Eco-friendly integration of gold nanoparticles into additive manufacturing filaments: advancing conductivity and electrochemical performance

Abstract

This work reports the inclusion of gold nanoparticles within conductive additive manufacturing filament for an improved electrochemical and electroanalytical performance. An eco-friendly synthesis was utilised, where graphite flakes are used as a natural reducing agent for the formation of gold nanoparticles. In this way, the graphite acts as both a reducing agent and contributes to the conductivity of the filament. The presence of gold nanoparticles on the surface of the graphite was confirmed through SEM, EDX, XRD and XPS analysis, after which the graphite was thermally mixed into recycled PLA along with carbon black and castor oil to create the conductive filament. Electrodes printed from this filament produced an enhanced electrochemical performance with a ΔE_p of 111 (±5) mV, a heterogeneous electron (charge) transfer rate constant, using hexaammineruthenium(III) chloride, of k⁰ of 2.04 (±0.08) × 10⁻³ cm s⁻¹, and the real electrochemical surface area, A_real of 0.53 (± 0.04) cm² upon the inclusion of gold nanoparticles. This filament also provided a significantly enhanced electroanalytical performance toward the proof-of-concept determination of lead(II), producing a linear range between 1–75 ppb (μg L⁻¹), with a sensitivity of 37 nA ppb⁻¹, an R² value of 0.98 and a limit of detection and limit of quantification of 0.89 ppb and 2.97 ppb, respectively. The electrodes were additionally successfully applied toward the determination of lead(II) within river water samples. This work demonstrates how advancements in the production of conductive additive manufacturing filaments can be achieved, paving the way for new research opportunities while adhering to eco-friendly practices.