Chitosan Intercalated Metal Organic Gel as a Green Precursor of Fe Entrenched and Fe Distributed N-Doped Mesoporous Graphitic Carbon for Oxygen Reduction Reaction

Abstract

Herein, we present Metal‐Organic Gel intercalated with chitosan, a “green” precursor for the synthesis of intrinsic N‐doped Fe entrenched (CHI‐TMA−Fe‐CW) and Fe distributed mesoporous graphitic carbon structures (CHI‐TMA−Fe‐CW−M1) with appreciable Oxygen Reduction Reaction (ORR) activity in alkaline medium. Modulation of the synthetic protocol as a function of reaction kinetics and gelation time while maintaining identical pyrolysis conditions (900 °C, flowing N2 atmosphere) improves the microstructure, surface area and Fe distribution of the graphitic structures (CHI‐TMA−Fe‐CW−M1). CHI‐TMA−Fe‐CW has a Fe entrenched graphitic nanocapsule like morphology while Fe distributed mesoporous graphitic carbon sheets, with a specific surface area value of 565 m2g−1 obtained by modulating the synthesis chemistry in CHI‐TMA−Fe‐CW−M1. The higher percentage of graphitic N in CHI‐TMA−Fe‐CW−M1 apparent from the XPS data validate that the modified synthetic method favours creation of more graphitic N sites contributing for better catalytic performance. CHI‐TMA‐Fe‐CW−M1 catalyst exhibited comparable electrocatalytic activity with that of the commercially available Pt/C via an efficient four‐electron‐dominant ORR pathway with a positive onset potential value of 0.925 V vs RHE. Good durability of CHI‐TMA−Fe‐CW−M1 after 5000 cycles further confirm the prospects of MOG‐chitosan and the feasibility to be used as a potential catalyst for ORR.

Zeolitic Imidazolate Framework-Derived Ordered Pt–Fe Intermetallic Electrocatalysts for High-Performance Zn-Air Batteries

“…What is more, Figure S4 and Table S2 indicated that all the samples contained graphitic N and pyridinic N along with oxidized nitrogen. In addition, the content of pyridinic N and graphitized N is regarded to be beneficial for ORR, which means the change of the content may have an influence on ORR activity . As can be seen from Figure A, when deconvoluted into two couples of peaks including Pt 0 and Pt 2+ , obviously the Pt 4f spectra showed a positive energy shift of ∼0.2 eV upon annealing in 10% H 2 /Ar, which was rooted in the alloying of Pt with transition metals, leading to the improvement of Pt d-band center status. ,, Besides, the high-resolution Fe 2p 3/2 spectra in Figure B showed that the Fe component in the Pt/Fe–NC-900 sample had a higher valence status because of the alloying of Pt with Fe after heat treatment, which was attributed to the lower electronegativity value of Fe (1.83) than that of Pt (2.2) .…”

Hierarchical porous metal–organic gels and derived materials: from fundamentals to potential applications

“…322 To fulfil this requirement, Shijina and colleagues designed a chitosan (CHI) intercalated and Fe complexed-chitosan mediated MIL-101(Fe) MOG. 323 The former was synthesized by first combining Fe 3+ and BTC 3− to obtain a Fe-BTC gel, which was then intercalated with chitosan. The synthesis of the later involved the formation of a complex between Fe and chitosan followed by its conversion to gel by addition of BTC.…”

Metal–Organic Frameworks and Metal–Organic Gels for Oxygen Electrocatalysis: Structural and Compositional Considerations

“…The uniform distribution of individual component as a result of MOG gelation upon pyrolysis led to Fe–Fe 2 O 3 nanoparticles firmly anchored on N‐doped CNTs as an efficient alkaline ORR electrocatalyst. Sailaja and co‐workers [ 204 ] developed Fe–BTC MOG, followed by chitosan solution treatment to prepare chitosan intercalated MOG, which upon inert pyrolysis was formed into Fe entrenched and Fe distributed N‐doped mesoporous graphitic carbon. The resulting material showed enhanced surface area, higher content of N‐dopants and therefore higher ORR catalytic activity compared to the counterpart derived from BTC‐added chitosan–Fe complex.…”