A novel kind of quantum dots, sulfur quantum dots (S dots), is synthesized by simply treating sublimated sulfur powders with alkali using polyethylene glycol-400 as passivation agents. The synthesized S dots exhibit excellent aqueous dispersibility, eminent photostability and temperature dependent photoluminescence (PL). An "assemble-fission" mechanism is proposed for the S dots formation in which "assembling" and "fission" are involved and contest each other. The ultimate morphologies of the S dots are dependent on the balance of the two forces. Guided by the assemble-fission mechanism, weakening the assembling effect is beneficial for obtaining monodisperse S dots, which can be achieved by pretreating of sulfur powder with nitric acid. PL wavelength of the S dots has been successfully tuned between green and blue light (from 550 to 440 nm) by simply controlling reaction time. A satisfactory quantum yield of 3.8% is obtained. Significant electrochemiluminescence of the S dots is observed in an annihilation reaction. Chemiluminescence from the S dots has been observed by direct oxidation. Taking advantage of unique and inherent antimicrobial activity of the sulfur particles, it is believed that this new emerging luminescent nanomaterial is highly promising in the development of new types of optoelectronic devices and tracer for live cells, in vivo imaging and diagnostics.

Porous liquids (PLs), an emerging kind of liquid materials with permanent porosity, have attracted increasing attention in gas capture. However, directly turning metal−organic frameworks (MOFs) into PLs via a covalent linkage surface engineering strategy has not been reported. Additionally, challenges including reducing the cost and simplifying the preparation process are daunting. Herein, we proposed a general method to transform Universitetet i Oslo (UiO)-66-OH MOFs into PLs by surface engineering with organosilane (OS) and oligomer species via covalent bonding linkage. The oligomer species endow UiO-66-OH with superior fluidity at room temperature. Meanwhile, the resulting PLs showed great potential in both CO 2 adsorption and CO 2 /N 2 selective separation. The residual porosity of PLs was verified by diverse characterizations and molecular simulations. Besides, CO 2 selective capture sites were determined by grand canonical Monte Carlo (GCMC) simulation. Furthermore, the universality of the covalent linkage surface engineering strategy was confirmed using different classes of oligomer species and another MOF (ZIF-8-bearing amino groups). Notably, this strategy can be extended to construct other PLs by taking advantages of the rich library of oligomer species, thus making PLs promising candidates for further applications in energy and environment-related fields, such as gas capture, separation, and catalysis.

No abstract

Liquid-like nanoparticle organic hybrid materials with core/canopy/corona were used as fillers in Pebax-1657 matrix to fabricate mixed-matrix membranes. The effect of composite core composition on CO2/N2 separation performance was systematically investigated.