A Solution‐Processable Porphyrin‐Based Hydrogen‐Bonded Organic Framework for Photoelectrochemical Sensing of Carbon Dioxide

Abstract

Detecting CO2 in complex gas mixtures is challenging due to the presence of competitive gases in ambient atmosphere. Photoelectrochemical (PEC) techniques offer a solution, but material selection and specificity remain limiting. Here, we invented a hydrogen‐bonded organic framework material based on a porphyrin tecton decorated with diaminotriazine (DAT) moieties. The DAT moieties on the porphyrin molecules not only facilitate the formation of complementary hydrogen‐bonds between the tectons but also function as recognition sites in the resulting porous HOF materials for the selective CO2 adsorption. In addition, the in‐plane growth of FDU‐HOF‐2 into anisotropic molecular sheets with large areas of up to 23,000 μm2 and controllable thickness between 0.298 and 2.407 µm were realized by a simple solution‐processing method in over 89% yields. The FDU‐HOF‐2 can be directly grown and deposited onto different substrates including silica, carbon, and metal‐oxides by self‐assembly in situ in formic acid. As a proof of concept, a screen‐printing electrode deposited with FDU‐HOF‐2 was fabricate as a label‐free photoelectrochemical (PEC) sensor for CO2 detection. Such a signal‐off PEC sensor exhibits low detection limit for CO2 (2.3 ppm), reusability (at least 30 cycles), and long‐term working stability (at least 30 days).

Self-Healing Hydrogen-Bonded Organic Frameworks for Low-Concentration Ammonia Capture

“…Many HOF building blocks, including pyrene rings and porphyrins, exhibit good photoelectric activity . Our team had previously reported examples of using HOFs for gas photoelectric sensing. , To evaluate the gas sensing potential of FDU-HOF-3, we used ascorbic acid (AA) as an electron donor on the glassy carbon electrode (GCE) to measure its photocurrent response (Figure D). FDU-HOF-3 had a strong absorption ability and could convert visible light into charge carriers, thus exhibiting a good photocurrent (0.39 μA).…”

Luminescent Porous Organic Crystals for Adsorptive Separation of Toluene and Methylcyclohexane

“…Recently, it has been discovered that numerous noncyclic organic small molecules possess the ability to self-assemble and form organic porous crystals through weak intermolecular interactions, including hydrogen bond (H-bond), van der Waals forces, halogen bonding, and π–π interaction. − Notably, hydrogen-bonded organic frameworks (HOFs) driven by H-bond have experienced rapid advancements in their development. − H-bond exhibits remarkable flexibility and high reversibility, thereby endowing HOFs with inherent advantages such as mild synthesis conditions, excellent solution processability, and facile recrystallization-promoted regeneration and healing.…”

A Solid-State Transformation of Hydrogen-Bonded Organic Frameworks for Efficient Acetylene Storage and Gas Separation

“…In the past few decades, several novel porous materials have been developed, including metal–organic frameworks (MOFs) and covalent organic frameworks (COFs). − Hydrogen-bonded organic frameworks (HOFs) are another newly developed class of porous materials, in which ordered hydrogen-bonded units are established through intermolecular hydrogen-bonding as well as several other interactions (e.g., π···π stacking, van der Waals forces, etc. ). − The favorable solution processability and easy regeneration of HOFs have enabled their widespread interest in the field of gas separation. − With rationally designed hydrogen-bonding arm engineering, HOFs can also possess high surface area, high porosity, and expandable pore sizes. − The tectons with π-conjugated aromatic components allow the inherent good proton conductivity and biocompatibility of the assembled HOFs, thus HOFs are also widely used in optoelectronics, − carrier encapsulation, − and sensing. − …”

“…Concerning the rational design of HOFs with desired functionalities, the construction of HOFs with permanent porosity has been accomplished based on π-conjugated carboxylic acid tectons of porphyrins, pyrenes, polycycles, etc. ,,,− The rigid core and well-oriented hydrogen-bonded dimers make such HOFs feature high stability, high specific surface area, and high pore volume. However, the large pore size leads to insufficient confinement of gas molecules, making it difficult to be effective in critical gas separation.…”