Tailoring Porosity in Copper-Based Multinary Sulfide Nanostructures for Energy, Biomedical, Catalytic, and Sensing Applications

Copper-based multinary sulfides (CMSs) have been the subject of intense research over the past decade due to the numerous outstanding properties that emerge when they are synthesized on the nanoscale. CMS compounds (e.g., CuInS2, Cu2SnS3, Cu12Sb4S13, and Cu2ZnSnS4) are best known for their immense potential in energy-related disciplines. Through nanoscale engineering, new and exciting opportunities have opened up for these materials to be used in a wider range of applications. This review accords particular attention to nanostructured CMS materials with porous morphological features to be used in energy, biomedical, catalytic, and sensing applications owing to their large, tunable, and accessible surface area. Although the construction of porous nanostructures of metals and binary materials has already been well established, tailoring porosity in multinary materials like CMSs remains a big challenge due to their multiple elemental components. Herein, we provide useful discussions on the different modes of pore formation that are fundamental to the construction of CMS nanostructures with tailor-made porosity. These pore-forming strategies are classified into three types: (1) Kirkendall effect-induced hollowing, (2) aggregation-based pore formation, and (3) template-assisted pore engineering. The ability to craft porous features in CMS nanomaterials has proven to be beneficial in advancing their properties and expanding their application domains, and thus, future efforts should be devoted to furthering our understanding of the various pore formation mechanisms as this could lead to the construction of more sophisticated porous CMS architectures with optimal performance for desired applications. We anticipate that the design concepts discussed here can be extended to other emerging classes of multinary materials.