Functional COFs for Electrochemical Sensing: From Design Principles to Analytical Applications

Abstract

At present, applications of covalent organic frameworks (COFs), a class of novel crystalline porous materials fabricated by organic structural blocks only containing light elements such as C, H, N, O and B through strong covalent bonds, in electrochemical sensing have entered a period of rapid development and showed great potential in various analytical fields such as environmental analysis, food analysis, pharmaceutical analysis, biological and clinical analysis owing to their unique advantages including regular porosity, large specific surface area, periodical ordered structure, extended π‐conjugated system, abundant functional groups and outstanding thermal and chemical stability. But there are still many concerns that need to be urgently solved for further electrochemical sensing application including improvement of electric conductivity and enhancement of selectivity. Limited by poor conductivity and low recognition ability of primitive COFs, they always need to be further functionalized. To further promote the development of COFs‐based electrochemical sensing technology, here, we summarize and review the recent advances on construction of two‐dimensional functional COFs materials for electrochemical sensing applications and related sensing device setups in detail, including design strategies, preparation methods, modification considerations, sensing principles and analytical applications, and tentatively propose development prospects and outlooks in future.

Electrochemical Behavior of Niobium Oxide and Titanium Oxide in NaF–Na3AlF6 Molten Salt

“…By combining data for the changes in oxidation-reduction peak current density and potential with respect to the scan rate, it is deduced that the first step in the reduction of Nb 5+ is an irreversible process. For an irreversible electrochemical reaction process, the difference in values between the peak potential and the half-peak potential, which is expressed as E p -E p/2 , should satisfy Equation (1) [23]. According to Equation (1), the charge transfer coefficient (α) of the reduction of Nb 5+ at the Mo cathode is calculated to be approximately 0.97.…”

Expanding the horizons of covalent organic frameworks: sub-stoichiometric synthesis as an emerging toolkit for functional COFs

“…49–52 The field has also witnessed the utilization of unreacted sites, the introduction of non-interfering functional groups, and post-synthetic modifications that functionalize the pores or transform the linkages. 30,33,53 The functional versatility of such framework materials has led to various applications, including gas adsorption/separation, 54–57 host–guest chemistry, 58–61 sensing, 62–68 ion capture/transport, 69 catalysis, 70–76 and electrochemical applications. 77…”