Macrocyclic Arenes-Based Conjugated Macrocycle Polymers for Highly Selective CO2 Capture and Iodine Adsorption.

Incorporating synthetic macrocycles with unique structures and distinct conformations into conjugated macrocycle polymers (CMPs) can endow the resulting materials with great potentials in gas uptake and pollutant adsorption. Here, four CMPs (CMP-n, n=1-4) capable of reversibly capturing iodine and efficiently separating carbon dioxide are constructed from per-triflate functionalized leaning tower[6]arene (LT6-OTf) and [2]biphenyl-extended pillar[6]arene (BpP6-OTf) via Pd-catalyzed Sonogashira-Hagihara cross-coupling reaction. Intriguingly, owing to the appropriate cavity size of LT6-OTf and the numerous aromatic rings in the framework, the newly designed CMP-4 possesses an outstanding I2 affinity with a large uptake capacity of 208 wt % in vapor and a great removal efficiency of 94 % in aqueous solutions. To our surprise, with no capacity to accommodate nitrogen, CMP-2 constructed from BpP6-OTf is able to specifically capture carbon dioxide at ambient conditions.

Polyoxometalate-viologen photochromic hybrids for rapid solar ultraviolet light detection, photoluminescence-based UV probing and inkless and erasable printing.

In this work, a new crystalline polyoxometalate-viologen hybrid, (Pbpy)(Me2NH2)3[PW11ZnO40] (1: Pbpy = 1,1'-[1,4-phenylenebis-(methylene)]bis(4,4'-bipyridinium)), has been synthesized. It showed efficient ultraviolet light detection ability with an obvious colour change from pale yellow to blue and fast response with ultraviolet intensity as low as 0.006 mW cm-2 in narrow-band UV regions. The POM-viologen-based film of 1 has also been readily prepared on quartz substrates using a drop casting method and could exhibit different levels of colour changes under sunlight irradiation at different local times on a sunny day, indicating its potential to be used as a portable device for solar ultraviolet light detection. Ultraviolet light detection is not only reflected in colour changes, but also accompanies the photoluminescence phenomenon. The fluorescence intensity decreased with the increase of UV intensity, and when irradiated with an ultraviolet xenon lamp (8 mW cm-2) for about 5 min, the fluorescence intensity was almost completely quenched. The compound has the potential to achieve fluorescence based UV probing. The powdered sample of compound 1 could also be deposited in paper simply by coating it with a solution of ethanol. The paper can be used as an inkless and erasable print medium, which was found to remain clear for 11 d in the dark under an ambient atmosphere and was also reusable when erased.

Carbon-armored Co9S8 nanoparticles as all-pH efficient and durable H2-evolving electrocatalysts.

Splitting water to produce hydrogen requires the development of non-noble-metal catalysts that are able to make this reaction feasible and energy efficient. Herein, we show that cobalt pentlandite (Co9S8) nanoparticles can serve as an electrochemically active, noble-metal-free material toward hydrogen evolution reaction, and they work stably in neutral solution (pH 7) but not in acidic (pH 0) and basic (pH 14) media. We, therefore, further present a carbon-armoring strategy to increase the durability and activity of Co9S8 over a wider pH range. In particular, carbon-armored Co9S8 nanoparticles (Co9S8@C) are prepared by direct thermal treatment of a mixture of cobalt nitrate and trithiocyanuric acid at 700 °C in N2 atmosphere. Trithiocyanuric acid functions as both sulfur and carbon sources in the reaction system. The resulting Co9S8@C material operates well with high activity over a broad pH range, from pH 0 to 14, and gives nearly 100% Faradaic yield during hydrogen evolution reaction under acidic (pH 0), neutral (pH 7), and basic (pH 14) media. To the best of our knowledge, this is the first time that a transition-metal chalcogenide material is shown to have all-pH efficient and durable electrocatalytic activity. Identifying Co9S8 as the catalytically active phase and developing carbon-armoring as the improvement strategy are anticipated to give a fresh impetus to rational design of high-performance noble-metal-free water splitting catalysts.

Porous titania with heavily self-doped Ti3+ for specific sensing of CO at room temperature.

Semiconductor-based sensors have played an important role in efficient detection of combustible, flammable, and toxic gases, but they usually need to operate at elevated temperatures (200 °C or higher). Although reducing the operation temperature down to room temperature is of practical significance, it is still a huge challenge to fabricate room temperature sensors with a low cost. Here we show a novel "self-doping" strategy to overcome simultaneously both difficulties of "high resistance" and "low reaction rate", which have always been encountered for room-temperature operation of semiconductor-based sensors. In particular, a porous crystalline titania with heavily self-doped Ti(3+) species has been prepared by using a porous amorphous TiO2 and urea as the starting materials. The resulting Ti(3+) self-doped TiO2 material serves as an efficient room-temperature gas-sensing material for specific CO detection with fast response/recovery. The self-dopant (Ti(3+)) in the titania material has proved to decrease the resistance of TiO2 significantly on the one hand and to increase the chemisorbed oxygen species substantially, thus enhancing the surface reaction activity on the other. Such a self-doping concept is anticipated to give a fresh impetus to rational design of room-temperature sensing devices with low costs.