## 4 Conclusions  
In conclusion, this study investigated the development and performance of carbonaceous shape-stabilized octadecane/MWCNTs composite materials, focusing on activated carbon, ceramic carbon foam, and expanded graphite as the support matrices. The findings highlight the potential of these composites for enhanced energy storage and electromagnetic interference (EMI) shielding applications. SEM analysis, supported by CT microtomography, revealed that CNTs are uniformly dispersed on both the AC and the EG matrices, with the AC surface being completely covered by CNTs. However, in the case of CCF, the macroporous structure likely encapsulates the CNTs/OD mixture within its depth, making them indistinguishable in SEM images. These observations highlight the varying interactions between CNTs and different carbon matrices, influenced by the inherent surface properties and porosity of each material. The leaching tests affirmed that all three carbon matrices--activated carbon, expanded graphite, and ceramic carbon foam--effectively stabilize octadecane, with or without MWCNTs. This stability indicates their suitability for applications that require dependable thermal energy storage while maintaining minimal environmental impact. Among the matrices without MWCNTs, the activated carbon composites showed the lowest \(\Delta\)H values and the most significant reduction from theoretical \(\Delta\)H values. Ceramic carbon foam displayed a smaller reduction in \(\Delta\)H values, while expanded graphitevalues remained close to theoretical expectations. The introduction of MWCNTs markedly enhanced the \(\Delta\)H values across all matrices, resulting in more efficient energy storage. In terms of EMI shielding, the primary mechanism observed was absorption, which was further enhanced by the incorporation of MWCNTs in the case of the AC and the EG samples. Notably, the EMI shielding effectiveness of the activated carbon samples was superior to that of the expanded graphite samples. On the other hand, in the case of the CCF samples, the EMI shielding effectiveness of the samples was not significantly enhanced, due to the low electrical conductivity of red mud. These findings open up new possibilities for advanced materials that can meet the rigorous demands of modern energy storage systems and EMI protection technologies. The following supporting information can be downloaded at: [[https://www.mdpi.com/article/10.3390/molecules29184363/s1](https://www.mdpi.com/article/10.3390/molecules29184363/s1)]([https://www.mdpi.com/article/10.3390/molecules29184363/s1](https://www.mdpi.com/article/10.3390/molecules29184363/s1)), Figure S1: Microtomography CT images of (a) AC, (b) C/OD and (c) AC/CNTs/OD. Figure S2: Microtomography CT images of (a) CCF, (b) CCF/OD and (c) CCF/CNTs/OD. Conceptualization, G.K. and M.A.K. ; methodology, G.K. and M.A.K. ; formal analysis, M.B., C.G., K.C.V., A.D., V.M.P., Z.V., A.N. and D.M. ; investigation, C.G., K.C.V., A.D., V.M.P., Z.V., A.N. and D.M. ; resources, A.S.P., G.K. and M.A.K. ; data curation, M.B., C.G., K.C.V., Z.V., G.K., A.S.P., D.M. and M.A.K. ; validation, M.B., A.D., V.M.P., A.N. and A.S.P. ; writing--original draft preparation, C.G., M.B., G.K. and M.A.K. ; writing--review and editing, M.B., G.K. and M.A.K. ; visualization, M.A.K. ; supervision, M.A.K. ; project administration, G.K. and M.A.K. ; funding acquisition, G.K. and M.A.K. All authors have read and agreed to the published version of the manuscript. This work was co-financed by the project \"Advanced Nanostructured Materials for Sustainable Growth: Green Energy Production/Storage, Energy Saving and Environmental Remediation\" (TAEDR-0535821), which is implemented under the action \"Flagship actions in interdisciplinary scientific fields with a special focus on the productive fabric\" (ID 16618), Greece 2.0--National Recovery and Resilience Fund--and funded by the European Union's NextGenerationEU. Not applicable. The data presented in this study are available upon request from the corresponding author.