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This work demonstrates the synthesis of a switchable single-molecule electrochromic device generated by tethering a viologen onto a poly(ionic liquid) (PIL) via an alkyl linker.

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With the rising energy crisis and increasingly serious environmental issues, clean energy sources like fuel cell and lithium–air batteries are attracting the attention of the whole world. The direct fuel cell, especially, is believed to be the quintessential replacement for conventional sources of energy because of its high energy conversion capacity. Electrochemical water splitting has an important role in such sustainable energy technologies. Catalysts play a worthwhile role in water splitting, especially the oxygen evolution reaction (OER). Engineering fine micro/nanostructures with subtle morphologies represents an effective strategy to enhance the activity of the resultant catalyst toward OER through exposing abundant electrochemically active sites. So, here we report a Co3O4@SUS catalyst, the well-defined Co3O4 microrods were successfully anchored onto the stainless steel mesh substrate with the assistance of diethylene­triamine using microwave irradiation, utilizing a commercially available microwave instrument. Co3O4@SUS possesses outstanding catalytic activity toward water oxidation. In water oxidation, the current density of 10 mA cm–2 was achieved at 298 mV overpotential with a low Tafel slope of 105 mV dec–1. In addition to low overpotential, Co3O4@SUS was stable under conditions of continuous O2 evolution for an extended period (24 h). The results show a highly efficient, scalable, and low-cost method for developing highly active and stable OER electrocatalysts in alkaline solution.

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A flexible nanofibrous aerogel with laser-cut perforations was developed for effective sound absorption and insulation. Polyethylene terephthalate (PET) waste bottles were turned into uniform nanofibers (NFs) via an electrospinning technique that were subsequently processed to create a 3D porous network through a freeze-drying method. Reinforcing the aerogel with glutaraldehyde-cross-linked poly(vinyl alcohol) (PVA) allowed mechanical flexibility resulting in a Young's modulus of 2.28 × 10 −2 MPa. The highly tortuous pore structure produced by the densely packed nanosized fibers permitted a noise reduction coefficient (NRC) of 0.37 (at areal density of 465 g m −2 ). Likewise, the overall transmission loss is increased as nanofibers are used instead of microfibers. In terms of sound insulation performance, a standard transmission class (STC) of 6.1 dB, which is about 10 times that of a commercial polyurethane-based acoustic foam, is displayed by the PETNF aerogel. Moreover, the creation of perforations further enhanced the material's sound absorption such that an NRC of 0.54 (at areal density of 930 g m −2 ) was obtained, which is similar to or greater than that of most fiber-based acoustic materials previously reported. By changing the perforation diameter, one can tune its overall acoustic performance. In addition, utilizing a waste-derived material for noise pollution control alleviates the generation of plastic waste that is detrimental to the environment.