Folic Acid Coordinated Cu–Co Site N-Doped Carbon Nanosheets for Oxygen Reduction Reaction

Abstract

The design and development of carbon materials with high-efficiency oxygen reduction activity is still a problem. Folic acid (FA) has unique structural characteristics, and it can provide multiple coordination sites for metal ions. Here, folic acid (FA) was used as a metal complex ligand, and Cu–Co-based N-doped porous carbon nanosheets (Cu–CoNCNs) were synthesized by the solvothermal method, the molten salt template-assisted calcination method, and the chemical etching method. The Cu–CoNCNs synthesized by this method have highly efficient oxygen reduction reaction (ORR) activity. In 0.1 mol/L KOH electrolytes, the catalyst exhibits excellent ORR activity and has a fairly high half-wave potential (0.905 V vs reversible hydrogen electrode (RHE)). X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, infrared spectroscopy, and X-ray diffraction (XRD) were used to investigate the reasons why the catalyst has excellent catalytic activity and long-life stability. It was proved that the impressive ORR activity of Cu–CoNCNs comes from Cu doping, which can regulate the surface electronic structure of the catalyst, thereby optimizing the binding ability between the intermediate and adsorbed species and improving the catalytic activity.

Bimetallic CuCo@Nitrogen/Carbon Nanoparticles as a Cathode Catalyst for Magnesium‐Air Batteries

“…The half‐wave potential of CuCo@N/C‐800 only has a merely 8 mV negative shift between the initial and after 5000 cycles, suggesting the superior durability and stability. These electrochemical results illustrate that the CuCo@N/C‐800 possesses outstanding ORR performances, first‐order reaction kinetic, 4 e − pathway and remarkable durability and stability, which may be Cu doping adjust the electronic structure of Co@NC‐800 and improve the activities of ORR [36] …”

“…As revealed in Figure S2, the CV curves of CuCo@N/C‐800 and Co@N/C‐800 are not observed obvious reduction peak in the N 2 ‐saturated electrolyte. But the CV curves of as‐obtained electrocatalysts and commercial Pt/C exhibit a significant oxygen reduction peak under O 2 ‐saturated electrolyte in Figure 5a, demonstrating the series of CuCo@N/C catalysts and Co@N/C‐800 have obvious electrocatalytic activity for ORR [36] . Among these as‐prepared electrocatalysts, the CuCo@N/C‐800 possesses more positive oxygen reduction peak approximately at 0.79 V and more closer to Pt/C (0.84 V) than that of Co@N/C‐800 (0.76 V), CuCo@N/C‐600 (0.77 V) and CuCo@N/C‐1000 (0.67 V), indicating the superior ORR activity.…”

Ternary Nanohybrids Comprising N-Doped Graphene and WSe2–WO3 Nanosheets Enable High-Mass-Loading Electrodes with Long-Term Stability for Hydrogen Evolution

“…Four different peaks were observed at 398.8, 400.4, 401.6, and 403.0 eV, and are attributed to pyridinic N, pyrrolic N, graphitic N, and oxidized N, respectively. 60 Interestingly, the content of graphitic N in the NG/W−Ws (28.9%) is higher than that in the NC/W−Ws (20.9%), without any peak shifts (or without emergence of additional peaks). This indicates that intercalated PANI in the former rendered N atoms to graphene sheets during the carbonization process.…”

“…The N-doping contents of the NG/W–Ws and NC/W–Ws were examined using the N 1s data, as exhibited in Figure c. Four different peaks were observed at 398.8, 400.4, 401.6, and 403.0 eV, and are attributed to pyridinic N, pyrrolic N, graphitic N, and oxidized N, respectively . Interestingly, the content of graphitic N in the NG/W–Ws (28.9%) is higher than that in the NC/W–Ws (20.9%), without any peak shifts (or without emergence of additional peaks).…”

Encapsulation of Ultrafine Metal–Organic Framework Nanoparticles within Multichamber Carbon Spheres by a Two-Step Double-Solvent Strategy for High-Performance Catalysts

“…As shown in Figure a, the peaks of the N 1s spectra of MCCS-400, MCCS-400-Co, and ZIF-67@MCCS-400 were superimposed, and the peak of MCCS-400-Co shifted to the low-energy band region, indicating that there is an interaction force between Co and N. Moreover, when Co 2+ ions were used as metal sources to generate ZIF-67, the shift disappeared, indicating that this force disappeared. On the other hand, we further analyzed the Co 2p spectra of MCCS-400-Co, ZIF-67@MCCS-400, and ZIF-67 (Figure b); the Co 2p peaks at 781.1 and 782.7 eV in ZIF-67 represent Co-N x ( x < 4) and Co-N 4 coordination environments, − respectively, and the other two peaks were considered as satellite peaks. Compared to ZIF-67, the peaks for ZIF-67@MCCS-400 and MCCS-400-Co shifted to a lower binding energy, corresponding to Co-N x , suggesting a strong chemical bond forming between Co and pyridinic and/or pyrrolic-N with a high electronegativity, leading to partial electron migration from Co to pyridinic and/or pyrrolic-N.…”