RESUMO
The rational synthesis of carbon nitride materials, ranging from polymeric carbon nitride to nitrogen-doped carbon, by supramolecular preorganization of their monomers is a powerful tool for the design of their morphology and photophysical and catalytic activities. Here we show a new facile and scalable approach for the synthesis of ordered CN materials with excellent photoactivity, which consists of supramolecular interfacial preorganization of CN monomers at the interface of two non-miscible solvents. Molecular dynamic simulations supported by experimental results reveal that an appropriate choice of monomers and solvents leads to the formation of a supramolecular assembly solely at the interface of the solvents. As a proof of concept, we show that the properties of the CN materials after thermal condensation can be tuned by adding an additional monomer to one solvent only. The advantages of the new method are demonstrated here through the tunable morphologies and surface area, the formation of new electronic junctions and high activity as a photocatalyst for hydrogen evolution and pollutant degradation of the CN materials.
RESUMO
Structural modifications in carbon nitrides and related carbon-based materials have been achieved in recent years by organizing their monomers into versatile supramolecular structures that serve as reactants for the high temperature solid-state reaction. To date, the organization is usually carried out in one solvent where the building blocks must be dispersed. Here, we show the utilization of a molecule with both hydrogen bond donor and acceptor sites for constructing hydrogen bonded frameworks in interfacial systems. The chemical and electronic properties of the carbon nitride materials after calcination are strongly altered showing enhanced photocatalytic performance in different model reactions. This work shows a new large-scale pathway for the synthesis of highly photoactive carbon nitride with tailored properties and morphology by employing novel supramolecular assemblies prepared in the interface between two solvents, and furthermore opens new opportunities in the rational design of different carbon-nitrogen based materials utilizing supramolecular structures.
RESUMO
Contamination of groundwater with radioactive substances comprising actinides and lanthanides is a significant environmental hazard and thus the development of selective, sensitive, and easy-to-apply sensors for water-soluble actinide and lanthanide ions is highly sought. We constructed a new selective fluorescent sensor for UO2 2+, Sm3+, and Eu3+ based on a carbon dot (C-dot)-aerogel hybrid prepared through in situ carbonization of 2-thenoyltrifluoroacetone (TTA), a high-affinity heavy metal chelator. The TTA-C-dot-aerogel enabled the detection of UO2 2+ ions, which induced a significant red fluorescence shift, whereas Eu3+ and particularly Sm3+ ions gave rise to pronounced fluorescence quenching. Importantly, the lanthanide/actinide ion-selective TTA-C-dots could be synthesized only in situ inside the aerogel pores, indicating the crucial role of the aerogel host matrix both in enabling the formation of the C-dots and in promoting the adsorption and interactions of the lanthanide and actinide metal ions with the embedded C-dots.
RESUMO
A new hybrid system comprising polydiacetylene (PDA), a chromatic conjugated polymer, embedded within aerogel pores has been constructed. The PDA-aerogel powder underwent dramatic color changes in the presence of volatile organic compounds (VOCs), facilitated through infiltration of the gas molecules into the highly porous aerogel matrix and their interactions with the aerogel-embedded PDA units. The PDA-aerogel composite exhibited rapid color/fluorescence response and enhanced signals upon exposure to low VOC concentrations. Encapsulation of PDA derivatives displaying different headgroups within the aerogel produced distinct VOC-dependent color transformations, forming a PDA-aerogel "artificial nose".
