Samples used for EM parameter measurement were prepared by mixing the TiO2-Ti3C2Tx and Fe3O4@TiO2-Ti3C2Tx powders with paraffin with a mass content of 70%. In a typical composite preparation, powders and paraffin were well mixed at 80±2 ºC mechanically to avoid aggregation. After 5 min, the viscous mixtures were casted on the respective Teflon molds. Conducting Aluminum tape was pasted at the bottom of the fabricated structure as a perfect electric conductor (PEC). Schematically, fabrication process of both the meta structure i.e., pyramidal and multi-layered pyramidal structure was shown in Figure S1 and Figure S2 respectively. Reflection loss (S-parameters) were measured inside anechoic chamber by using an Agilent PNA N523A vector network analyzer using two horn antenna. In the measurement set-up, a pair of horn antenna was used as a transmitter to send off the electromagnetic wave onto the composite sample, whereas the other antenna was used to receive the reflection from the sample. All the horn antennas were connected to the vector network analyzer (VNA) during the entire measurements. The entire broadband absorption measurement technique was shown schematically in Figure S3. 

MXene, the new family of 2D materials having numerous nanoscale layers, is being considered as a novel microwave absorption material. However, MXene/functionalized MXene loaded polymer nanocomposites exhibit narrow reflection loss (RL) bandwidth (RL ≤ -10 dB). In order to enhance the microwave absorption bandwidth of MXene hybrid-matrix materials, for the first time, macroscopic design approach is carried out for TiO2-Ti3C2Tx MXene and Fe3O4@TiO2-Ti3C2Tx MXene hybrids through simulation. The simulated results indicate that use of pyramidal meta structure of MXene can significantly tune the RL bandwidth. For optimized MXene hybrid-matrix materials pyramid pattern, the bandwidth enhances to 3-18 GHz. Experimental RL value well matched with the simulated RL. On the other hand, for optimized Fe3O4@TiO2-Ti3C2Tx hybrid exhibits two specific absorption bandwidths viz. 3-18 GHz (minimum RL value - 47 dB). Compared to other 2D nanocomposites such as graphene or Fe3O4-graphene, MXene hybrid-matrix materials shows better microwave absorption bandwidth in macroscopic pattern.