Efficient proton conduction in porous and crystalline covalent-organic frameworks(COFs)

To attain the objectives of carbon peaking and carbon neutrality,the development of stable and highperformance ion-conducting materials holds enormous relevance in various energy storage and conversion devices.Particularly,crystalline porous materials possessing built-in ordered nanochannels exhibit remarkable superiority in comprehending the ion transfer mechanisms with precision.In this regard,covalent organic frameworks(COFs)are highly regarded as a promising alternative due to their preeminent structural tunability,accessible well-defined pores,and excellent thermal/chemical stability under hydrous/anhydrous conditions.By the availability of organic units and the diversity of topologies and connections,advances in COFs have been increasing rapidly over the last decade and they have emerged as a new field of proton-conducting materials.Therefore,a comprehensive summary and discussion are urgently needed to provide an"at a glance"understanding of the prospects and challenges in the development of proton-conducting COFs.In this review,we target a comprehensive review of COFs in the field of proton conductivity from the aspects of design strategies,the proton conducting mechanism/features,the relationships of structure-function,and the application of research.The relevant content of theoretical simulation,advanced structural characterizations,prospects,and challenges are also presented elaborately and critically.More importantly,we sincerely hope that this progress report will form a consistent view of this field and provide inspiration for future research.

Construction of biomimetic proton transport channels in metal-organic framework

Construction of proton transport channels in metal-organic frameworks(MOFs)with simple synthesis processes,high proton conductivities and good performance stabilities has been of great interest for proton exchange membrane fuel cell(PEMFC).Herein,we mimic the proton transport behavior of amino acid residues in bacteriorhodopsin,select UiO-66-COOH as the host,glycine and aspartic acid as the functional guest molecules,and then functionalize the MOF framework with amino acids to obtain biomimetic proton transport channels.This strategy endows UiO-66-COOH-Asp a high proton conductivity of 1.19×10^(-2)S/cm at 70℃and 98%RH,excellent cycle stability of performances and performance durability,which can be comparable to the reported MOFs-based proton conductors.Moreover,the proton conduction mechanism in UiO-66-COOH-Asp is elaborated in detail due to its visual structure,which is also one of the advantages of adopting MOFs as research platform,making it possible to optimize the structure-activity relationship of advanced materials.Notably,this strategy has clear objectives and simple synthesis,which has made certain contributions to both theoretical research and future industrial production of proton conductors.