Ionothermal Synthesis of Covalent Triazine Frameworks in a NaCl‐KCl‐ZnCl₂Eutectic Salt for the Hydrogen Evolution Reaction

Abstract

Covalent triazine‐based frameworks (CTFs) are typically produced by the salt‐melt polycondensation of aromatic nitriles in the presence of ZnCl2. In this reaction, molten ZnCl2 salt acts as both a solvent and Lewis acid catalyst. However, when cyclotrimerization takes place at temperatures above 300 °C, undesired carbonization occurs. In this study, an ionothermal synthesis method for CTF‐based photocatalysts was developed using a ternary NaCl‐KCl‐ZnCl2 eutectic salt (ES) mixture with a melting point of approximately 200 °C. This temperature is lower than the melting point of pure ZnCl2 (318 °C), thus providing milder salt‐melt conditions. These conditions facilitated the polycondensation process, while avoiding carbonization of the polymeric backbone. The resulting CTF‐ES200 exhibited enhanced optical and electronic properties, and displayed remarkable photocatalytic performance in the hydrogen evolution reaction.

Rational design, application and dynamic evolution of Cu–N–C single-atom catalysts

“…Clean hydrogen energy as sustainable energy can effectively avoid the energy crisis and environmental problems caused by fossil fuels and improve the quality of life of people worldwide. 192,193 Photocatalytic hydrogen evolution is considered to play an important role in the great project of realizing green and sustainable hydrogen energy in the future. 194 In previous reports, Pt-based SACs have attracted extensive attention due to the inherent HER activity of the Pt noble metal.…”

Tuning Acceptor Length in Photocatalytic Donor‐Acceptor Conjugated Polymers for Efficient Solar‐to‐Hydrogen Energy Conversion

“…Therefore, organic semiconductor photocatalysts have attracted remarkable attention in the past decade. And a variety of organic photocatalysts have been developed, including graphitic carbon nitrides ( g ‐C 3 N 4 ), [ 10‐18 ] covalent organic frameworks (COFs), [ 19‐25 ] conjugated microporous polymers (CMPs), [ 26‐36 ] covalent triazine‐based frameworks (CTFs) [ 37‐43 ] and linear conjugated polymers (LCPs). [ 44‐52 ] Although some of them can achieve hydrogen evolution rate (HER) exceeding 10 mmol·g –1 ·h –1 , [ 22,30‐32,40,47‐49 ] the solar‐to‐hydrogen energy (STH) conversion efficiency is still very low, far from the basic requirement of 10% for their practical application.…”

Recent advances in high-crystalline conjugated organic polymeric materials for photocatalytic CO2conversion

“…Therefore, the CTFs synthesized by ternary eutectic salt showed better crystallinity and photocatalytic performance. 86 2.3.2 Superacid-catalyzed strategy. Under the assistance of a certain amount of superacid, the stacking mode of CTFs will generally change from the AB mode to AA mode, and this transformation in mode will eventually lead to CTFs with relatively high crystallinity, purity and specific surface area.…”