3D-printed Metal Electrodes for Heavy Metals Detection by Anodic Stripping Voltammetry

Heavy metals, being one of the most toxic and hazardous pollutants in natural water, are of great public health concern. Much effort is still being devoted to the optimization of the electroanalytical methods and devices, particularly for the development of novel electrode materials in order to enhance selectivity and sensitivity for the analysis of heavy metals. The ability of 3D-printing to fabricate objects with unique structures and functions enables infinite possibilities for the creation of custom-made electrochemical devices. Here, stainless steel 3D-printed electrodes (3D-steel) have been tested for individual and simultaneous square wave anodic stripping analysis of Pb and Cd in aqueous solution. Electrodeposition methods have also been employed to modify the steel electrode surface by coating with a thin gold film (3D-Au) or a bismuth film (3D-Bi) to enhance the analytical performance. All 3D-printed electrodes (3D-steel, 3D-Au and 3D-Bi) have been tested against a conventionally employed glassy carbon electrode (GC) for comparison. The surface modified electrodes (3D-Au and 3D-Bi) outperformed the GC electrode demonstrating higher sensitivity over the studied concentration ranges of 50-300 and 50-500ppb for Pb and Cd, respectively. Owing to the bismuth property of binary alloys formation with heavy metals, 3D-Bi electrode displayed well-defined, reproducible signals with relatively low detection limits of 3.53 and 9.35ppb for Pb and Cd, respectively. The voltammetric behaviour of 3D-Bi electrode in simultaneous detection of Pb and Cd, as well as in individual detection of Pb in tap water was also monitored. Overall, 3D-printed electrodes exhibited promising qualities for further investigation on a more customizable electrode design.