Multi-scale designed Co Mn3–O4 spinels: Smart pre-catalysts towards high-efficiency pyrolysis-catalysis recycling of waste plastics

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

“…The main peak at binding energy (BE) (Co 2p3/2) = 780 eV can be characterized by the c ˗1 d x+1 L ˗1 configuration where c denotes the core hole and d x+1 L ˗1 the charge transfer from the ligand to the d-orbital. For the NixCo1-xMn2O4 samples, we have identified the main peak as a mixture of d 6 L ˗1 and d 7 L ˗1 and the satellite at 790 eV as d 6 L and at 786 eV as d 7 L due to the similar shape and interpretation as for Co3O4 [27] . Due to the small intensity of the satellites and the overlap with multiple effects, no quantitative analysis of the oxidation state is possible.…”

“…Due to the shape-inducing effects, these particles were shaped into flat 2D nanosheets [27] . In the third step, when the size in the 2D direction is large enough, new growth of another flake starts from the bottom of the initial flake, which finally leads to the formation of a 3D structure.…”

“…Carbon and H2 yields (CY and HY) have been the widely accepted factors for the evaluation of the conversion efficiency of waste plastics [2,3,27] . However, in the industrial application, CY and HY are not sufficient for understanding the overall conversion performance as a higher CY and HY can be easily achieved by employing a larger amount of catalysts (Table S2), which directly increases the upcycling costs and challenges in the purification of the CNTs.…”

“…The multi-scale engineering route (e.g., molecular-level engineering of the composition and nano/micro-level engineering of the structure) was proven to be a promising way for the precise controlling of advanced catalysts [27] . In our former work, multi-scale engineered CoxMn3-xO4 spinel derived Co/MnO catalysts exhibited outstanding performance with respect to the unprecedently high specific yield of carbon and hydrogen [27] . Notably, due to the excellent integrity of the CNTs and the absence of supporting phases, the produced CNCs exhibited a large aspect ratio and excellent electrochemical performance.…”

“…Meanwhile, the controllable morphology of spinels will promote the accessibility of active sites to reactants, which makes them a perspective for catalytic pyrolysis of PWs [32][33][34] . MnO as a catalyst promoter can not only enhance the catalytic performance but also prevent the catalyst from agglomeration [27,35] . Importantly, MnO as a semi-conductive phase can improve the impedance matching of the CNTs-like structure and establish a heterointerface (e.g., MnO-carbon) if it is introduced into the CNCs, which can enhance the electromagnetic absorption capability of the CNCs [36,37] .…”