Cattail leaf-derived nitrogen-doped carbons via hydrothermal ammonia treatment for electrocatalytic oxygen reduction in an alkaline electrolyte
Cattail leaf-derived nitrogen-doped carbons via hydrothermal ammonia treatment for electrocatalytic oxygen reduction in an alkaline electrolyte
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DOI：
10.1016/j.ijhydene.2022.05.213
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发表时间：
2022-06
影响因子：
7.2
通讯作者：
G. Panomsuwan;A. Eiad-ua;N. Kaewtrakulchai;Ai Seizawa;T. Ishizaki
中科院分区：
文献类型：
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作者：
G. Panomsuwan;A. Eiad-ua;N. Kaewtrakulchai;Ai Seizawa;T. Ishizaki
采用水热法在氨溶液中制备香蒲叶衍生的氮掺杂碳（CL-NCs）作为氧还原反应（ORR）的催化剂。在1.0、1.5和2.0 M的氨浓度下改变氮掺杂含量。表征结果表明，cl - nc呈非晶结构，结构缺陷密度随氨浓度的增加而增加。未经水热氨处理制备的CL-NC具有低比表面积（5 m2g−1）的无孔结构。经水热氨处理后，CL-NCs具有较高的比表面积（113 ~ 496 m2g−1）的微介孔结构；然而，在较高的氨浓度下，由于孔隙结构的恶化，表面积明显减少。cl - nc中氮掺杂含量在0.65 ~ 1.55原子%之间，以吡啶- n和石墨- n为主。在碱性电解液（0.1 M KOH）中进行电化学评价时，1.0 M氨浓度制备的CL-NC在所有样品中表现出最高的ORR活性，表现为最正的起始电位（- 0.05 V vs. Ag/AgCl）和半波电位（- 0.22 V vs. Ag/AgCl），以及最高的扩散限制电流密度，通过直接四电子途径还原更有利（n= 3.23-3.52）。cl - nc的ORR活性与比表面积而非氮掺杂含量的变化趋势相似，表明比表面积和孔隙度对提高ORR活性有重要作用。在长期运行和甲醇环境下，具有良好的稳定性。本研究结果可为进一步开发和利用生物质NCs作为ORR催化剂提供参考。
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 m2g−1). With hydrothermal ammonia treatment, CL-NCs exhibited a micro–mesoporous structure with a higher surface area (113–496 m2g−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.