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Manganese dioxide (MnO 2 ) with a-, b-and d-type structures was controllably synthesized by hydrothermal treatment of an acidic solution of KMnO 4 containing different concentrations of ions at 160 C. The effects of metallic cations, H + and anions on the structures and morphologies of MnO 2 were investigated systematically. The experimental results indicated that cations played a significant part in the formation of MnO 2 with different structures. When K + ions were in competition with H + ions in solution, different MnO 2 structures were formed. a-MnO 2 was formed when the amount of K + was higher than the amount of H + , whereas a higher amount of H + was favorable for the growth of b-MnO 2 structures. When the concentration of K + was much greater than that of H + , d-MnO 2 was obtained. Possible formation mechanisms are proposed based on a series of controlled experiments. The electrochemical properties of supercapacitors based on different types of MnO 2 electrodes were investigated in detail. The specific capacitance measured for MnO 2 strongly depended on the crystallographic structure and decreased in the order a-MnO 2 > d-MnO 2 > b-MnO 2 at a current density of 0.5 A g À1 . A specific capacitance of 535 F g À1 was obtained for a-MnO 2 , but was only 155 F g À1 for b-MnO 2 . a-MnO 2 was more suitable for use as the working electrode at high current densities. Both a-and d-MnO 2 had a poor cycling performance after 3000 cycles, whereas b-MnO 2 showed good stability, maintaining a cycling efficiency of 80% after under the same conditions.

Ordered WO 3 nanowire arrays on carbon cloth (WNCC) conductive substrates are successfully prepared by a facile hydrothermal method. The as-prepared samples were characterized by XRD, SEM and TEM and directly functionalized as supercapacitor (SC) and lithium-ion battery (LIB) electrodes without using any ancillary materials such as carbon black or binder. The unique structural features endow them with excellent electrochemical performance. The SCs demonstrate high specific capacitance of 521 F g À1 at 1 A g À1 and 5.21 F cm À2 at 10 A cm À2 and excellent cyclic performance with nearly 100% capacity retention after 2000 cycles at a current density of 3 A g À1 . All-solid-state SCs based on the integrated electrodes are also presented, exhibiting high flexibility without obvious performance declination at different bending states. A high capacity of 662 mA h g À1 after 140 cycles at a 0.28 C rate and excellent rate capabilities are also obtained for LIBs due to the unique structures of the integrated electrodes.

Zn-ion hybrid supercapacitors (SCs) are considered as promising energy storage owing to their high energy density compared to traditional SCs. How to realize the miniaturization, patterning, and flexibility of the Zn-ion SCs without affecting the electrochemical performances has special meanings for expanding their applications in wearable integrated electronics. Ti3C2Tx cathode with outstanding conductivity, unique lamellar structure and good mechanical flexibility has been demonstrated tremendous potential in the design of Zn-ion SCs, but achieving long cycling stability and high rate stability is still big challenges. Here, we proposed a facile laser writing approach to fabricate patterned Ti3C2Tx-based Zn-ion micro-supercapacitors (MSCs), followed by the in-situ anneal treatment of the assembled MSCs to improve the long-term stability, which exhibits 80% of the capacitance retention even after 50,000 charge/discharge cycles and superior rate stability. The influence of the cathode thickness on the electrochemical performance of the MSCs is also studied. When the thickness reaches 0.851 µm the maximum areal capacitance of 72.02 mF cm−2 at scan rate of 10 mV s−1, which is 1.77 times higher than that with a thickness of 0.329 µm (35.6 mF cm−2). Moreover, the fabricated Ti3C2Tx based Zn-ion MSCs have excellent flexibility, a digital timer can be driven by the single device even under bending state, a flexible LED displayer of “TiC” logo also can be easily lighted by the MSC arrays under twisting, crimping, and winding conditions, demonstrating the scalable fabrication and application of the fabricated MSCs in portable electronics.

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Supported gold catalysts have drawn worldwide interest due to the novel properties and potential applications in industries. However, the origin of the catalytic activity in gold nanoparticles is still not well understood. In this study, time-of-flight secondary ion mass spectroscopy (TOF-SIMS) has been applied to investigate the nature of gold in Au (1.3 wt %)/gamma-Al2O3 and Au (2.8 wt %)/TiO2 catalysts prepared by the deposition-precipitation method. The SIMS spectrum of the supported gold catalysts presented AuO-, AuO2-, and AuOH- ion clusters. These measurements show direct evidence for oxidized gold on supported gold catalysts and may be helpful to gaining better understanding of the origin of the catalytic activity.

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The release of the water-soluble drug Captopril is controlled by tailoring the surface properties of mesoporous silica via stepwise silylation. The degree of silylation is manipulated by adjusting the initial concentration of silylanizing reagent (trimethylchlorosilane, TMCS). The silylanized and drug-loaded samples are characterized by powder X-ray diffraction, Fourier transform IR spectroscopy, N2 adsorption and desorption, 29Si cross-polarization magic angle spinning NMR spectroscopy, and transmission electron microscopy. The drug-loading amount is correlated to the Brunauer-Emmett-Teller surface area and surface hydrophilicity/hydrophobicity of the mesoporous silica material, while drug release profiles can be controlled by tailoring the surface properties and pore size.