Fe3 C/Fe Decorated N-doped Carbon Derived from Tetrabutylammonium tetrachloroferrate Complex as Bifunctional Electrocatalysts for ORR, OER and Zn-Air Batteries in Alkaline Medium.

The emergence of non-precious metal-based robust and economic bifunctional oxygen electrocatalysts for both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is crucial for the rational design of commercial rechargeable Zn-air batteries (RZAB) with safe energy conversion and storage systems. Herein, a facile strategy to fabricate a cost-efficient, bifunctional oxygen electrocatalyst Fe3 C/Fe decorated N doped carbon (FeC-700, the catalyst prepared at carbinization temperature of 700 °C) with a unique structure has been developed by carbonization of a single source precursor, tetrabutylammonium tetrachloroferrate(III) complex. The ORR and OER activity revealed excellent performance (ΔE=0.77 V) of the FeC-700 electrocatalyst, comparable to commercial Pt/C and RuO2, respectively. The designed temperature-tuneable structure provided sufficiently accessible active sites for the continuous passage of electrons by shortening the mass transfer pathway, leading to extremely durable electrocatalysts with high ECSA and amazing charge transfer performance. Remarkably, the assembled Zn-air batteries with the FeC-700 catalyst as the bifunctional air electrode delivers gratifying charging-discharging ability with an impressive power density of 134 mW cm-2 with a long lifespan, demonstrating prodigious possibilities for practical application.

Ni(II)-Incorporated Ethylene Glycol-Linked Tetraphenyl Porphyrin-Based Covalent Organic Polymer as a Catalyst for Methanol Electrooxidation.

Methanol oxidation reaction (MOR) is a perfect alternative to the conventional oxygen evolution reaction (OER), generally utilized as the anode reaction for hydrogen generation via the electrochemical water splitting method. Moreover, MOR is also relevant to direct methanol fuel cells (DMFCs). These facts motivate the researchers to develop economical and efficient electrocatalysts for MOR. Herein, we have introduced an ethylene glycol-linked tetraphenyl porphyrin-based (EG-POR) covalent organic polymer (COP). The Ni(II)-incorporated EG-POR material Ni-EG-POR displayed excellent OER and MOR activities in an alkaline medium. The materials were thoroughly characterized using 13C solid-state NMR, Fourier transform infrared spectroscopy (FT-IR), Brunauer-Emmett-Teller (BET) surface area analyzer, X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), thermogravimetric analyzer (TGA), and powder X-ray diffraction (PXRD) techniques. These organic-inorganic hybrid materials showed high chemical and thermal stability. Ni-EG-POR requires an overpotential of 400 mV (vs RHE) in OER and 190 mV (vs RHE) in MOR to achieve a current density of 10 mA cm-2. In addition, the catalyst also showed excellent chronoamperometric and chronopotentiometric stability, indicating that the catalyst can provide stable current over a longer period and its potential as a non-noble metal MOR catalyst.