3D meso/macroporous carbon from MgO-templated pyrolysis of waste plastic as an efficient electrode for supercapacitors.

Converting waste plastic into valuable carbon materials as the electrode for supercapacitors represents a sustainable way to deal with the severe waste plastic-related environmental issues. However, ideal carbon materials for supercapacitors require not only a large specific surface area but also abundant meso/macropores, which is still challenging for conventional synthesis methods. Herein, MgO-templated pyrolysis with chemical activation was demonstrated as an effective approach to convert waste polyethylene terephthalate (PET) plastic bottles into 3D meso/macroporous carbon (MMPC) with both large total surface area (1863.55 m2/g) and meso/macropore surface area (1478.46 m2/g). Furthermore, it exhibited a high capacitance of 191.4 F/g and an excellent rate capability (86.3% retention from 0.5 to 10 A/g) for supercapacitor. This work provides not only a facile approach to synthesize 3D meso/macroporous carbon materials but also a sustainable way to mitigate plastic-derived pollution.

Turning dead leaves into an active multifunctional material as evaporator, photocatalyst, and bioplastic.

Large numbers of leaves fall on the earth each autumn. The current treatments of dead leaves mainly involve completely destroying the biocomponents, which causes considerable energy consumption and environmental issues. It remains a challenge to convert waste leaves into useful materials without breaking down their biocomponents. Here, we turn red maple dead leaves into an active three-component multifunctional material by exploiting the role of whewellite biomineral for binding lignin and cellulose. Owing to its intense optical absorption spanning the full solar spectrum and the heterogeneous architecture for effective charge separation, films of this material show high performance in solar water evaporation, photocatalytic hydrogen production, and photocatalytic degradation of antibiotics. Furthermore, it also acts as a bioplastic with high mechanical strength, high-temperature tolerance, and biodegradable features. These findings pave the way for the efficient utilization of waste biomass and innovations of advanced materials.

Metal-catalyst-free carbohydrazide fuel cells with three-dimensional graphene anodes.

As a potential solution to concerns on sustainable energy, the wide spread commercialization of fuel cell has long been hindered by limited reserves and relatively high costs of metal catalysts. 3D graphene, a carbon-only catalyst prepared by reduction of carbon monoxide with lithium oxide, is found to electrochemically catalyze carbohydrazide oxidation reaction efficiently. A prototype of a completely metal-catalyst-free anion exchange membrane fuel cell (AEMFC) with a 3D graphene anode catalyst and an N-doped CNT (N-CNT) cathode catalyst generate a peak power density of 24.9 mW cm(-2) . The average number of electrons electrochemically extracted from one carbohydrazide molecule is 4.9, indicating the existence of CN bond activation, which is a key factor contributing to high fuel utilization efficiency.