All-solid-state high-performance asymmetric supercapacitors (ASCs) are fabricated using γ-MnS as positive electrode and porous eggplant derived activated carbon (EDAC) as negative electrode with saturated potassium hydroxide agar gel as the solid electrolyte. The laminar wurtzite nanostructure of γ-MnS facilitates the insertion of hydroxyl ions into the interlayer space, and the manganese sulfide nanowire offers electronic transportation channels. The size-uniform porous nanostructure of EDAC provides a continuous electron pathway as well as facilitates short ionic transportation pathways. Due to these special nanostructures of both the MnS and the EDAC, they exhibited a specific capacitance of 573.9 and 396 F g−1 at 0.5 A g−1, respectively. The optimized MnS//EDAC asymmetric supercapacitor shows a superior performance with specific capacitance of 110.4 F g−1 and 89.87% capacitance retention after 5000 cycles, a high energy density of 37.6 Wh kg−1 at a power density of 181.2 W kg−1 and remains 24.9 Wh kg−1 even at 5976 W kg−1. Impressively, such two assembled all-solid-state cells in series can light up a red LED indicator for 15 minutes after fully charged. These impressive results make these pollution-free materials promising for practical applications in solid aqueous electrolyte-based ASCs.

Single-atom catalysts (SACs) have attracted much attention due to their outstanding catalytic performance in heterogeneous catalysis. Here, we report a template sacrificial method to fabricate an atomically dispersed Co catalyst; three kinds of silica templates with different microstructures (MCM-41, SBA-15, and FDU-12) were employed and the effect of pore structure of the templates on the dispersity of Co was investigated. The catalysts fabricated with different templates presented different Co dispersities, leading to distinguishing catalytic performance. The optimized Co 1 @NC-(SBA) catalyst with atomically dispersed Co displayed outstanding catalytic activity for the hydrodeoxygenation (HDO) of lignin-derived species as well as the hydrogenation of various nitroaromatics. The reaction mechanism of the HDO of vanillin was investigated by using density functional theory calculations as well.

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To construct a suitable three-dimensional structure for ionic transport on the surface of the active materials for a supercapacitor, porous hollow nickel cobalt sulfides are successfully synthesized via a facile and efficient cation-exchange reaction in a hydrothermal process involving the Kirkendall effect with γ-MnS nanorods as a sacrificial template. The formation mechanism of the hollow nickel cobalt sulfides is carefully illustrated via the tuning reaction time and reaction temperature during the cation-exchange process. Due to the ingenious porous hollow structure that offers a high surface area for electrochemical reaction and suitable paths for ionic transport, porous hollow nickel cobalt sulfide electrodes exhibit high electrochemical performance. The Ni(1.77)Co(1.23)S4 electrode delivers a high specific capacity of 224.5 mAh g(-1) at a current density of 0.25 A g(-1) and a high capacity retention of 87.0% at 10 A g(-1). An all-solid-state asymmetric supercapacitor, assembled with a Ni(1.77)Co(1.23)S4 electrode as the positive electrode and a homemade activated carbon electrode as the negative electrode (denoted as NCS//HMC), exhibits a high energy density of 42.7 Wh kg(-1) at a power density of 190.8 W kg(-1) and even 29.4 Wh kg(-1) at 3.6 kW kg(-1). The fully charged as-prepared asymmetric supercapacitor can light up a light emitting diode (LED) indicator for more than 1 h, indicating promising practical applications of the hollow nickel cobalt sulfides and the NCS//HMC asymmetric supercapacitor.

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