There is an urgent need for developing nonprecious metal catalysts to replace Pt-based electrocatalysts for oxygen reduction reaction (ORR) in fuel cells. Atomically dispersed M−N x /C catalysts have shown promising ORR activity; however, enhancing their performance through modulating their active site structure is still a challenge. In this study, a simple approach was proposed for preparing atomically dispersed iron catalysts embedded in nitrogen-and fluorine-doped porous carbon materials with fivecoordinated Fe−N 5 sites. The C@PVI-(DFTPP)Fe-800 catalyst, obtained through pyrolysis of a bio-inspired iron porphyrin precursor coordinated with an axial imidazole from the surface of polyvinylimidazole-grafted carbon black at 800 °C under an Ar atmosphere, exhibited a high electrocatalytic activity with a half-wave potential of 0.88 V versus the reversible hydrogen electrode for ORR through a four-electron reduction pathway in alkaline media. In addition, an anion-exchange membrane electrode assembly (MEA) with C@PVI-(DFTPP)Fe-800 as the cathode electrocatalyst generated a maximum power density of 0.104 W cm −2 and a current density of 0.317 mA cm −2 . X-ray absorption spectroscopy demonstrated that a single-atom catalyst (Fe−N x /C) with an Fe−N 5 active site can selectively be obtained; furthermore, the catalyst ORR activity can be tuned using fluorine atom doping through appropriate preassembling of the molecular catalyst on a carbon support followed by pyrolysis. This provides an effective strategy to prepare structure-performance-correlated electrocatalysts at the molecular level with a large number of M−N x active sites for ORR. This method can also be utilized for designing other catalysts.
The development of high-performance non-precious metal catalysts for the oxygen reduction reaction (ORR) as an alternative to platinum-based counterparts in fuel cells is highly desirable but challenging. In this study, a facile approach for preparing a porous boron-bearing Fe/N/C catalyst by pyrolysis was reported. The obtained FeCNB-900 with a high surface area (784 m 2 g À 1 ) favored a 4e À -reduction pathway for ORR, with a half-wave potential of~0.86 V vs. RHE and high stability in 0.1 M KOH. Furthermore, anion-exchange membrane fuel cells (AEMFCs) with the use of the FeCNB-900 composite as the cathode catalyst exhibited a maximal power density of 0.172 W cm À 2 without back pressure, revealing its promising potential for application in fuel cells and metal-air batteries. Results demonstrated that the additional doping of B into Fe/N/ C leads to a significant increase in the specific surface area of the catalyst composite and can adjust surface polarities as well as electronic properties and provide more active sites to impart a synergistic effect for boosting catalytic ORR performance.
As an alternative for platinum‐based electrocatalysts, the development of non‐precious metal catalysts for oxygen reduction reaction (ORR) is highly desirable for fuel cell applications. In this paper, we propose a facile preparation method for a B, N‐codoped Cu–N/B–C nanomaterial as an efficient electrocatalyst for ORR in alkaline electrolytes. One‐step heat treatment of cyanamide/melamine, boric acid, and cupric chloride loaded on carbon black produces a Cu–N/B–C composite with a high specific surface area. The Cu–N/B–C‐800 composite pyrolyzed at 800 °C has the best ORR performance among all tested composites. Cu–N/B–C‐800 saw an ORR onset potential at 0.95 V and a half‐wave potential (E1/2) at 0.84 V vs. reversible hydrogen electrode (RHE) in 0.1 M KOH solution, which is comparable to the commercial 20 wt% Pt/C catalyst. Moreover, Cu–N/B–C‐800 has a small negatively shifted E1/2 value (−8.0 mV) under the accelerated‐durability test condition, demonstrating superior stability and higher tolerance to the methanol‐crossover effect compared with the Pt/C catalyst. Furthermore, the anion exchange membrane fuel cell (AEMFC) loaded with Cu–N/B–C‐800 as the cathode catalyst has an open cell voltage of 0.85 V and a peak power density of 80 mW/cm2 at 60 °C without backpressure, which is in the list of optimal non‐precious metal catalysts for ORR in AEMFC.
A unique electrochemical four-component reaction of terminal alkynes, (thio)xanthenes, acetonitrile and water has been established in the absence of any catalyst or external oxidant. This electrochemical reaction features high atom...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.