Bulk Nanostructured Materials Based on Two-Dimensional Building Blocks: A Roadmap.

The family of two-dimensional (2D) materials, in particular MXenes, can now be greatly expanded based on a new "double metal" strategy as reported by Anasori, Xie, and Beidaghi et al. in this issue of ACS Nano. Now that a diverse array of well-defined nanoscale building blocks, especially the 2D systems, has become available, we are better prepared to think about scaling up nanomaterials in the broader context of materials science and engineering. In this Perspective, we construct a roadmap for assembling nanoscale building blocks into bulk nanostructured materials, and define some of the critical challenges and goals. Two-dimensional sheets are uniquely well-suited in this roadmap for constructing dense, bulk-sized samples with scalable material performance or interesting emergent properties.