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Law Valentin posted an update 1 week, 1 day ago
These observations regarding the concurrent occurrence of electrochemical and tribological phenomena are vital to further improve the design and performance of taper junctions in similar environments. © 2020 The Authors. Published by WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim.Humic acid, as a natural organic matter, is widely distributed in surface soil, oceans, rivers, and other ecological environments throughout the whole earth ecosystem. Humic acid provides abundant organic carbon and helps to maintain a hydrated, pH and redox buffered environment hosting the soil microbiome. Humic acid is however also a largely ignored polymer material full of exciting functional properties, and its scale is enormous. This perspective article discusses its synthesis and management as a tool to tackle parts of the climate crisis as well its use in technological applications, as made by chemical conversion of agricultural side products to artificial humic acids. © 2020 The Authors. Published by WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim.3D electrode design is normally opted for multiple advantages, however, instability/detachment of active material causes the pulverization and degradation of the structure, and ultimately poor cyclic stability. Here, a dually protected, highly compressible, and freestanding anode is presented for sodium-ion batteries, where 3D carbon nanotube (CNT) sponge is decorated with homogeneously dispersed CoSe2 nanoparticles (NPs) which are protected under carbon overcoat (CNT/CoSe2/C). The 3D CNT sponge delivers enough space for high mass loading while providing high mechanical strength and faster conduction pathway among the NPs. The outer amorphous carbon overcoat controls the formation of solid electrolyte interphase film by avoiding direct contact of CoSe2 with electrolyte, accommodates large volume changes, and ultimately enhances the overall conductivity of cell and assists in transmitting electron to an external circuit. Moreover, the hybrid can be densified up to 11-fold without affecting its microstructure that results in ultrahigh areal mass loading of 17.4 mg cm-2 and an areal capacity of 7.03 mAh cm-2 along with a high gravimetric capacity of 531 mAh g-1 at 100 mA g-1. find more Thus, compact and smart devices can be realized by this new electrode design for heavy-duty commercial applications. © 2020 The Authors. Published by WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim.In recent years, there has been an upsurge in the study of novel and alternative energy storage devices beyond lithium-based systems due to the exponential increase in price of lithium. Sodium (Na) metal-based batteries can be a possible alternative to lithium-based batteries due to the similar electrochemical voltage of Na and Li together with the thousand times higher natural abundance of Na compared to Li. Though two different kinds of Na-O2 batteries have been studied specifically based on electrolytes until now, very recently, a hybrid Na-air cell has shown distinctive advantage over nonaqueous cell systems. Hybrid Na-air batteries provide a fundamental advantage due to the formation of highly soluble discharge product (sodium hydroxide) which leads to low overpotentials for charge and discharge processes, high electrical energy efficiency, and good cyclic stability. Herein, the current status and challenges associated with hybrid Na-air batteries are reported. Also, a brief description of nonaqueous Na-O2 batteries and its close competition with hybrid Na-air batteries are provided. © 2020 The Authors. Published by WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim.Mobile organisms with ability for locomotion and transportation, such as humans and other animals, utilize orchestrated actuation to perform actions. Mimicking these functionalities in synthetic, light-responsive untethered soft-bodied devices remains a challenge. Inspired by multitasking and mobile biological systems, an untethered soft transporter robot with controlled multidirectional locomotion with the ability of picking up, transporting, and delivering cargo driven entirely by blue light is created. The soft robot design is an ensemble of light-responsive liquid crystalline polymers that can harness motion either collectively or individually to obtain a high degree of motion control for the execution of advanced tasks in a dry environment. Through orchestrated motion of the device’s “legs”, single displacement strides, which exceed 4 mm and can be taken in any direction, allow for locomotion around objects. Untethered cargo transportation is demonstrated by a pickup and release mechanism using the device’s “arms”. This strategy demonstrates the constructive harnessing of orchestrated motion in assemblies of established actuators, performing complex functions, mimicking constructive behavior seen in nature. © 2020 The Authors. Published by WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim.Rational design of unique pre-catalysts for highly active catalysts toward catalyzing the oxygen evolution reaction (OER) is a great challenge. Herein, a Co-derived pre-catalyst that allows gradual exposure of CoOOH that acts as the active center for OER catalysis is obtained by both phosphate ion surface functionalization and Mo inner doping. The obtained catalyst reveals an excellent OER activity with a low overpotential of 265 mV at a current density of 10 mA cm-2 and good durability in alkaline electrolyte, which is comparable to the majority of Co-based OER catalysts. Specifically, the surface functionalization produces lots of Co-PO4 species with oxygen vacancies which can trigger the surface self-reconstruction of pre-catalyst for a favorable OER reaction. Density functional theory calculations reveal that the Mo doping optimizes adsorption-free energy of *OOH formation and thus accelerates intrinsic electrocatalytic activity. Expanding on these explorations, a series of transition metal oxide pre-catalysts are obtained using this general design strategy. The work offers a fundamental understanding toward the correlation among surface-structure-activity for the pre-catalyst design. © 2020 The Authors. Published by WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim.