Keywords: Li-ion batteries, intercalation cathodes, disordered rock salt, Li 2 VO 2 F Advanced cathode materials with superior energy storage capability are highly demanded for mobile and stationary applications. The inherent structural feature of Li + hosts is critical for the battery performance. High-capacity conversion cathode materials often encounter large voltage hysteresis (low energy efficiency) accompanied with the structural reconstruction.The current commercial cathode materials are still dominated by intercalation materials with intrinsic structural integrity for accommodating Li + . However, the known intercalation materials have limited theoretical capacity (< 300 mAh g -1 ).  In addition, structural transition/degradation have often been observed for the common intercalation hosts with ordered Li + / transition metal (TM) lattice sites. Antisite disorder (Li + sites/layers occupied by TM ions) in olivines can block the one-dimensional Li + diffusion path. The activation barrier for Li + diffusion in layered oxides is sensitive to the Li-content, the spacing of the
Hierarchical dendritic gold microstrutures (HDGMs) with secondary and tertiary branches are directly electrodeposited on an indium tin oxide (ITO) substrate without the use of any templates, surfactants, or stabilizers. The effects of electrodeposition potential and HAuCl 4 concentration on the formation of HDGMs and time-dependent morphological evolution are investigated in detail. A diffusion-limited aggregation (DLA) mechanism is used to explain the formation of HDGMs. Typically, the as-synthesized HDGMs exhibited much higher electrocatalytic activity and enhanced stability toward ethanol electrooxidation compared to bulk gold electrode and also display great Raman enhancement activity with the detection limit of 10 -12 M for rhodamine 6G. The surface of HDGMs possesses hydrophobicity even without modification with lowsurface-energy coatings and has a remarkable superhydrophobic property even in corrosive solutions over a wide pH range after the treatment with n-dodecanethiol. In addition, (super)oleophobicity is successfully obtained by modification with 1H,1H,2H,2H-perfluorodecanethiol.
UV light-induced surface-initiated atom-transfer radical polymerization (ATRP) was reported. This method uses TiO 2 nanoparticles as photoactive materials to reduce Cu(II)/L to a Cu(I)/L complex under UV irradiation by a one-electron transfer process for ATRP with multiple usage of monomer solutions. The growth of polymer brushes can be manipulated by either varying the content of photoactive materials or regulating the irradiation intensity, thereby yielding polymer brushes with controllable thickness, composition, and architecture. P olymer brushes produced by controlled or living surfaceinitiated radical polymerization 1,2 provide a superior route for surface functionalization, such as creation of smart surfaces, 3−5 antibiofouling materials, 6,7 and lubrication. 8 Compared with various controlled radical polymerization techniques 9 and organic polymer synthesis strategies, 10 atomtransfer radical polymerization (ATRP) 11−14 facilitates the construction of diverse polymer assemblies. 15−18 Generally, a Cu(I)−ligand complex and high monomer concentration are necessary to maximize polymer growth, 19−21 which highly relies on the reversible redox activation/deactivation of Cu(I)/ Cu(II). Control over the Cu(I)/Cu(II) ratio is important to obtain fast a polymerization rate while prolonging the lifetime of propagation chains. 22,23 The scope of ATRP has been expanded to external stimulusinduced polymerizations, 24,25 such as in electrochemically mediated ATRP (eATRP) for controlling polymerization by the electrically one-electron reduction of air-stable Cu(II). 26,27 We extended the eATRP technique to surface-initiated eATRP for controllable fabrication of surface-attached polymer brushes. 28 External visible light-stimulated living radical polymerization has been proposed through the excited Ir(III) species to reduce an alkyl bromide initiator for alkyl radical formation to initiate polymerization, 29,30 click reaction, 31,32 light-mediated atom-transfer radical addition, 33 and photoiniferter-mediated surface attached polymers formation. 34 The key to external stimulus-induced polymerization is continuous in situ generation of the activator catalyst. In this report, we propose a novel approach to achieve surface-initiated ATRP with multiple usage of monomer solutions, wherein the polymerization activators, Cu(I)−ligand, can be continuously generated from a photochemical reduction process by the excited electrons under ultraviolet (UV) illumination that uses the TiO 2 nanoparticle as the photosensitive material. Scheme 1(b) displays the mechanism of UV light-induced ATRP. A commercially available TiO 2 nanoparticle, P25, was
This review starts with a brief introduction to TiO 2 nanotubes (NTs), and then discusses in more detail how to optimize the structure of TiO 2 NTs for the fabrication of highly efficient solar cells, including the controllable fabrication of perfectly aligned TiO 2 NTs, optimizing the tube parameters, strategies of sensitization, improvement of the interface adhesion in polymer/TiO 2 solar cells and how to make devices flexible. Some key challenges and perspectives for future research are also tentatively discussed.
The utilization of intermittent renewable energy sources needs low-cost, reliable energy storage systems in the future. Among various electrochemical energy storage systems, redox flow batteries (RFBs) are promising with merits of independent energy storage and power generation capability, localization flexibility, high efficiency, low scaling-up cost, and excellent long charge/discharge cycle life. RFBs typically use metal ions as reacting species. The most exploited types are all-vanadium RFBs (VRFBs). Here, we discuss the core components for the VRFBs, including the development and application of different types of membranes, electrode materials, and stack system. In addition, we introduce the recent progress in the discovery of novel electrolytes, such as redox-active organic compounds, polymers, and organic/inorganic suspensions. Versatile structures, tunable properties, and abundant resources of organic-based electrolytes make them suitable for cost-effective stationary applications. With the active species in solid form, suspension electrolytes are expected to provide enhanced volumetric energy densities.
New high‐capacity intercalation cathodes of Li2VxCr1−xO2F with a stable disordered rock salt host framework allow a high operating voltage up to 3.5 V, good rate performance (960 Wh kg−1 at ≈1 C), and cycling stability.
Brushing up on polymers: A difference in electrochemical potential allows surface‐initiated atom‐transfer radical polymerization on a sandwiched metal substrate using microliter volumes. CuI activators are continuously generated and diffuse to the initiator‐modified substrate (see scheme), while CuII deactivators maintain polymerization. Polymer‐brush gradients of SPMA and complex shapes were produced using this method.
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