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Electrodepositing manganese oxide into graphene hydrogel provides a facile and effective way to make full use of structural features of the hydrogel and capacity advantage of manganese oxide. The electrodeposition conditions play a key role in the deposition of manganese oxide, but little is known about their effect on electrochemical properties of the hybrid electrodes. Here, we systematically clarify the influences of deposition parameters (including current density, deposition time, Mn2+ concentration and bath temperature) on the capacitive performance (including apparent capacitance, specific capacitance, rate capability, cycling stability and charge storage mechanism) of manganese oxide/graphene oxide hydrogel hybrid electrodes. Under the proper preparation conditions, the highest specific capacitance of 453.7 F g−1 is obtained, and 92.4% capacitance retention (419.2 F g−1) is maintained after 5000 charge/discharge cycles, indicating excellent charge storage capability and cycling stability. Electrodeposition conditions play a decisive role in the capacitive performance of the manganese oxide/graphene oxide hydrogel electrodes. Image 1 [ABSTRACT FROM AUTHOR]

Electrodepositing manganese oxide in a three-dimensional graphene architecture has barely been explored, and therefore an exploratory but systematic investigation was conducted. A series of manganese oxide/graphene hydrogel electrodes were prepared by galvanostatic technique. The effects of electrodeposition condition, including current density, deposition time, Mn2+concentration and bath temperature, on the morphology and capacitive performance of the deposits were investigated. Nucleation and growth processes of the deposited manganese oxide were then deduced. An optimal capacitance of 452.5 F g−1 was got. This study could provide insight into the crystallization mechanism for electrochemical preparation of MnO x /graphene electrode for advanced energy storage/conversion devices. • Nucleation and growth processes of manganese oxide in a porous graphene monolith. • Effect of deposition conditions on electrocrystallization process. • Improved capacitive performance and flexible application. [ABSTRACT FROM AUTHOR]

• Both metallic Ag and Ag oxide exist in the coating. • A nano-sized Ag-rich layer exists at the substrate/coating interface. • PEO affects corrosion morphology and susceptibility of Mg-Ag alloy. • A sustained Ag+ release is achieved after PEO of Mg-Ag alloy. The application of biodegradable Mg alloys as implanted devices has been hindered by their low corrosion resistance and potential risk associated with microbial infection. In the present work, a rolled Mg-Ag alloy was studied, which was subjected to plasma electrolytic oxidation (PEO) to achieve a favoured balance between corrosion resistance and antimicrobial capability. The Ag distribution, corrosion resistance and Ag ionic release behaviour have been examined in details. It is revealed that PEO process leads to both incorporated Ag+ and Ag-rich nanoparticles in forms of metallic Ag and Ag oxide across the coating. In addition, a nano-sized Ag-enriched layer also exists at the substrate/coating interface. The microstructural modification associated with PEO process results in an increased corrosion resistance and a sustained Ag ionic release, indicating that it is a promising surface modification technique for antibacterial Mg-Ag alloy. [Display omitted] [ABSTRACT FROM AUTHOR]