Development of an ALD-Pt@SWCNT/Graphene 3D Nanohybrid Architecture for Hydrogen Sensing

A nanohybrid architecture composed of single-wall carbon nanotube films and graphene heterostructures (SWCNT/graphene) was developed as a three-dimensional (3D) electrode. Atomic layer deposition (ALD) was used for conformal coating of catalytic Pt nanoparticles on the 3D ALD-Pt@SWCNT/graphene nanohybrid architecture for further enhancement of H₂ sensing, taking advantage of the large sensing area and conformally coated nanostructures of the catalytic Pt. Remarkably, the H₂ response was found to be improved by 50% in the SWCNT/graphene nanohybrid, indicating that graphene provides a more efficient charge transport. The ALD-Pt further enhances the H₂ responsivity of the 3D ALD-Pt @SWCNT/graphene nanohybrids. By coating 10 cycles of ALD-Pt on the SWCNT/graphene nanohybrid, the H₂ response (2.77%) is approximately twice that (1.4%) of its counterpart without the ALD-Pt. By further optimizing the 3D ALD-Pt@SWCNT/graphene nanohybrids with respect to the ALD-Pt cycle numbers and SWCNT film thickness, a H₂ responsivity as high as 7.5% was achieved on the SWCNT/graphene nanohybrid sample with a 560 nm thick SWCNT film and 50 cycles of ALD-Pt.

Short Carbon Fiber Reinforced Polymers: Utilizing Lignin to Engineer Potentially Sustainable Resource-Based Biocomposites

Carbon fiber reinforced composites have exceptional potential to play a key role in the materials world of our future. However, their success undoubtedly depends on the extent they can contribute to advance a global sustainability objective. Utilizing polymers in these composites that can be potentially derived from biomasses would be certainly vital for next-generation manufacturing practices. Nevertheless, deep understanding and tailoring fiber-matrix interactions are crucial issues in order to design carbon fiber reinforced sustainable resource-based biocomposites. In this study, cellulose derivatives (cellulose propionate and cellulose acetate butyrate) are utilized as model polymer matrices that can be potentially fabricated from biomasses, and the mechanical properties of the prepared short carbon fiber reinforced composites are engineered by means of a functional biobased lignin coating on the fiber surface. Furthermore, polyamide 6 based composites are also prepared, the monomer of this polymer could be obtained using C6 sugars derived from lignocellulosic biomasses in the future (through 5-hydroxymethylfurfural). Lignin was successfully immobilized on the carbon fiber surface via an industrially scalable benign epoxidation reaction. The surface modification had a beneficial impact on the mechanical properties of cellulose propionate and polyamide 6 composites. Furthermore, our results also revealed that cellulose-based matrices are highly sensitive to the presence of rigid fiber segments that restrict polymer chain movements and facilitate stress development. It follows that the physicochemical properties of the cellulosic matrices (molecular weight, crystallinity), associated with polymer chain mobility, might need to be carefully considered when designing these composites. At the same time, polyamide 6 showed excellent ability to accommodate short carbon fibers without leading to a largely brittle material, in this case, a maximum tensile strength of ~136 MPa was obtained at 20 wt% fiber loading. These results were further contrasted with that of a petroleum-based polypropylene matrix exhibiting inferior mechanical properties. Our study clearly indicates that carbon fiber reinforced polymers derived and designed using biomass-derived resources can be promising green materials for a sustainable future.