Electronic Effect-Modulated Enhancements of Proton Conductivity in Porous Organic Polymers

We proposed a new strategy to maximize the density of acidic groups by modulating the electronic effects of the substituents for high-performance proton conductors. The conductivity of the sulfonated 1-MeL40-S with methyl group corresponds to 2.29×10^-1  S cm^-1 at 80 °C and 90 % relative humidity, remarkably an 22100-fold enhancement over the nonsulfonated 1-MeL40. 1-MeL40-S maintains long-term conductivity for one month. We confirm that this synthetic method is generalized to the extended version POPs, 2-MeL40-S and 3-MeL40-S. In particular, the conductivities of the POPs compete with those of top-level porous organic conductors. Moreover, the activation energy of the POPs is lower than that of the top-performing materials. This study demonstrates that systematic alteration of the electronic effects of substituents is a useful route to improve the conductivity and long-term durability of proton-conducting materials.

Large-area Free-standing Metalloporphyrin-based Covalent Organic Framework Films by Liquid-air Interfacial Polymerization for Oxygen Electrocatalysis

Synthesizing large-area free-standing covalent organic framework (COF) films is of vital importance for their applications but is still a big challenge. Herein, we reported the synthesis of large metalloporphyrin-based COF films and their applications for oxygen electrocatalysis. The reaction of meso-benzohydrazide-substituted metal porphyrins with tris-aldehyde linkers afforded free-standing COF films at the liquid-air interface. These films can be scaled up to 3000 cm² area and display great mechanical stability and structural integrity. Importantly, the Co-porphyrin-based films are efficient for electrocatalytic O₂ reduction and evolution reactions. A flexible, all-solid-state Zn-air battery was assembled using the films and showed high performance with a charge-discharge voltage gap of 0.88 V at 1 mA cm^-2 and high stability under bent conditions (0° to 180°). This work thus presents a strategy to synthesize functionalized COF films with high quality for uses in flexible electronics.

Electrochemical Double-Layer Capacitor based on Carbon@ Covalent Organic Framework Aerogels

High energy demand results in comprehensive research of novel materials for energy sources and storage applications. Covalent organic frameworks (COFs) possess appropriate features such as long-range order, permanent porosity, tunable pore size, and ion diffusion pathways to be competitive electrode materials. Herein, we present a deep electrochemical study of two COF-aerogels shaped into flexible COF-electrodes (ECOFs) by a simple compression method to fabricate an electrochemical double-layer capacitor (EDLC). This energy storage system has considerable interest owing to its high-power density and long cycle life compared with batteries. Our result confirmed the outstanding behavior of ECOFs as EDLC devices with a capacity retention of almost 100 % after 10 000 charge/discharge cycles and, to our knowledge, the highest areal capacitance (9.55 mF cm^-2 ) in aqueous electrolytes at higher scan rates (1000 mV s^-1 ) for COFs. More importantly, the hierarchical porosity observed in the ECOFs increases ion transport, which permits a fast interface polarization (low τ₀ values). The complete sheds light on using ECOFs as novel electrode material to fabricate EDLC devices.