Metal cyanamides represent a category of inorganic functional materials with superior activity and stability. However, their potential application in plastic recycling remains unexplored. This study mainly focused on the utilization of zinc cyanamide (ZnNCN) as a poly(ethylene terephthalate) (PET) glycolysis catalyst. The PET glycolysis process is demonstrated to be promoted by a synergistic catalysis effect. Under optimal conditions, 100% PET conversion and 92.3% bis(2-hydroxyethyl) terephthalate (BHET) yield were achieved. Furthermore, successful depolymerization toward various real commercial PET wastes and excellent recycling performance proved promising application prospects. DFT study and NMR characterization have revealed that the remarkable catalytic activity stems from the synergistic effect of the Lewis acid site and hydrogen bonds between ethylene glycol (EG) and the catalyst. This work provides valuable insight into the application of metal cyanamides, paving the way for the development of effective catalysts for PET recycling.
Carbon-based supercapacitors are prospective candidates for next-generation energy storage systems . However, there remains challenges in the development of high volumetric capacitance carbon electrodes. Herein, nitrogen-enriched lignin-derived porous carbons (NLSCs) were fabricated by co-pyrolysis of sodium lignosulfonate with zinc oxalate and melamine via an efficient nitrogen doping strategy. The in-situ generation of zinc cyanamide (ZnNCN) achieves a high nitrogen conversion rate of 13.5 %, much higher than that of ZnCl 2 activation (1.9 %), and endows the optimized NLSC-800 an extremely high nitrogen doping (14.47 at.%), abundant edged nitrogen species, and a high bulk density (1.26 g cm −3 ), contributing to substantially improved surface property and boosting pseudocapacitance . Consequently, the NLSC-800 supercapacitor electrode delivered a high gravimetric capacitance of 300 F g −1 and superior volumetric capacitance of 378 F cm −3 . More remarkably, the symmetric supercapacitor assembled by NLSC-800 performs an exceptional volumetric energy density of 5.1 Wh L −1 at 173.0 W L −1 . The capacitance retention rate is 97.6 % over 20,000 charge/discharge cycles at 2.0 A g −1 , exhibiting outstanding cycling stability. This strategy suggests a novel route for fabricating nitrogen-doped biomass-derived carbon for supercapacitors with balanced the gravimetric and volumetric capacitance.
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