Co(3)O(4) with three different crystal plane structures - cubes bounded by {001}planes, truncated octahedra enclosed by {111} and {001} planes, and octahedra with exposed {111}planes - is synthesized using a very simple one-step hydrothermal method. The three kinds of Co(3)O(4) exhibit significantly different electrochemical performances and the effect of different exposed crystal planes on the electrochemical performance of Co(3)O(4) is comprehensively studied.

The effects of nanoconfinement on the structural phase transition, H 2 release and uptake, and the emission of toxic diborane (B 2 H 6 ) on desorption of LiBH 4 have been comprehensively investigated in the presence of various porous hard carbon templates at a variety of pore sizes. Calorimetry signatures of both the structural phase transition and melting of nanoconfined LiBH 4 shifted to a lower temperature with respect to the bulk, finally vanishing below a pore size around 4 nm. The desorption of LiBH 4 confined in these nanoporous carbons shows a systematic and monotonic decrease in the desorption temperature and concomitantly, mass spectroscopic analysis indicated a gradual reduction of the partial pressure of B 2 H 6 with decreasing pore size, suggesting that formation of stable closoborane salts may be avoided by interrupting the reaction pathway. This represents a major breakthrough in the reversibility of boron-based hydrogen storage systems, where capacity is lost in the formation of stable B-H species on cycling. Different carbon preparation techniques suggest that the confinement size, and not solely surface interactions, may be used to tune the properties of complex hydrides for kinetic and reaction pathway improvements for hydrogen storage applications.

Rechargeable Li-O2 batteries have been considered as the most promising chemical power owing to their ultrahigh specific energy density. But the sluggish oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) result in the high overpotential (~1.5V), the poor rate capability and even the short cycle life, which critically hinder their practical applications. Herein, we propose a synergistic strategy to boost the electrocatalytic activity of Co3O4 nanosheets for Li-O2 battery by tuning the inner oxygen vacancies and the exterior Co 3+ /Co 2+ ratio which have been identified by Raman spectroscopy, X-ray photoelectron spectroscopy and X-ray Absorption Near Edge Structure spectroscopy. Operando X-ray diffraction and ex-situ Scanning Electron Microscope are used to probe the evolution of the discharge product. In comparison with bulk Co3O4, the cells catalyzed by Co3O4 nanosheets show a much higher initial capacity (~24051.2mAh g -1 ), better rate capability (8683.3mAh g -1 @400mA g -1 ) and cycling stability (150 cycles@400mA g -1 ), and lower overpotential. The large enhancement of the electrochemical performances can be greatly attributed to the synergistic effect of the architectured 2D nanosheets, the oxygen vacancies and Co 3+ /Co 2+ difference between the surface and the interior.Moreover, the addition of LiI in the electrolyte can further reduce the overpotential making the battery more practical. This study offers some insights into designing high performance electrocatalysts for Li-O2 batteries through the combination of the 2D nanosheets architecture, oxygen vacancy and surface electronic structure regulation.

The wetting and decomposition behavior of LiBH 4 has been investigated in the presence of highly ordered nanoporous hard carbon (NPC) with hexagonally packed 2 nm diameter columnar pores. Calorimetry, X-ray diffraction, and IR spectroscopy measurements confirm that the LiBH 4 within the pores is amorphous. The confinement of LiBH 4 in such small pores results in the disappearance of the low-temperature structural phase transition, the melting transition, and also the significant decrease of the onset desorption temperature from 460 to 220 °C with respect to bulk LiBH 4 , a lower temperature than observed in larger pore sizes in the literature. Most importantly, our results suggest that diborane release is suppressed or eliminated in the decomposition of noncrystalline LiBH 4 . Tight nanoconfinement may therefore mitigate both safety concerns and loss of active material in borohydride-based hydrogen storage systems.

Radioresistance is one of the undesirable impediments in hypoxic tumors, which sharply diminishes the therapeutic effectiveness of radiotherapy and eventually results in the failure of their treatments. An attractive strategy for attenuating radioresistance is developing an ideal radiosensitization system with appreciable radiosensitization capacity to attenuate tumor hypoxia and reinforce radiotherapy response in hypoxic tumors. Therefore, we describe the development of Gd-containing polyoxometalates-conjugated chitosan (GdW@CS nanosphere) as a radiosensitization system for simultaneous extrinsic and intrinsic radiosensitization, by generating an overabundance of cytotoxic reactive oxygen species (ROS) using high-energy X-ray stimulation and mediating the hypoxia-inducible factor-1a (HIF-1a) siRNA to down-regulate HIF-1α expression and suppress broken double-stranded DNA self-healing. Most importantly, the GdW@CS nanospheres have the capacity to promote the exhaustion of intracellular glutathione (reduced GSH) by synergy W-triggered GSH oxidation for sufficient ROS generation, thereby facilitating the therapeutic efficiency of radiotherapy. As a result, the as-synthesized GdW@CS nanosphere can overcome radioresistance of hypoxic tumors through a simultaneous extrinsic and intrinsic strategy to improve radiosensitivity. We have demonstrated GdW@CS nanospheres with special radiosensitization behavior, which provides a versatile approach to solve the critical radioresistance issue of hypoxic tumors.

