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The resistivity scaling of copper (Cu) interconnects with decreasing dimensions remains a major challenge in the downscaling of integrated circuits. Molybdenum phosphide (MoP) is a triple-point topological semimetal (TSM) with low resistivity and high carrier density. With the presence of topologically protected surface states that should be defect-tolerant and electron backscatter forbidden, MoP nanowires have shown promising resistivity values compared to Cu interconnects at the nanometer scale. In this work, using template-assisted chemical vapor conversion and standard fabrication techniques that are industry-adoptable, we report the fabrication of porous but highly crystalline MoP narrow lines with controlled sizes and dimensions. We examine the influence of porosity, thickness, and cross-section area on the resistivity values of the fabricated MoP lines to further test the feasibility of MoP for interconnect applications. Our work presents a facile approach to synthesizing TSM nanowires with different dimensions and cross sections, enabling experimental investigations of their predicted unconventional resistivity scaling behavior. Finally, our results provide insight into the effects of porosity on the resistivity of these materials on the nanometer scale. 

Energy production and storage is one of the foremost challenges of the 21st century. Rising energy demands coupled with increasing materials scarcity have motivated the search for new materials for energy technology development. Nanomaterials are an excellent class of materials to drive this innovation due to their emergent properties at the nanoscale. In recent years, two dimensional (2D) layered materials have shown promise in a variety of energy related applications due to van der Waals interlayer bonding, large surface area, and the ability to engineer material properties through heterostructure formation. Despite notable results, their development has largely followed a guess and check approach. To realize the full potential of 2D materials, more efforts must be made towards achieving a mechanistic understanding of the processes that make these 2D systems promising. In this perspective, we bring attention to a series of techniques used to probe fundamental energy related processes in 2D materials, focusing on electrochemical catalysis and energy storage. We highlight studies that have advanced development due to mechanistic insights they uncovered. In doing so, we hope to provide a pathway for advancing our mechanistic understanding of 2D energy materials for further research. 

Intercalation of alkali metals is widely studied to introduce a structural phase transition from 2H to 1T′ in 2D group VI transition metal dichalcogenides (TMDCs). This highly efficient phase transition method has enabled an access to a library of phases with novel physical and chemical properties attractive for functional devices and electrochemical catalysis. However, despite numerous studies that have predicted that charge doping mainly contributes to the structural phase transition in the intercalation process, a mechanistic understanding of the phase transition at the atomic level has not been fully revealed. Furthermore, the coupled effects of strain and other intrinsic or extrinsic factors on the intercalation‐induced phase transition have not been quantitatively determined. Herein, the progress of the intercalation‐induced phase transition is briefly overviewed and the knowledge gaps in the current understanding of phase transition and intercalation in 2D TMDCs are highlighted. To fully gain the microscopic picture of the intercalation‐induced phase transition, in situ multimodal probes to monitor the real‐time structure−property relationship during intercalation are suggested. The proposed research directions further direct material scientists to efficiently engineer phase transition pathways in 2D materials to explore novel functional phases. 

Abstract The development of next‐generation electrodes for metal‐ion batteries requires an understanding of intercalation dynamics in nanomaterials. Herein, it is shown that microscale mechanical strain significantly affects the formation of ordered lithium phases in graphene. In situ Raman spectroscopy of graphene microflakes mechanically constrained at the edge during lithium intercalation reveals a thickness‐dependent increase of up to 1.26 V in the electrochemical potential that induces lithium staging. While the induced mechanical strain energy increases with graphene thickness to the fourth power, its magnitude is small compared to the observed increase in electrochemical energy. It is hypothesized that the mechanical strain energy increases a nucleation barrier for lithium staging, greatly delaying the formation of ordered lithium phases. These results indicate that electrode assembly may critically impact lithium staging dynamics. The present work demonstrates strain engineering in two dimensional (2D) nanomaterials as an effective approach to manipulate phase transitions and chemical reactivity.