Construction of heterostructured silver nanoparticles/silver nanowires@hydrophilic carbon cloth fibers composites for dual-functional microwave absorption and antibacterial applications

Abstract

Advancing multifunctionality in microwave absorbing materials through strategic component selection and architectural tailoring is an emerging research focus. In this work, novel heterostructured composite-silver nanoparticles and silver nanowires anchored on hydrophilic carbon cloth fibers (AgNPs/AgNWs@HCCF) were synthesized via a polyol process coupled with impregnation. The flexible, three-dimensional HCCF scaffold served as a support matrix for the AgNPs and AgNWs, which are known for their outstanding dielectric properties and antibacterial capabilities. By forming heterojunctions, these components were integrated into the carbon cloth framework, enabling simultaneous microwave absorption and antimicrobial activity. The heterojunction interfaces contributed to enhanced electromagnetic attenuation by tuning the balance between conduction and polarization losses and thereby improving impedance matching. Notably, sample S2 achieved a peak reflection loss of −53.19 dB at a thickness of 2.86 mm and offered a broad effective absorption bandwidth of 5.36 GHz at 3.50 mm. In addition, the maximum radar cross-sectional reduction reached 35.21 dB·m2 at 0°. The antibacterial rates against Escherichia coli and Staphylococcus aureus were 99.40% and 99.93%, respectively.

1. Introduction

With the rapid advancement of electromagnetic technology, high-power electromagnetic devices have been extensively integrated into both industrial processes and daily life. However, excessive electromagnetic wave radiation presents significant risks to the functionality of precision instruments and to human health [1–3]. Therefore, the development of novel microwave absorbing materials (MAMs) for effective radiation mitigation has become increasingly critical [4–5].

In recent years, the application environments for MAMs have grown more complex. These materials are now employed in diverse settings, such as medical equipment, military combat zones, and personal protective gear, and often require performance under challenging conditions, including high humidity, microwave-infrared compatible stealth, flexibility for wearable technologies, and exposure to open wounds [6–8]. However, the surfaces of traditional MAMs with a single microwave absorption (MA) function are prone to becoming breeding grounds for gram-negative bacteria (G−) and gram-positive bacteria (G+), thereby increasing the risk of human infections such as pneumonia and urinary tract infections [9–11]. Escherichia coli (E. coli, a typical G− bacterium) and Staphylococcus aureus (S. aureus, a typical G+ bacterium) are widely recognized as standard model strains for antibacterial performance evaluation. Their core advantages include the following: first, a high degree of overlap with all scenarios of human production and daily life, resulting in a high frequency of environmental exposure; second, strong survival ability in natural environments, making them prone to persistent pollution; third, representative biological characteristics that can cover the core physiological and metabolic features of the vast majority of pathogenic bacteria [12–14]. Therefore, there is an urgent demand to develop MAMs that integrate both MA and antibacterial (against E. coli and S. aureus) functionalities.

Owing to their lightweight nature, low density, and high conductivity, among various candidate materials for MAMs, hydrophilic carbon cloth fibers (HCCF) have become among the most promising options [15–16]. Wang et al. highlighted the effectiveness of fibrous frameworks as foundational materials for developing flexible, wearable technologies, and multifunctional MAMs [17]. In addition, Qin and his co-workers engineered a multifunctional composite composed of polypyrrole, nickel, reduced graphene oxide, and carbon nanofibers through electrospinning. This material achieved a remarkable minimum reflection loss (RLmin) of −46.15 dB and a broad effective absorption bandwidth (EAB) of 8.63 GHz, successfully merging microwave attenuation with infrared stealth capabilities [18]. In metal material systems, the compositing of noble metals (e.g., Au, Ag, and Pt) with matrices enables the formation of many heterointerfaces, thereby effectively enhancing interfacial and dipolar polarization effects [19