Digital.CSIC. Repositorio Institucional del CSIC

oai:digital.csic.es:10261/337138

26 pages. -- Figure S1. Photo of the fluidic sensing system used in our study. -- Figure S2: Raman spectrum of GSH nanosheet. --Figure S3. Optimization of different supporting electrolytes and concentrations. -- Figure S4. Optimization of different volumes of GSH supernatant drop-casted on SPCEs and deposition potential. -- Table S1 The detailed data in optimization of different deposition potentials. Fgure S5. Optimization of flow time and flow rate. -- Figure S6. The individual HM ions detection. -- Figure S7. Cyclic voltammetry and electrochemical impedance spectroscopy of Bare and GSH-SPCE. -- Table S2. The detailed fitting results in electrochemical impedance spectroscopy. -- Figure S8. The comparison between individual measurements and simultaneous measurements on bare SPCE in our previous study. -- Figure S9. The absence of peak B in individual detection of 80 ppb Pb. -- Table S3. The summary of the obtained sensitivity (calibration slope), Y-intercept and R2 in all comparative experiments in this study. -- Table S4. The LODs of GSH-SPCE and bare SPCE towards Cd, Pb and Cu in the simultaneous detection. -- Figure S10. The data of sensing signals in repeatability study. -- Table S5. Summary of reusable times and repeatability in other studies using Bi-based electrodes and non-covalently functionalized graphene derivatives/composites. -- Table S6. The data of sensitivities in reproducibility study and Student´s T-test. -- Figure S11. The estimated concentration of GSH, GA and GO is characterized by UV-Vis. -- Table S7. Typical hard and soft acids and bases example. -- Figure S12. The detailed data in the interference study. -- Figure S13. The sensing performance of GSH-SPCE in spiked tap water. -- 23 Table S8 The investigation of the accuracy of GSH-SPCE in spiked tap water. -- Table S9. Comparison with other studies in the literature., Heavy metal pollutants are of great concern to environmental monitoring due to their potent toxicity. Electrochemical detection, one of the main techniques, is hindered by the mutual interferences of various heavy metal ions in practical use. In particular, the sensitivity of carbon electrodes to Cd2+ ions (one of the most toxic heavy metals) is often overshadowed by some heavy metals (e.g. Pb2+ and Cu2+). To mitigate interference, metallic particles/films (e.g. Hg, Au, Bi, and Sn) typically need to be embedded in the carbon electrodes. However, these additional metallic materials may face issues of secondary pollution and unsustainability. In this study, a metal-free and sustainable nanomaterial, namely cysteamine covalently functionalized graphene (GSH), was found to lead to a 6-fold boost in the Cd2+ sensitivity of the screen-printed carbon electrode (SPCE), while the sensitivities to Pb2+ and Cu2+ were not influenced in simultaneous detection. The selective enhancement could be attributed to the grafted thiols on GSH sheets with good affinity to Cd2+ ions based on Pearson's hard and soft acid and base principle. More intriguingly, the GSH-modified SPCE (GSH-SPCE) featured high reusability with extended cycling times (23 times), surpassing the state-of-art SPCEs modified by non-covalently functionalized graphene derivatives. Last, the GSH-SPCE was validated in tap water., Peer reviewed