Three o-phenylendiamine (OPD) derivatives, containing 4-chloro-7-nitrobenzo[c][1,2,5]oxadiazole (NBD-OPD), rhodamine (RB-OPD), and 1,8-naphthalimide (NAP-OPD) moieties, were prepared and tested as phosgene chemosensors. Unlike previously described methods to sense this toxic agent, which rely on chemical processes that transform alcohols and amines to respective phosphate esters and phosphoramides, the new sensors operate through a benzimidazolone-forming reaction between their OPD groups and phosgene. These processes promote either naked eye visible color changes and/or fluorescence intensity enhancements in conjunction with detection limits that range from 0.7 to 2.8 ppb. NBD-OPD and RB-OPD-embedded polymer fibers, prepared using the electrospinning technique, display distinct color and fluorescence changes upon exposure to phosgene even in the solid state.

Because of the current shortage of first-generation phosgene sensors, increased attention has been given to the development of fluorescent and colorimetric based methods for detecting this toxic substance. In an effort focusing on this issue, we designed the new, second-generation phosgene chemosensor 1 and demonstrated that it undergoes a ring-opening reaction with phosgene in association with color and fluorescent changes with a detection limit of 3.2 ppb. Notably, in comparison with the first-generation sensor RB-OPD, 1 not only undergoes a much faster response toward phosgene with an overall response time within 2 min, but it also generates no byproducts during the sensing process. Finally, sensor 1 embedded nanofibers were successfully fabricated and used for accurate and sensitive detection of phosgene.

The photostability of donor–acceptor (D–A) polymers remains a critical issue despite recent improvements in the power conversion efficiencies (PCEs) of organic photovoltaic (OPV) cells. We report the synthesis of three highly photostable polymers (PDTBDT-BZ, PDTBDT-BZF, and PDTBDT-BZF2) and their suitability for use in high-performance OPV cells. Under 1 sunlight of illumination in air for 10 h, these polymer films demonstrated remarkably high photostability compared to that of PTB7, a representative polymer in the OPV field. While the PDTBDT-BZ, PDTBDT-BZF, and PDTBDT-BZF2 polymer films maintained 97, 90, and 96% photostability, respectively, a PTB7 film exhibited only 38% photostability under the same conditions. We ascribed the high photostability of the polymers to both the intrinsically photostable chemical moieties and the dense packing of alkyl side chains and planar backbone polymer chains, which prevents oxygen diffusion into the PDTBDT-BZ films. This work demonstrates the high photostability of planar PDTBDT-BZ series polymers composed of photostable DTBDT and BZ moieties and suggests a design rule to synthesize highly photostable photovoltaic materials.

Hydrogen evolution reaction (HER) is of importance in energy conversion processes. This paper reports the facile synthesis of iridium/iridium oxide nanofibers (Ir/IrO2NFs) with diverse Ir and IrO2 relative composition ratios and their electrocatalytic HER activities. Highly porous Ir/IrO2NFs are simply synthesized via electrospinning and the following calcination at various temperatures (300–900 °C). Different calcination temperature alters the actual composition of Ir/IrO2NFs: The higher the temperature, the greater IrO2 content exists. The HER activity of Ir/IrO2NFs is examined in 1 M H2SO4. Ir/IrO2NF calcined at 300 °C exhibits the best HER activity in terms of the onset potential, overpotential generating 50 mA cm–2, turnover frequency, Tafel slope along with the decent stability for 5 h; the HER performance of this material even exceeds that of platinum, a benchmark HER catalyst. As the IrO2 content in Ir/IrO2NFs increases with a higher calcination temperature, the HER activity decreases. Ir/IrO2NF calcined at 900 °C consists of only IrO2 and presents the worst activity. DFT calculations show that hydrogen atom adsorption on metallic Ir (not IrO2) resembles that on Pt: similar adsorption energy and adsorbate–substrate distance. Both the experimental and theoretical results clearly demonstrate that metallic Ir rather than IrO2 is a good HER catalytic platform.

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