Electron‐Donors–Acceptors Interaction Enhancing Electrocatalytic Activity of Metal‐Organic Polymers for Oxygen Reduction

Abstract

Catalysts with metal‐Nx sites have long been considered as effective electrocatalysts for oxygen reduction reaction (ORR), yet the accurate structure‐property correlations of these active sites remain debatable. Report here is a proof‐of‐concept method to construct 1,4,8,11‐tetraaza[14]annulene (TAA)‐based polymer nanocomposites with well‐managed electronic microenvironment via electron‐donors/acceptors interaction of altering electron‐withdrawing β‐site substituents. DFT calculation proves the optimal −Cl substituted catalyst (CoTAA−Cl@GR) tailored the key OH* intermediate interaction with Co−N4 sites under the d‐orbital regulation, hence reaching the top of ORR performance with excellent turnover frequency (0.49 e s−1 site−1). The combination of in situ scanning electrochemical microscopy and variable‐frequency square wave voltammetry techniques contribute the great ORR kinetics of CoTAA−Cl@GR to the relatively high accessible site density (7.71×1019 site g−1) and fast electron outbound propagation mechanism. This work provides theoretical guidance for rational design of high‐performance catalysts for ORR and beyond.

Engineering organic polymers as emerging sustainable materials for powerful electrocatalysts

“…). 30,34,36,85–88 In this section, we discuss the recent achievements in macromolecular engineering of polymer catalysts from the aspects of intramolecular and intermolecular interactions and mainly focus on their periodic and quasi-periodic architectures. Particular attention is paid to understanding how the architectural and compositional properties polymer catalysts affect their conductivity and pore structure.…”

“…Recently, linear conjugated polymers supported on substrates have been reported to enhance conductivity. 223–225 For example, one of the best-performing metal-free polymers in the realm of ORR catalysts, the covalently linked pyridine and thiophene molecule (P–T) in conjunction with rGO exhibits a half-wave potential of 0.79 V ( vs. RHE) and excellent electrochemical stability. DFT calculations indicate that a molecule containing a phenyl unit (P–Ph) is catalytically inactive.…”

“…Over the past few decades, tremendous progress has been made in developing highly efficient polymer catalysts with various macromolecular architectures, mainly including linear p-conjugated polymers (i.e., linear p-p and p-d conjugated polymers) and nonlinear p-conjugated polymers (i.e., nonlinear p-p conjugated COPs and p-d conjugated MOPs) as well as their hybrids with diverse conductive supports (e.g., graphene, CNTs, etc.). 30,34,36,[85][86][87][88] In this section, we discuss the recent achievements in macromolecular engineering of polymer catalysts from the aspects of intramolecular and intermolecular interactions and mainly focus on their periodic and quasi-periodic architectures. Particular attention is paid to understanding how the architectural and compositional properties polymer catalysts affect their conductivity and pore structure.…”

Precise Design and Modification Engineering of Single‐Atom Catalytic Materials for Oxygen Reduction

“…Based on the in situ electrochemical scanning microscopy (SECM) technique, Tang et al realized the quantitative analysis of the active site density in the actual ORR in the catalyst and visualized the local reaction activity distribution. [113,114] Imaging analysis of the local reactivity of the catalyst was performed at the micron scale using the tip generation/substrate collection (TG/SC) mode (Figure 5c,d). [113] The active site density that actually participated in the electrocatalytic reaction in the catalyst was quantitatively characterized by the surface inquiry electrochemical scanning microscopy (SI-SECM) technique (Figure 5e).…”