Fluorine-Doped M-N-C Catalysts for Efficient Oxygen Reduction Reaction

Abstract

In recent years, transition metal-nitrogen-carbon (M-N-C) composites are expected to be an alternative to platinum group metal (PGM) among various nonprecious metal catalysts investigated. However, the major challenge comes from insufficient electrocatalytic performance and durability for oxygen reduction reaction (ORR). In addition to the selection of suitable central metal active sites, the electrocatalytic activity and stability of the M-N-C catalysts can be enhanced by adjusting the electronic structure of the catalysts. In this work, M-N-C/F composites were synthesized by loading transition metal phthalocyanine complexes onto pre-fluorinated carbon nanotubes through a simple pyrolysis method. Pyrroline-N(PN) and graphite-N(GN) formed after thermal treatment can act as electron acceptors to modulate their charge distribution on the M-N4 sites, and the use of pre-fluorinated nanotubes also allows for a more controlled introduction of fluoride ions that are well coordinated to transition metals, both of which can modulate and modify the electronic structure of M-N-C catalysts. The obtained manganese phthalocyanine/fluorinated carbon nanotubes at 800°C (MnPc/FCNT800) exhibits a competitive electrocatalytic ORR performance with the half-wave potential (E1/2) of 0.9 V and only 12.1% decay after 20 h long-term chronoamperometry (CA) test in 1.0 M KOH electrolyte, outperforming the commercial Pt/C. Overall, this work paves the way of the electronic structure modification and design of such M-N-C composites for sustainable energy applications.

Mechanically Strong Superabsorbent Terpolymer Hydrogels Based on AMPS via Hydrogen-Bonding Interactions

“…We should note that such a transparent-to-opaque transition with increasing water content was recently reported for PMAAc hydrogels prepared in the presence of TEMED capable of forming H-bond complexes. 23 Our recent molecular dynamic simulation results also predict aggregated configuration of the network chains in MAAc/ DMAA hydrogels due to the formation of strong interchain Hbonds excluding water from the copolymer. 15 To determine the composition of the terpolymer chains in both gel and sol phases, FTIR and elemental microanalysis measurements were conducted on dried hydrogel specimens taken from both phases.…”

Recent Advances in Electrochemical CO2‐to‐Multicarbon Conversion: From Fundamentals to Industrialization

“…[118] Besides, the development of the above-mentioned extrinsic strategies possesses the advantage of scalability and versatility toward the industrial implementation. [357] Therefore, it is necessary to take every link in the electrolytic systems into careful consideration for the optimization of gas-liquid-solid triple-phase boundary, mainly including GDEs, tandem catalysis, multiphysicscoupled eCO 2 conversion, parameters of electrolytic cell, and gas component.…”

Restructuring multi-phase interfaces from Cu-based metal–organic frameworks for selective electroreduction of CO2 to C2H4

“…1,2 Compared with C 1 products (e.g., CO, HCOOH, and CH 4 ), C 2+ ones (e.g., C 2 H 4 and C 2 H 5 OH) feature higher energy density and market value; however, their productivity is seriously limited by the multi-step hydrogenation competing with a series of side-reactions. [3][4][5] So far, Cu is the only metal that can selectively convert CO 2 to C 2+ thanks to the benign bonding of *CO intermediates, 6,7 and its interfaces with tailored valence states, grain boundaries and unsaturated sites are evidenced to surmount the energy barriers of such multiple electron transfer steps. [8][9][10] Although progress has been made in C 2+ production, it's still challenging to facilely construct active interfaces and effectively stabilize them during electrolysis.…”