Lanthanoid coordination compounds as diverse self-templating agents towards hierarchically porous Fe–N–C electrocatalysts

Abstract

Pore structure is a critical material property of carbon materials, determining their surface area, active sites accessibility, wettability, and efficiency of bubble removal. In the self-templating approach to pore design,...

Hydrazine Oxidation Electrocatalysis

“…Evidence that the HzOR is efficiently catalyzed by atomically dispersed M-NM x /C materials began to be accumulated since 2020, 184,176,185 although such sites have probably contributed to the HzOR on all Fe−N−C materials reported before that. 174,98,97,186 Wang et al was the first to prepare and assign a pyrrole-type FeN 4 on carbon fiber, exhibiting an early E onset = 0.25 vs RHE for the HzOR at pH 14 (Figure 5a).…”

“…(a) A Fe–N 4 /C HzOR electrocatalyst; inset: a proposed structure of a N 2 H 4 -binding Fe–N 4 /C site . (b) Hierarchically porous Fe–N–Cs, showing effect of pore structure on bubble removal . (c) PGM SACs on Co 2 P; inset: HAADF-STEM of Pt atoms in the Co 2 P lattice .…”

“…Complex structures such as vertical graphene stacks on SiO 2 /Si can enhance HzOR currents by exposing edge sites and releasing N 2 bubbles faster than smooth carbon . Bubble removal was recently studied in a family of Fe–N x /C materials with varying pore structures (Figure b), prepared by the self-templating method. − The frequency and magnitude of current jumps, associated with bubble release, varied along the series, demonstrating a preference for hierarchically porous carbon, rich in pores of 1–100 nm diameters. This phenomenon again points to the importance of an aerophobic surface for improved HzOR activity.…”

Carbon Nitrides from Supramolecular Crystals: From Single Atoms to Heterojunctions and Advanced Photoelectrodes

“…Upon pyrolysis at high temperatures (800–1000 °C), M−N x active sites embedded in a highly porous conductive carbon framework are obtained [32] that are able to catalyze reactions such as the electrochemical oxygen reduction or CO 2 reduction [33–36] . Beyond MOFs, crystalline coordination polymers have been employed as templates for highly porous carbon materials; [37–39] very recently, Eisenberg and co‐workers employed magnesium and various lanthanide iminodiacetates as self‐templating agents to prepare carbon‐based electrocatalysts on a large scale with preserved M−N x active sites as well as micro and mesoporosity [40,41] …”

“…[33][34][35][36] Beyond MOFs, crystalline coordination polymers have been employed as templates for highly porous carbon materials; [37][38][39] very recently, Eisenberg and co-workers employed magnesium and various lanthanide iminodiacetates as self-templating agents to prepare carbon-based electrocatalysts on a large scale with preserved MÀ N x active sites as well as micro and mesoporosity. [40,41] Unlike for carbon materials, the advantages of utilizing highly crystalline precursors (C/N-based molecular single crystals) in the synthesis of semiconducting CNs have not been fully exploited so far. A single crystal is a solid with an ordered three-dimensional arrangement of atoms that is repeated through the entire volume, implying no boundaries or defects.…”