In a recent article published in Scientific Reports, researchers introduced a novel composite material, combining laser-induced graphene (LIG) with silver nanoparticles (AgNPs), synthesized through an environmentally friendly method. The study evaluates the composite's electrochemical performance as a supercapacitor electrode and its antifungal properties against pathogenic Candida species.
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Background
LIG has a high surface area, porosity, and electrical conductivity, making it suitable for supercapacitor applications. The synthesis of LIG involves laser ablation of polyimide substrates, which transforms the material into a porous graphene structure. Adding silver nanoparticles enhances the electrical conductivity and introduces antimicrobial properties to the composite.
The silver nanoparticles were synthesized using a method involving the reduction of silver nitrate with plant extracts from Swietenia macrophylla bark. This approach provides a sustainable method for nanoparticle synthesis and ensures that the resulting material is non-toxic and environmentally friendly.
The Current Study
LIG was synthesized by ablating a polyimide substrate with a CO2 laser engraver, creating a porous graphene structure. The laser parameters were adjusted to ensure a uniform and consistent LIG surface.
For the synthesis of AgNPs, Swietenia macrophylla bark extract was used as a reducing agent. The bark was dried, powdered, mixed with deionized water, and stirred for 48 hours at 180 rpm and 32 °C. The mixture was centrifuged to obtain the supernatant, which was combined with a 2 mM AgNO3 solution in a 1:2 ratio and incubated for 48 hours to promote nanoparticle formation.
The LIG-AgNP composite was prepared using two methods: drop-coating and screen-printing. For drop-coating, the synthesized AgNPs were dispersed in ethanol and applied to the LIG surface, followed by drying at 80 °C. In the screen-printing method, commercial Ag ink was mixed with a solvent and printed onto the LIG using a mesh screen.
Electrochemical characterization included measuring sheet resistance and conductivity using a four-probe method. The electrochemical performance of the supercapacitors was evaluated through cyclic voltammetry (CV) and galvanostatic charge-discharge tests to determine specific capacitance and energy density. Antifungal activity against Candida species was assessed using inhibition assays, with effectiveness measured by the zone of inhibition compared to control samples.
Results and Discussion
The study showed that the LIG-AgNP composite had improved electrical conductivity compared to LIG alone. The drop-coated electrode (E1) had a sheet resistance of 37.10 Ω and a conductivity of 12.2 S cm-1, while the screen-printed electrode (E2) exhibited better performance with a sheet resistance of 28.25 Ω and a conductivity of 16.04 S cm-1.
In contrast, the commercially available Ag ink screen-printed electrode (E3) demonstrated a sheet resistance of 3.00 Ω and a high conductivity of 151.09 S cm-1. These results indicate that the method of AgNP application significantly affects the electrical properties of the composite.
The electrochemical performance of the supercapacitors was evaluated through specific capacitance and energy density measurements. The screen-printed composite showed a specific capacitance of 118 mF cm-² and an energy density of 2.42 mWh cm-², while the drop-coated composite had a lower specific capacitance of 38 mF cm-² and an energy density of 0.05 mWh cm-². These results indicate that the screen-printing method enhances both the electrical properties and overall performance of the supercapacitor.
The antifungal activity of the LIG-AgNP composites was also tested against Candida species. The screen-printed electrode effectively inhibited the growth of pathogenic fungi, demonstrating significant antifungal properties. This dual functionality—as an efficient energy storage device and an antimicrobial agent—underscores the potential of the composite for applications in flexible electronics and biomedical technologies.
Conclusion
This study developed an LIG-AgNP composite with enhanced electrical conductivity and antifungal properties. The environmentally friendly synthesis of AgNPs using plant extracts supports the sustainability of the material but also enhances its applicability in various fields.
The results show that the AgNP application method substantially impacts the composite's electrical performance, with screen-printing yielding better outcomes than drop-coating. Additionally, the demonstrated antifungal activity against Candida species suggests potential applications in healthcare.
The LIG-AgNP composite contributes to progress in sustainable energy storage solutions and antimicrobial materials, providing a basis for further research and practical applications in these areas.
Journal Reference
Prakash A., et al. (2024). Highly conducting Laser-Induced Graphene-Ag nanoparticle composite as an effective supercapacitor electrode with anti-fungal properties. Scientific Reports. DOI: 10.1038/s41598-024-79382-3, https://www.nature.com/articles/s41598-024-79382-3