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We report a greener, effortless, and scalable approach involving the synthesis of a self-grown nanomaterial on a flexible conductive substrate along with the synthesis of activated carbon derived from biomass waste. Contrary to the popular idea of using a variety of additives for the synthesis of nanomaterials, such as surface-activating agents, 3d metal-oxide nanoplates were synthesized on a highly hydrophobic carbon cloth substrate using no foreign elements except the metal precursors. The activated carbon was derived from biomass waste in that it was synthesized using withered cherry flower petals. The two as-synthesized materials were combined to fabricate an asymmetric supercapacitor, the design of which is presented as a greener and sustainable way to obtain an alternative energy storage unit. The three-dimensional nanoplate architecture from the positive electrode combined with the densely populated meso-/microporous structures of the negative electrode delivered an energy density of 106.3 μWh cm–2 for a power density of 657 μW cm–2, which is maintained at 57.5 μWh cm–2 even at a high power density of 5283.4 μW cm–2. Furthermore, a highly stable rate performance was achieved with high capacity retention even after charging–discharging for over 6000 cycles. The fabricated device exhibits highly satisfactory results in practice and hence presents itself as a highly capable candidate for a green energy solution.

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The removal of NO x over a Ag/γ-Al 2 O 3 catalyst coupled with gliding arc plasma at low temperatures is demonstrated. Specifically, n-heptane (the reducing agent) was pretreated by exposure to gliding arc plasma (the outlet gas temperature of 73.4 °C) before injecting into the simulated diesel exhaust gas and passing it through the catalyst zone. As a result of the plasma treatment, the feed gas consisted of oxygenated hydrocarbons (OHCs), which serve as reducing agents, instead of only n-heptane without plasma treatment. Consequently, the NO x removal efficiency increased substantially by approximately 10% at temperatures of [165−225 °C] owing to the presence of the OHCs. The dependence of the NO x removal efficiency on typical reducing agents was examined; these results agreed with our hypothesis that aldehyde derivatives were more effective than the parent compound (n-heptane) for NO x removal at low temperatures. However, enhancement of the NO x removal efficiency after plasma pretreatment was not observed at high plasma discharge power. This is because NO x is formed from the air and a significant amount of n-heptane is completely oxidized to CO 2 when the gliding arc plasma is operated at high power. Besides, the plasma treatment of n-heptane did not improve the NO x removal under high operating temperature conditions at which the catalyst itself exhibits high catalytic activity. This led us to surmise that boosting the effectiveness of the OHCs generated during plasma pretreatment would require the ratio of the exhaust gas flow rate to the reducing agent flow rate to be high, which is challenging to realize in laboratory-scale experiments. This method would lower the energy consumption of the plasma stage.