Noble-metal-free bifunctional cathode catalysts, which can promote both the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER), are quite necessary for lithium−air batteries. In this study, we propose a novel strategy to improve the catalytic performance of CoO through the integration with the dotted carbon species and oxygen vacancies. We have successfully prepared carbon-dotted defective CoO with oxygen vacancies (CoO/C) by sintering the pink precursors obtained from the ethanol-mediated Co(Ac) 2 •4H 2 O. In comparison with the commercial or oxygen-vacancies-only CoO, the cycling stability, the initial capacity, and the rate capability of CoO/C-catalyzed cathode have all been greatly enhanced, and the overpotential has also been decreased, which can be attributed to the synergetic effect of the dotted carbon species and oxygen vacancies on both ORR and OER. Oxygen vacancies can enhance the mobility of e − and Li + and bind to O 2 and Li 2 O 2 as active sites. The dotted carbon species not only improve the conductivity of CoO but also stabilize the oxygen vacancies during ORR/OER. In addition, our further investigation on the evolution of the morphology and phase composition of CoO/C and commercial CoO based cathodes under different charge/discharge states confirms that CoO/ C can largely accelerate the formation and decomposition of Li 2 O 2 during discharge−charge cycles.

Co substitution has been extensively used to improve the electrochemical performances of cathode materials for sodium-ion batteries (SIBs), but the role of Co has not been well understood. Herein, we have comprehensively investigated the effects of Co substitution for Ni on the structure and electrochemical performances of Na0.7Mn0.7Ni0.3-xCoxO2 (x = 0, 0.1, 0.3) as cathode materials for SIBs. In comparison with the Co-free sample, the high-rate capability and cycle performance have been greatly improved by the substitution of Co, and some new insights into the role of Co have been proposed for the first time. With the substitution of Co(3+) for Ni(2+) the lattice parameter a decreases; however, c increases, and the d-spacing of the sodium-ion diffusion layer has been enlarged, which enhances the diffusion coefficient of the sodium ion and the high-rate capability of cathode materials. In addition, Co substitution shortens the bond lengths of TM-O (TM = transition metal) and O-O due to the smaller size of Co(3+) than Ni(2+), which accounts for the decreased thickness and volume of the TMO6 octahedron. The contraction of TM-O and O-O bond lengths and the shrinkage of the TMO6 octahedron improve the structure stability and the cycle performance. Last but not least, the aliovalent substitution of Co(3+) for Ni(2+) can improve the electronic conductivity during the electrochemical reaction, which is also favorable to enhance the high-rate performance. This study not only unveils the role of Co in improving the high-rate capability and the cycle stability of layered Na0.7Mn0.7Ni0.3-xCoxO2 cathode materials but also offers some new insights into designing high performance cathode materials for SIBs.

When fabricating Li‐rich layered oxide cathode materials, anionic redox chemistry plays a critical role in achieving a large specific capacity. Unfortunately, the release of lattice oxygen at the surface impedes the reversibility of the anionic redox reaction, which induces a large irreversible capacity loss, inferior thermal stability, and voltage decay. Therefore, methods for improving the anionic redox constitute a major challenge for the application of high‐energy‐density Li‐rich Mn‐based cathode materials. Herein, to enhance the oxygen redox activity and reversibility in Co‐free Li‐rich Mn‐based Li1.2Mn0.6Ni0.2O2 cathode materials by using an integrated strategy of Li2SnO3 coating‐induced Sn doping and spinel phase formation during synchronous lithiation is proposed. As an Li+ conductor, a Li2SnO3 nanocoating layer protects the lattice oxygen from exposure at the surface, thereby avoiding irreversible oxidation. The synergy of the formed spinel phase and Sn dopant not only improves the anionic redox activity, reversibility, and Li+ migration rate but also decreases Li/Ni mixing. The 1% Li2SnO3‐coated Li1.2Mn0.6Ni0.2O2 delivers a capacity of more than 300 mAh g−1 with 92% Coulombic efficiency. Moreover, improved thermal stability and voltage retention are also observed. This synergic strategy may provide insights for understanding and designing new high‐performance materials with enhanced reversible anionic redox and stabilized surface lattice oxygen.