Hydrogen peroxide sensor based on in situ grown Pt nanoparticles from waste screen-printed electrodes

Screen printing technology is widely used for the fabrication of low-cost disposable electrodes. However, this generates solid wastes that contain precious metals like platinum, which is highly polluting and quite valuable for different industries. Therefore, it is necessary to process spent platinum-containing materials to meet future demand and to protect resources. This work presents, for the first time, a procedure to recycle platinum from waste screen-printed electrodes using aqua regia as the leaching solution. Platinum from this solution was electrodeposited as nanoparticles onto the surface of screen-printed carbon electrodes (PtNPs@SPCEs) directly. PtNPs were characterized by SEM and X-ray diffraction analyses. PtNPs@SPCEs were applied as a hydrogen peroxide sensor, with similar results to those obtained with PtNPs from standard hexachloroplatinic acid solutions. With very small quantities of deposited platinum (μg), the reached sensitivity of the PtNPs@SPCEs was 687.3 nA cm−2 μM−1 and the limit of detection was 1.9 μM (based on a S/N ratio = 3). The sensitivity towards H2O2 was improved ∼360 times compared to commercial SPCEs, and ∼7 times compared to commercial screen-printed platinum electrodes.