Domain‐Confined Etching Strategy to Regulate Defective Sites in Carbon for High‐Efficiency Electrocatalytic Oxygen Reduction

Abstract

Coupling sites of nitrogen dopants and intrinsic carbon defects (N/DC) in metal‐free carbon are highly active toward electrocatalytic oxygen reduction reaction (ORR), and yet they are hard to be effectively constructed. Here, a novel synthesis strategy for fabrication of N/DC‐enriched metal‐free carbon from precursors containing metal‐nitrogen moieties (M‐Nx) is reported. During pyrolysis of the precursors, the M‐Nx is in situ converted to endogenous metal oxides (MOx) via a halide‐mediated “bait and switch” mechanism to realize a domain‐confined etching of the carbon matrix around the nitrogen dopants, forming abundant N/DC coupling sites in the final carbon products. The optimized N/DC‐enriched carbon exhibits an outstanding ORR activity and stability with a half‐wave potential of 0.903 V (versus RHE) in 0.1 m KOH solution, outperforming most of the reported metal‐free carbon catalysts. Experimental investigations and theoretical calculations demonstrate an improved electron‐donating ability and optimized binding energies of the N/DC coupling sites toward the ORR intermediates, which are primarily responsible for such an excellent ORR activity. This domain‐confined endogenous MOx etching strategy is also widely applicable to different M‐Nx‐containing precursors as well as different halide mediators, which opens up new possibilities to fabricate metal/nonmetal doped carbon materials enriched with various coupling sites of desired synergistic properties.

NiFe-CN catalysts derived from the solid-phase exfoliation of NiFe-layered double hydroxide for CO2 electroreduction

“…S6, ESI†) was abundant and continuous, which was beneficial to expose more active sites and for proton transfer. 54,55…”

Singlet Oxygen Induced Site‐Specific Etching Boosts Nitrogen‐Carbon Sites for High‐Efficiency Oxygen Reduction

“…[5] However, few of the reported synthetic strategies were capable of directionally settling the intrinsic carbon defects next to the N dopants to realize such a boosting effect. Our recent work presented the directional construction of sp 3 CÀ PyÀ N active sites in metal-free N-doped carbon, [6] but such a synthesis strategy required that the precursors contained MÀ N x moieties (M represents a metal). Therefore, it would be ideal to develop a more universal synthesis strategy for the controllable and targeted construction of intrinsic carbon defects in the adjacent regions of the N-dopants to further boost the intrinsic catalytic activity of the NÀ C sites toward ORR.…”

Impact of Pore Structure on Electrochemical Reduction of Carbon Dioxide in Iron- and Nitrogen-Doped Carbon Materials: Solid–Liquid Interface Versus Solid–Gas–Liquid Triple-Phase Boundary

“…The interface microenvironment near catalytic sites is a critical factor that determines the reaction activity and selectivity in many heterogeneous electrocatalytic systems. − A typical example is the electrocatalytic reduction of carbon dioxide (CO 2 RR). The CO 2 RR takes place at the boundary where catalytic active site, electrolyte, and gas meet. , The interface microenvironment, such as local concentration equilibrium of different reactants or products, , local pH, , and interface structure, , can greatly affect the catalysis and selectivity of CO 2 RR.…”