Covalent Pyrimidine Frameworks via a Tandem Polycondensation Method for Photocatalytic Hydrogen Production and Proton Conduction

Abstract

The development of heteroaromatic conjugated porous polymers (H‐CPPs) have received enormous research interests, because of the important functional roles of the heteroatoms in photocatalysis and proton conduction. However, due to the synthetic challenges deriving from the stable structures, the structural diversity and synthetic methods of them are still limited. Herein, a new type of H‐CPPs, covalent pyrimidine frameworks (CPFs), via an efficient tandem polycondensation reaction between aldehyde, acetyl, and amidine monomers is reported. The resulting CPFs are bridged by pyrimidine units, rich of nitrogen atoms and can be structurally regulated on demand. The CPFs are shown to be active photocatalysts for hydrogen evolution from methanol via a photo‐thermo‐catalysis process, achieving an excellent hydrogen evolution rate of 5282.8 µmol h−1 g−1. The CPFs can be further processed into a mixed matrix membrane, displaying an excellent proton conductivity of 1.30 × 10−2 S cm−1 at 413 K under anhydrous condition.

Construction of dense H-bond acceptors in the channels of covalent organic frameworks for proton conduction

“…15 Therefore, it is essential to design electrolyte materials with anhydrous proton conduction at temperatures above 100 °C. 16 Furthermore, exploration of the conductive mechanism and the relationship between structure and conduction is also important. 17,18 Covalent organic frameworks (COFs) are a type of crystalline and ordered porous polymers that are constructed by organic structural units via covalent bonds.…”

“…15 Therefore, it is essential to design electrolyte materials with anhydrous proton conduction at temperatures above 100 °C. 16 Furthermore, exploration of the conductive mechanism and the relationship between structure and conduction is also important. 17,18…”

Bioinspired Heterogeneous Construction of Lignocellulose‐Reinforced COF Membranes for Efficient Proton Conduction

“…[5][6][7][8] During the past decades, crystalline porous materials (CPMs) with ordered and built-in nanochannels have been widely developed as proton conductors due to their tremendous advantages in accurately understanding the proton transfer mechanism. [9][10][11][12] For example, metal-organic frameworks (MOFs) can induce fast proton conduction by integrating functional acidic groups (e.g., HCl, H 3 PO 4 , H 2 SO 4 , and CF 3 SO 3 H) onto the channel walls or hosting guest molecules (such as imidazole and water) in welldefined pores. [13][14][15] Hydrogen-bonded organic frameworks (HOFs) can facilitate efficient proton conduction by hosting protonic guest solvent molecules (H 2 O, NH 3 ) in the channels.…”

Comparative Study on Proton Conductivity and Mechanism Analysis of Two Imidazole Modified Imine‐Based Covalent Organic Frameworks

“…Accordingly, some researchers fabricated functionalized COFs by attaching functional groups (such as sulfonic acid groups [36,37] as well as azo groups [34] ) as proton donors or acceptors on the monomer to achieve stable and high proton conductivity, but such COFs with functionalized side chain groups are usually more difficult to achieve. In addition to this strategy to enhance the intrinsic σ, the proton conductivity of COFs can also be boosted by loading acidic molecules (p-toluenesulfonic acid PTSA, [38] H 3 PO 4 , [39][40][41] phytate, [42] etc.) or N-heterocycles (triazole, [43] tetrazole, [44] imidazole(Im) [45] ), as extrinsic proton sources.…”