Recent Advancements in the Fabrication of Functional Nanoporous Materials and Their Biomedical Applications

Abstract

Functional nanoporous materials are categorized as an important class of nanostructured materials because of their tunable porosity and pore geometry (size, shape, and distribution) and their unique chemical and physical properties as compared with other nanostructures and bulk counterparts. Progress in developing a broad spectrum of nanoporous materials has accelerated their use for extensive applications in catalysis, sensing, separation, and environmental, energy, and biomedical areas. The purpose of this review is to provide recent advances in synthesis strategies for designing ordered or hierarchical nanoporous materials of tunable porosity and complex architectures. Furthermore, we briefly highlight working principles, potential pitfalls, experimental challenges, and limitations associated with nanoporous material fabrication strategies. Finally, we give a forward look at how digitally controlled additive manufacturing may overcome existing obstacles to guide the design and development of next-generation nanoporous materials with predefined properties for industrial manufacturing and applications.

Keywords: additive manufacturing; dealloying; hierarchical nanoporous; nanoporosity; nanoporous materials.

Figure 1

(a) Schematic illustration showing the fabrication of nanoporous Au thin film by selective chemical dealloying of Au-Ag film in acidic medium (adapted from [56], Copyright 2015, American Chemical Society); (b) schematic depicting the fabrication of 3D bimodal nanoporous amorphous carbon by sequential chemical dealloying (adapted from [57], Copyright 2021, American Chemical Society).

Figure 2

(a) Schematic illustration showing liquid metal dealloying working principle (adapted from [38], Copyright 2021, Elsevier); (b) scanning electron microscopy (SEM) image of nanoporous TaTi after the removal of Cu from the TiTa-Cu composite (adapted from [76], Copyright 2020, Elsevier); (c) scheme displays the principle of vapor phase dealloying (adapted from [77], Copyright 2019, Elsevier).

Figure 3

(a) Schematic illustration displaying the formation of nanoporous carbon in different morphologies depending on the ratio of surfactant to trimethylbenzene (TMB) in the soft micellar structure (adapted from [93], Copyright 2019, American Chemical Society); (b) fabrication of ordered nanoporous materials ITO using silica colloidal crystals as a hard template (adapted from [94], Copyright 2015, American Chemical Society).

Figure 4

The fabrication of nanoporous materials of tunable porosity by 3D printing and chemical dealloying: (a,b) Digitally controlled macroporous 3D structures made from mixed Cu and Mn powder and polymer binder by direct ink writing; (c) thermal sintering at high temperature (1293 K) for 15 h to remove polymers and form Cu-Mn alloy; (d) nanoporous Cu fabrication by chemical dealloying in acidic environment to selectively remove Mn; (e–g) optical images of as-printed sintered and dealloyed sample. The scale bar in images (e–g): 10 mm. SEM images showing pore evolution after (h) 3D printing; (I,k) thermal sintering; and ( j–m) dealloying. The scale bar in (h–j) and (k–l) are 100 µm and 20 µm. The scale bar in (m) is 400 nm. Adapted from [120], Copyright 2020, Elsevier.

Figure 5

(a) The working principle of nanoporous fabrication using focused ion beam milling and melting process (adapted from [127], Copyright 2018 Royal Society of Chemistry); (b) schematic illustration displaying the fabrication of bimodal nanoporous Cu by a combined strategy involving laser processing and chemical dealloying (adapted from [129], Copyright 2022, Elsevier).