC prepared at an ammonia concentration of 1.0 M showed the highest ORR activity among all samples, as indicated by the most positive onset potential (−0.05 V vs. Ag/AgCl) and half-wave potential (−0.22 V vs. Ag/AgCl) as well as the highest diffusion-limiting current density with a more favorable reduction via a direct four-electron pathway ( n = 3.23–3.52). The ORR activity of CL-NCs had a similar trend to their specific surface area rather than nitrogen doping content, indicating the important role of surface area and porosity in enhancing the ORR activity. Moreover, it possessed excellent stability under long-term operation and exposure to methanol. The results obtained in this work could be helpful information for the further development and utilization of biomass-derived NCs for ORR catalysts. Graphical abstract: Image 1 Highlights: CL-NCs were synthesized via hydrothermal ammonia treatment and pyrolysis processes. CL-NCs possessed a high surface area with a micro–mesoporous structure. Nitrogen doping content in CL-NCs increased with increasing ammonia concentration. CL-NCs exhibited good and durable ORR activity in an alkaline electrolyte. Surface area and porosity play important roles in enhancing ORR activity of CL-NCs.