No abstract

The spread of wearable and flexible electronics devices has been accelerating in recent years for a wide range of applications. Development of an appropriate flexible power source to operate these flexible devices is a key challenge. Supercapacitors are attractive for powering portable lightweight consumer devices due to their long cycle stability, fast charge-discharge cycle, outstanding power density, wide operating temperatures and safety. Much effort has been devoted to ensure high mechanical and electrochemical stability upon bending, folding or stretching and to develop flexible electrodes, substrates and overall geometrically-flexible structures. Supercapacitors have attracted considerable attention and shown many applications on various scales. In this review, we focus on flexible structural design under six categories: paper-like, textile-like, wire-like, origami, biomimetics based design and micro-supercapacitors. Finally, we present our perspective of flexible supercapacitors and emphasize current technical difficulties to stimulate further research.

Ordered mesoporous carbons (OMCs) possess great advantages, such as large surface area, uniform pore distribution, high porosity, and physical and chemical stability. However, the monotonic and long porous channels in OMCs hinder their further application, especially in energy storage. Here, we synthesized mesoporous carbon hollow spheres (MCHSs) with a "Dualtemplating method" using dandelion-like silica spheres (DSSs) as the template.Through the dual-templating method, the MCHSs directly replicated the mesoporous edge of DSSs as a thick mesoporous shell but substituted the clogged central core with hollow-core. The combined structure with mesoporous carbon spheres and hollow-core has various advantages over conventional OMCs.The radial and hierarchical pores in the sphere provide a large surface area (1319 m 2 g À1 ), short diffusion path, and open-pore that facilitates ion transfer to any direction. Simultaneously, the hollow sphere carved in the center of the MCHSs allows space for the improvement of ion mobility and electrolyte retention. Also, the dense structure of the MCHSs allows more compact packing and high tap density when MCHSs were applied as an electrode. The MCHSs exhibit high specific capacitance and present a well-developed EDLC shape at all scan rates (10 to 1000 mV s À1 ), the results show a superior electrochemical performance compared with other recent mesoporous carbon allotropes.

Colorimetric chemosensors are widely employed for in-field analysis to detect transition metal ions in real-time with the naked eye. Colorimetric chemosensors have attracted considerable attention because they can conveniently provide quantitative and qualitative information at a low cost. However, the development of colorimetric chemosensors for multiple-ion sensing where metal cations coexist has been limited. For this reason, we developed a new type of transition metal ion sensing material by selectively replacing functional groups on (diphosphine)Pt(dmit) molecules. The terminal groups of the diphosphine ligand were successfully substituted by the cyclohexyl groups, increasing the electron density of the thione moiety. Due to the electron donation ability of the cyclohexyl terminal groups, the proposed chemosensing material was able to selectively detect the mixture of Hg2+, Cu2+, and Ag+ in the presence of many types of interfering cations. To gain insight into the binding mechanisms between the metal ions and the developed (dchpe)Pt(dmit) molecule, density functional theory calculations were also performed.

In recent decades, concerns about increasing biological and environmental contamination have necessitated the development of chemosensors with high selectivity, sensitivity, and cost-effectiveness. In principle, the sensing performance can be affected by the functional group(s) of receptor, the charge of the metal ion(s), and the electron configuration of the sensing molecule(s)e and metal ion(s). Fine controlling of the substituents can influence the electron density of the receptor to enhance the binding affinity to metal ions, which is an effective way to improve the photophysical properties of the sensors. This review explores the effect of functional group modification on the performance of various chemosensors represented by Pt(dithiolene)-based complexes (2012–2021). Then, recently developed Schiff base chemosensors (2014–2021) are discussed. The Schiff base is a good platform for controlling electron configuration due to a facile synthesis of various organic structures (aldehyde or ketone groups with primary amine derivatives). The discussion focuses on the detection type, physicochemical and optical properties, and applications of these chemosensors.