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 H2 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 H2 and carbon yields of polyethylene conversion reached 29.8 mmol/gplas 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.