One‐Dimensional Covalent Organic Frameworks for the 2e⁻ Oxygen Reduction Reaction

Abstract

Two-dimensional covalent organic frameworks (2D COFs) are often employed for electrocatalytic systems because of their structural diversity. However, the efficiency of atom utilization is still in need of improvement, because the catalytic centers are located in the basal layers and it is difficult for the electrolytes to access them. Herein, we demonstrate the use of 1D COFs for the 2e À oxygen reduction reaction (ORR). The use of different four-connectivity blocks resulted in the prepared 1D COFs displaying good crystallinity, high surface areas, and excellent chemical stability. The more exposed catalytic sites resulted in the 1D COFs showing large electrochemically active surface areas, 4.8-fold of that of a control 2D COF, and thus enabled catalysis of the ORR with a higher H 2 O 2 selectivity of 85.8 % and activity, with a TOF value of 0.051 s À 1 at 0.2 V, than a 2D COF (72.9 % and 0.032 s À 1 ). This work paves the way for the development of COFs with low dimensions for electrocatalysis.

Versatile Photoelectrocatalysis Strategy Raising Up the Green Production of Hydrogen Peroxide

“…reported 1D COFs based on 4,4′-(2,2-diphenylethene-1,1-diyl) dibenzaldehyde (TPEDH) linkers (named PYTA-TPEDH-COF and TPETA-TPEDH-COF) for electrochemical H 2 O 2 production with good performance. [166] Among them, PYTA-TPEDH-COF showed the best selectivity for H 2 O 2 production (85.8%) and TOF (0.051 s −1 ) at 0.2 V. Li et al reported an ionic covalent organic polymer (BPyTTz-COP:X) (X = Br − , F − , Cl − or I − ), which was formed by the conjugation of viologen with electron withdrawing thiazolo [5,4-d]thiazole (TTz). [167] BPyTTz-COP: F exhibited the highest H 2 O 2 selectivity (98.5%), high current efficiency (97.2%), and good stability (>10 h).…”

A BODIPY‐Based 1D Covalent Organic Framework for Photocatalytic Aerobic Oxidation

“…[24] Up to now, 1D COFs still very rare and only few examples are reported. [25][26][27][28] Boron-dipyrromethene (BODIPY) dyes are one of the most versatile fluorophores with excellent visible-light absorption ability, thermal and photochemical stabilities, high fluorescence quantum yields, and chemical robustness. [29,30] These photophysical and chemical properties of BODIPY attracted tremendous attentions and they can be widely used in photocatalysis, bioimaging, sensing and luminescent devices.…”

“…Due to the extremely high anisotropy and the entropy‐driven random packing of organic chains, the synthesis of 1D COFs are filled with huge challenge [24] . Up to now, 1D COFs still very rare and only few examples are reported [25–28] …”

Catalytic Linkage Engineering of Covalent Organic Frameworks for the Oxygen Reduction Reaction

“…[3] Among other applications, the COFs can catalyze oxygen reduction reaction (ORR), oxygen evolution reaction, hydrogen evolution reaction, H 2 O 2 synthesis and carbon dioxide reduction by incorporating catalytic metal ions into the knots or immobilized along the porous surfaces. [4] The ORR is a key reaction in energy conversion technologies including fuel cells and metal-air batteries. [5] To achieve highly active catalysts towards ORR, 2D materials (metallenes and transition metal nitrides) and carbon supported metal sites have been widely explored.…”