Bipyridine Modified Conjugated Carbon Aerogels as a Platform for the Electrocatalysis of Oxygen Reduction Reaction

Abstract

Aerogels offer a great platform for heterogeneous electrocatalysis owing to their high surface area and porosity. Atomically dispersed transition metal ions can be imbedded in these platforms at ultra‐high site density to make them catalytically active for various reactions. Herein, the synthesis of a new class of conjugated microporous organic aerogels that are used as covalent 3D frameworks for the electrocatalysis of oxygen reduction reaction (ORR) is reported. Modified aerogels functionalized with bipyridine ligands enable copper ion complexation in a single‐step synthesis. The aerogels’ structures are fully characterized using a wide array of spectroscopic and microscopic methods, and heat‐treated in order to make them electronically conductive. After heat treatment at 600 °C, the aerogels maintained their macrostructure and became active ORR catalysts in alkaline environment, showing high mass activity and ultra‐high site density.

Structure–Activity Relationship for the Catalytic Hydrogenation of Nitrobenzene by Single Platinum Atoms Supported on Nitrogen-Doped Carbon

“…51,52 The absorption peaks of the pyridine ring's C−H out-of-plane bending vibration and in-plane deformation vibration were detected at 790, 828, and 1012 cm −1 in pyridine-N x C. The skeletal vibration of the pyridine ring was ascribed to the characteristic peaks at 1460 and 1585 cm −1 . 53 The characteristic peak at 1030 cm −1 in ben-C was attributed to the in-plane bending vibration of aromatic C−H. Typical peaks of the skeletal vibration of the benzene ring were also found at around 1400−1600 cm −1 .…”

“…The peak at 1497 cm –1 corresponded to the CC stretching vibration in the benzene ring, and the peak at 1597 cm –1 was attributed to the in-plane bending vibration of N–H. The band at about 3379 cm –1 was formed by the nitrogen protonation-induced N–H tensile vibration. , The absorption peaks of the pyridine ring’s C–H out-of-plane bending vibration and in-plane deformation vibration were detected at 790, 828, and 1012 cm –1 in pyridine -N x C. The skeletal vibration of the pyridine ring was ascribed to the characteristic peaks at 1460 and 1585 cm –1 . The characteristic peak at 1030 cm –1 in ben -C was attributed to the in-plane bending vibration of aromatic C–H.…”

Recent Progress and Viability of PGM-Free Catalysts for Hydrogen Evolution Reaction and Hydrogen Oxidation Reaction

“…Since the HER kinetics with these catalysts is at least a couple of orders of magnitude lower than that of PGMs, several approaches have been proposed to compensate for that. One promising approach is increasing the catalytic site density, by designing and synthesizing three-dimensional frameworks such as metal organic frameworks (MOFs) and covalent organic frameworks (COFs). ,− …”

Charge-Transfer Mechanism in Oxygen Reduction over Co Porphyrins: Single-Site Molecular Electrocatalysts to Macromolecular Frameworks

“…The same trend could be expanded to a Co porphyrin-ethylene COF, which also shows 90% selectivity toward H 2 O formation and better activity compared to the pure carbon-supported Co porphyrin without direct covalent bonds between the macrocyclic units . The uncovered relations between the charge transfer almost certainly extend far beyond the porphyrins and include polycorroles, Co bipyridine-based aerogels, and other polymerized complexes. − We must note that it was Collman et al who first demonstrated the governing role of interfacial electron flux in ORR selectivity catalyzed by model Fe porphyrin catalysts. , However, the latter studies were performed on simpler systems where the purely heterogeneous intermolecular charge migration is either nonexistent or mediated by a homogeneous charge carrier . Finally, the maximum selectivity to the 4e – pathway we were able to achieve is 47%, which most likely stems from our reliance on alkaline electrolytes to prevent premature deactivation of the catalysts. , …”