Facile and Gram-scale Synthesis of Metal-free Catalysts: Toward Realistic Applications for Fuel Cells

Abstract

Although numerous reports on nonprecious metal catalysts for replacing expensive Pt-based catalysts have been published, few of these studies have demonstrated their practical application in fuel cells. In this work, we report graphitic carbon nitride and carbon nanofiber hybrid materials synthesized by a facile and gram-scale method via liquid-based reactions, without the use of toxic materials or a high pressure-high temperature reactor, for use as fuel cell cathodes. The resulting materials exhibited remarkable methanol tolerance, selectivity, and stability even without a metal dopant. Furthermore, these completely metal-free catalysts exhibited outstanding performance as cathode materials in an actual fuel cell device: a membrane electrode assembly with both acidic and alkaline polymer electrolytes. The fabrication method and remarkable performance of the single cell produced in this study represent progressive steps toward the realistic application of metal-free cathode electrocatalysts in fuel cells.

3D graphene preparation via covalent amide functionalization for efficient metal-free electrocatalysis in oxygen reduction

“…Thus, sp 3 -DABu or sp 2 -DABe acted as the junction that caused the partial electron transfer from electron-rich rGO sheets. However, it is reported that the pyridinic-like N play a critical role in determining the ORR activity among all kinds of N configurations in N-containing rGO 15 45 . The highest content of pyridinic-like N was found in the rGO-sp 3 -rGO (42.7%) compared to rGO-sp 2 -rGO (33.9%) ( Figure S2b ).…”

“…Figure 2c shows the N1s XPS spectra of rGO-sp 2 -rGO, rGO-sp 3 -rGO, and pure sp 3 -DABu with two absorbance peaks. In pure sp 3 -DABu, absorbance peaks at 401.05 and 398.4 eV were attributed to the amine (–NH 2 ) and pyridinic-like N (C–N–C) bonds, respectively 44 45 46 47 . In the rGO-sp 2 -rGO (N content 7.85 wt%) and rGO-sp 3 -rGO (N content 7.87 wt%) samples, the peaks were located at 401.05 and 399.2 eV, respectively.…”

Coffee Waste-Derived Hierarchical Porous Carbon as a Highly Active and Durable Electrocatalyst for Electrochemical Energy Applications

“…In accordance with the active sites issues, which factors can affect the four-electron pathway is still under debate. Graphitic nitrogen has been suggested by the four-electron pathway active site; 57,58 however, pyridinic nitrogen also has been suggested as an efficient active site. 59,60 In our samples, we cannot find trend to support the selectivity increase of CCW_AT over CCW_T in terms of active-site issues, such as nitrogen-doping level, functionalities, and carbon character among all CCW_T and CCW_AT.…”

Flexible semi-amorphous carbon nitride films with outstanding electrochemical stability derived from soluble polymeric precursors

“…It is of critical importance to maintain the temperature below 0 °C during all the process of cyanuric chloride addition. At higher temperatures, an insoluble product is formed, probably as a result of cross-linking due to known noticeable reactivity of the last chlorine atom in cyanuric chloride at elevated temperatures [11]. Solvent exclusion chromatography (SEC, GPC) of the polymers was carried out for as-synthesized solutions, diluted by DMF with LiBr.…”

“…For instance, in the work by Ok-Hee Kim et al [11], carbon nitride material has been synthesized by the condensation of melamine and cyanuric chloride in N,N-dimethylformamide; Xu et al [5] used as precursor a supramolecular complex of cyanuric chloride with 2,4-diamino-6-phenyl-1,3,5-tiazine (benzoguanamine). However, to the best of our knowledge no solution-based approaches allowing obtaining mechanically robust carbon nitride coatings have been proposed to date.…”