Efficient transformation of plastic wastes to H2 and electromagnetic nanocarbon absorbents over molecular-level engineered 3D NiCo/MnO.

[Display omitted] • Bimetallic Co-Ni catalysts were firstly developed by a molecular-level engineering strategy. • The superior performance of bimetallic catalysts is unprecedentedly pinpointed via DFT calculations. • The specific yields of carbon nanocomposites and H 2 are outstanding compared to the reported work. • The carbon nanocomposites exhibited excellent electromagnetic absorption performance. The advancement in the pyrolysis-catalysis conversion of waste plastics is currently limited by three problematic issues, namely lack of efficient catalysts, ambiguous catalytic mechanism, and identification of a dedicated application of carbon nanocomposites. Herein, advanced bimetallic NiCo/MnO catalysts were developed via a molecular- and macroscale-level engineering strategy. The best conversion performance among all batches was achieved for a Co:Ni molar ratio of 1:1. When the plastic-to-catalyst ratio is 10.7:1, the H 2 and carbon yields of polyethylene conversion reached 29.8 mmol/g plas and 42.2 wt%, respectively. Density functional theory simulations rationalized the activity of NiCo/MnO catalysts in the dehydrogenation of hydrocarbons. The resulting carbon nanocomposites demonstrated excellent electromagnetic absorption performance with an effective absorption bandwidth of the representative carbon nanocomposites/wax composite of 5.12 GHz and a minimal reflection loss lower than −45 dB. This work provides novel insights for developing advanced catalysts for the pyrolysis-catalysis conversion of waste plastics. [ABSTRACT FROM AUTHOR]