Individual High-Quality N-Doped Carbon Nanotubes Embedded with Nonprecious Metal Nanoparticles toward Electrochemical Reaction

Abstract

Developing highly active and stable nonprecious metal catalysts for electrochemical reactions is desirable but remains a great challenge. Herein, we report a novel metal-ion adsorption-pyrolysis strategy for the controllable zeolitic imidazolate framework-8 derived synthesis of individual high-quality N-doped carbon nanotubes embedded with well-dispersed nonprecious metal nanoparticles, which exhibit superior electrocatalytic activity and stability for electrochemical CO2 reduction reaction, oxygen reduction reaction, and oxygen evolution reaction. Experimental analysis and density functional theory calculations indicate that the remarkable electrocatalytic activities are mainly attributed to the interface effects for the efficient electron transfer from metal nanoparticles to the N-doped carbon shell, as well as the large specific areas, unique tube structures, appropriate doping, high graphitization degree, and robust frameworks. The high reaction stability is attributed to the multiwalled graphitic carbon shells efficiently preventing metal nanoparticles from aggregation, corrosion, and oxidation. This novel synthetic strategy presents a facile universality for synthesizing N-doped carbon nanotube structures and will provide a guideline for developing low-cost, highly active, and stable electrocatalytic materials for sustainable energy conversion.

Nonprecious Catalyst for Three-Phase Contact in a Proton Exchange Membrane CO2 Conversion Full Cell for Efficient Electrochemical Reduction of Carbon Dioxide

“…It is noteworthy that the upshift of the DOS of Fe 3 C–NC near the Fermi level is a strong indication of the superior charge transfer between Fe 3 C NPs and the carbon framework. The above results indicate that Fe 3 C NPs confined inside the NCNTs can provide electron transfer to activate the outer layer of the NCNTs , which can promote the catalytic activity of Fe 3 C@NCNTs toward the CO 2 RR Figure b depicts the DOS of CO 2 and Fe 3 C–NC in isolated as well as in combined systems (CO 2 –Fe 3 C–NC).…”

“…The stability of the Fe 3 C@NCNTs electrode was investigated for an electrolysis time of 16 000 s at −0.68 V vs NHE. The current density showed negligible change with the reaction time, indicating the high stability of the catalyst in the electrolyte (Figure f) that might be attributed to the multiwalled graphitic carbon layers formed inside the NCNTs, which can prevent the metal nanoparticles from aggregation, corrosion, or oxidation for a prolonged duration of time. , …”

“…The current density showed negligible change with the reaction time, indicating the high stability of the catalyst in the electrolyte (Figure 3f) that might be attributed to the multiwalled graphitic carbon layers formed inside the NCNTs, which can prevent the metal nanoparticles from aggregation, corrosion, or oxidation for a prolonged duration of time. 43,44 But it has to be mentioned that the mass transfer procedure will be varying in the case of full-cell measurements when compared to the half-cell reactions. This is mainly because of the fact that in a half-cell measurement, electrons, protons, and CO 2 gas molecules are readily available for the reactions to occur, whereas in the case of a full-cell measurement, electrons and protons are being produced by splitting the water at the anode and the reaction with CO 2 occurs after the proton gets transmitted to the cathode and recombines with the electron.…”

Simultaneously Realizing Rapid Electron Transfer and Mass Transport in Jellyfish‐Like Mott–Schottky Nanoreactors for Oxygen Reduction Reaction

“…200 mg precursor and a certain amount of dicyandiamide were transferred to a porcelain boat, and annealing at 800 °C for 2 h under a H 2 /Ar atmosphere (10% H 2 ) 37,38. According to different mass ratios of dicyandiamide and Fe(NO 3 ) 3 ‐PVP precursor, the obtained powders were named as HPCM‐2, HPCM‐5, and HPCM‐10, respectively.…”

Polymer-Derived Heteroatom-Doped Porous Carbon Materials

“…Heteroatom-doped carbon micro/nanotubes used as electrode materials for batteries have shown significant advantages compared to fiber materials due to their enhanced surface-to-volume ratio for the electrode–electrolyte interface. , Moreover, these 1D hollow carbon tubes can be easily functionalized with various secondary structural components to meet the requirements of energy conversion and storage devices for real-life applications. For instance, Lee et al successfully fabricated N-doped hollow CNFs by carbonization of polymer fibers.…”