Covalent triazine frameworks(CTFs)are a class of unique two-dimensional nitrogen-rich triazine framework with adjustable chemical and electronic structures,rich porosity,good stability and excellent semiconductivity,which enable great various applications in efficient gas/molecular adsorption and separation,energy storage and conversion,especially photo-and electrocatalysis.Different synthesis strategies strongly affect the morphology of CTFs and play an important role in their structure and properties.In this concept,we provide a comprehensive and systematic review of the synthesis methods such as ionothermal synthesis,phosphorus pentoxide catalytic method,polycondensation and ultra-strong acid catalyzed method,and applications of CTFs in photo-and electro-catalysis.Finally we offer some insights into the future development progress of CTFs materials for catalytic applications.
Covalent triazine framework nanosheets (CTF NSs),an emerging class of two-dimensional nanomaterials,have received great attention due to their abundant active sites,permanent porosity,molecular structural diversity,superior chemical/thermal stability,and short charge diffusion path,enabling technological breakthroughs in a myriad of applications. The forefront developments and applications of CTF NSs as photocatalysts and electrochemical electrodes have conferred superior performance and made great impact in the field of energy and advanced catalysis. This forward-looking review aims to summarize the research trends,synthesis,properties of CTF NSs and their CTF counterpart,and highlight their progress in applications with respect to energy storage and conversion devices. Finally,the current challenges and future perspectives for CTF NSs are also presented.
The efficient synthesis of ultrathin crystalline twodimensional(2D)polymers with well-defined repeating units is essential to realize their broad applications but remains a great challenge.Herein,we report a new strategy to directly synthesize a series of few-layer 2D triazine-based polymers(2DTPs)via trimerization reaction of aromatic aldoximes in one step with a high yield of 85%using AlCl3 as catalyst under solvent-free conditions.The obtained 2D-TPs show high crystallinity,a lateral size of several micrometers,an ultrathin thickness less than 2 nm,and good dispersibility and processability.Through semi-in situ and detailed control experiments,we reveal that the 2D polymerization reaction is a two-step process of dehydration and then cyclotrimerization,and AlCl3 acts as not only catalyst but also an in situ generated template for promoting the formation of 2D-TPs.When explored as a new polymeric anode for potassium-ion batteries,the 2D-TP displayed an extraordinary reversible specific capacity of 356 mAh g^(−1)at 0.05 A g^(−1),which is among the best performances ever reported,outstanding rate capability(153 mAh g^(−1)at 1 A g^(−1)),and excellent cycling stability with 95.1%capacity retention after 1000 cycles at 1 A g^(−1).
Pt nanoparticles(PtNPs)as active species have always been considered as one of the best semiconductor materials for photocatalytic hydrogen production.In this study,a Schottky heterojunction has been successfully constructed by evenly loading ultrafine PtNPs onto a triazine-based covalent organic frameworks(COFs).This strategy maintained the high activity of these ultra-small PtNPs while maximizing the utilization of the Pt active sites.The fabricated PtNPs@covalent triazine-based framework-1(CTF-1)composite accomplished a significantly high rate of hydrogen evolution(20.0 mmol·g^(−1)·h^(−1),apparent quantum efficiency(AQE)=7.6%,atλ=450 nm)with 0.40 wt.%Pt loading,giving rise to a 44-fold-increase in the efficiency of the photocatalytic hydrogen production compared to the pristine CTF-1.Theoretical calculations revealed that the strong electron transfer(Q(Pt)=−0.726 qe,in the analysis of Bader charge,Q(Pt)is the charge quantity transferred from Pt cluster to CTF-1,and qe is the unit of charge transfer quantity)between PtNPs and CTF-1 triggers a strong interaction,which makes PtNPs being firmly attached to the structure of CTF-1,thereby enabling high stability and excellent hydrogen production efficiency.Importantly,the hydrogen binding free energy(ΔGH*)of PtNPs@CTF-1 is much lower than that of the unmodified CTF-1,leading to a much lower intermediate state and hence a significant improvement in photocatalytic performance.The overall findings of this work provide a new platform to incorporate metallic NPs into COFs for the design and fabrication of highly efficient photocatalysts.
