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The rapid miniaturization of portable and wearable electronics has gained increasing demand for flexible and high-performance microscale energy storage devices such as micro-supercapacitors (MSCs) that provide flexibility and portability. Volumetric capacitance is the most significant metric for miniaturized capacitive energy storage units due to the limitations in device volume and active surface area. Herein, we have used an ultrathin (3.5 nm) two-dimensional (2D) Co(OH)2 nanosheet (NS) as an electrode material to fabricate a flexible, solid-state MSC on micropatterned laser-scribed graphene (LSG). On account of the combination of ultrathin morphology, in-plane geometry of interdigitated microelectrodes, and highly conductive and robust interaction of ultrathin Co(OH)2 NS and LSG, the Co(OH)2 NS-LSG-based micro-supercapacitor (CN-LSG MSC) exhibits high rate-capability and delivers a superior volumetric capacitance of 258 F cm−3 at 13 A cm−3 current density. Moreover, the CN-LSG MSC device achieved an excellent energy density of 22 mW h cm−3 at a power density of 6.8 W cm−3 with a remarkable cyclic stability of 96.4% even after 20 000 charge–discharge cycles. The fabricated CN-LSG MSC exhibits unaffected mechanical flexibility under different bending deformations. Additionally, we have demonstrated the possibility of integrating a CN-LSG MSC by connecting it in series and parallel configurations, which amplifies the operating voltage and output current, respectively. Therefore, the present research work opens a new avenue for the simple and scalable manufacture of ultrathin film-based MSCs promising for various lightweight, miniaturized, flexible, and wearable electronics. [ABSTRACT FROM AUTHOR]

Ammonia, which is one of the most important chemicals for the synthesis of dyes, pharmaceuticals, and fertilizers, is produced by the reaction of molecular hydrogen with nitrogen, over an iron-based catalyst at 400-500 °C under pressure of over 100 bar. Decreasing the operating temperature and pressure of this highly energy-intensive process, developed by Haber and Bosch over 100 years ago, would decrease energy consumption in the world. In this work, we used two-dimensional Mo 2 CT x MXene as a support for a cobalt-based catalyst. The MXene functionalized by Co showed catalytic activity for ammonia synthesis from H 2 and N 2 at temperatures as low as 250 °C, without any pretreatment. The developed catalyst was highly active for ammonia synthesis, demonstrating a high rate of up to 9500 μmol g -1 active phase h -1 at 400 °C under ambient pressure in steady-state conditions, and did not suffer from any deactivation after 15 days of reaction. The apparent activation energy ( E a ) was found to be in the range of 68-74 kJ mol -1 , which is in line with values reported for highly active catalysts. This improved catalyst may decrease the energy consumption in the synthesis of ammonia and its derivatives, as well as facilitate the use of ammonia as a hydrogen carrier for renewable energy storage.