Microstructure-Dependent Particulate Filtration using Multifunctional Metallic Nanowire Foams

TL;DR

This paper presents a multifunctional metallic nanowire foam filtration platform that is efficient, antimicrobial, and reusable, with microstructure-dependent performance for deep-submicron particle capture and potential applications in protective filtration.

Contribution

It introduces a novel nanowire foam design with microstructure control, demonstrating enhanced filtration efficiency and antimicrobial properties for advanced protective media.

Findings

Nanogranules increase surface area up to 20 m²/g but do not significantly improve capture efficiency.

Nanowire density and diameter significantly influence particle capture efficiency.

Cu foams achieve >99.9995% microbial inactivation within 30 seconds.

Abstract

The COVID-19 pandemic has shown the urgent need for the development of efficient, durable, reusable and recyclable filtration media for the deep-submicron size range. Here we demonstrate a multifunctional filtration platform using porous metallic nanowire foams that are efficient, robust, antimicrobial, and reusable, with the potential to further guard against multiple hazards. We have investigated the foam microstructures, detailing how the growth parameters influence the overall surface area and characteristic feature size, as well as the effects of the microstructures on the filtration performance. Nanogranules deposited on the nanowires during electrodeposition are found to greatly increase the surface area, up to 20 m$^{2}$/g. Surprisingly, in the high surface area regime, the overall surface area gained from the nanogranules has little correlation with the improvement in capture efficiency. However, nanowire density and diameter play a significant role in the capture efficiency of PM$_{0.3}$ particles, as do the surface roughness of the nanowire fibers and their characteristic feature sizes. Antimicrobial tests on the Cu foams show a >99.9995% inactivation efficiency after contacting the foams for 30 seconds. These results demonstrate promising directions to achieve a highly efficient multifunctional filtration platform with optimized microstructures.