Well‐Defined Conjugated Reticular Oligomer “Blood Cells” and Conducting Polymer “Neurons” Constructing “Muscle”‐Biomimetic Electrocatalysts for Water Electrolysis

Abstract

Covalent organic frameworks (COFs) provide a tunable platform for water electrolysis. However, it is difficult to perform explicitly structural characterization for COFs due to the uncontrollable polymerization via the solvothermal method, which hinders the clear-cut exploration of the COFs' structureperformance relationship in further applications. Here, the well-defined conjugated reticular oligomers ( CROs) are designed for the first time using an aqueous micellar strategy. The CROs have definite chemical structure and can be regarded as conjugated oligomers or defect-free COFs segment. Using CROs and conducting polymer, three "muscle"-biomimetic electrocatalysts are engineered for splitting water to H 2 and O 2 . The self-assembled "muscle"like structures guarantee fully exposed active sites, fast electron conduction and mass transfer (H 2 O/H 2 /O 2 ). The "muscle"-biomimetic poly(3,4-ethylenedioxythiophene) (PEDOT)/CROs-Ru exhibit superior electrochemical performance than the COFs-Ru. In particular, the mass activity and turnover frequency (TOF) value of PEDOT/CRO OH -8-Ru are ≈95 and 38 times that of the counterpart bulk Py-COF OH . The theoretical calculation and the experimental results demonstrate that the CROs endow the electrocatalyst with an electron-rich surface and enhance carrier mobility. The enhanced water electrolysis activity of CROs-Ru can be attributed to the Schottky heterojunction suppressing the electron backflow, which facilitates the adsorption of hydrogen protons and hydroxides.

Regioisomeric Benzotriazole-Based Covalent Organic Frameworks for High Photocatalytic Activity

“…For symmetry BTz-COF-S, the HOMO and LUMO levels were uniformly delocalized over the entire system, while for symmetry breaking BTz-COF-AS, the HOMO and LUMO levels were totally separated along the frameworks. Especially, the LUMO energy level of BTz-COF-AS merely located partially at the triazole moiety, further indicating the longer conjugation length of symmetric BTz-COF-S. As expected, both single hexagonal unit and the minimum repeating unit of BTz-COF-S displayed smaller bandgaps than those of its asymmetry analogues (Table S2), which could be ascribed to the planar molecular configuration and longer conjugation length of the former . The energy levels obtained from simulation are also in good agreement with the CV results.…”

“…Especially, the LUMO energy level of BTz-COF-AS merely located partially at the triazole moiety, further indicating the longer conjugation length of symmetric BTz-COF-S. As expected, both single hexagonal unit and the minimum repeating unit of BTz-COF-S displayed smaller bandgaps than those of its asymmetry analogues (Table S2), which could be ascribed to the planar molecular configuration and longer conjugation length of the former. 37 The energy levels obtained from simulation are also in good agreement with the CV results. As shown in Figure S19, these two COFs displayed almost the same onset reduction potentials (−0.46 V vs Ag/AgCl), while BTz-COF-S showed a smaller oxidation potential, indicating that both COFs possess identical LUMO levels, while BTz-COF-S has a slightly larger bandgap.…”

Nanoporous Metal/Covalent Organic Framework-Based Electrocatalysts for Water Splitting

“…Through the construction of a muscle biometric electrocatalyst, this innovative combination enhanced the HER rate of COFs and resulted in high performance attributes such as high rates of electron conduction and mass transfer toward electrochemical water splitting because of their highly active sites and large surface area as compared to COF-Ru. 144 Similarly, Yang et al prepared a COF doped with fluorine which exhibited unique physical and chemical properties. The fluorine element, belonging to the halogen family and categorized as a nonmetal, imparts distinct features to COFs.…”

“…Additionally, Liu et al synthesized a well-defined conjugated reticular oligomer (CRO) regarded as a metal-free COF segment and a conducting polymer acting as blood cell and neuron, respectively. Through the construction of a muscle biometric electrocatalyst, this innovative combination enhanced the HER rate of COFs and resulted in high performance attributes such as high rates of electron conduction and mass transfer toward electrochemical water splitting because of their highly active sites and large surface area as compared to COF-Ru . Similarly, Yang et al prepared a COF doped with fluorine which exhibited unique physical and chemical properties.…”

Molecular and Heterojunction Device Engineering of Solution‐Processed Conjugated Reticular Oligomers: Enhanced Photoelectrochemical Hydrogen Evolution through High‐Effective Exciton Separation

“…Two stabilized colloidal solutions of CROs below 10 nm were synthesized by co-polycondensation of bis-benzothiazole diamine (Btz) and tris-benzothiazole triamine (Ttz) with triformylphloroglucinol (Tp) in the catanionic micellar system. [35,38] Building blocks containing bis-and tris-benzothiazole moieties are expected to exert a strong influence, owing to their heightened affinity for H* and their semiconducting properties, which enhance charge carrier mobility. [39] The CROs synthesized with a symmetrical combination of C 3 +C 2 and C 3 +C 3 were designated CRO-BtzTp and CRO-TtzTp, respectively.…”