The effects of size and content of cerium oxide nanoparticles on a composite sensor for hydroxyl radicals detection

[Display omitted] •An electrode modified with a CeO2 nanoparticles/graphene oxide composite can detect •OH concentrations as low as 0.085 mM.•8 nm CeO2 nanoparticles showed the highest sensor response to hydroxyl radicals.•Composites containing 50:50 CeO2 nanoparticles:graphene oxide weight ratios provided the largest sensor response to •OH.•The aggregation of CeO2 nanoparticles impacted the sensor efficiency negatively. A screen-printed carbon electrode was modified with a composite comprised of cerium oxide nanoparticles and graphene oxide (CeNP/GO) to be employed as a sensing device for hydroxyl radicals (•OH) detection. CeO2 nanoparticles (CeNPs) were synthesized using a precipitation method, and the CeNP/GO composites were fabricated using a low-temperature solution process. Scanning Transmission Electron Microscopy (STEM) and Energy Dispersive Spectroscopy (EDS) were used to determine the average size and the distribution of CeNPs on the composites. X-Ray powder Diffraction (XRD) confirmed the composition of the CeNP/GO composites. Cyclic voltammetry (CV) was used to characterize the interaction of the composite sensor with OH generated by the Fenton reaction. The effects of size and content of CeNPs on the sensor response with OH were examined using 8, 12, and 16 nm CeNPs with loadings of 10, 25, 50, 75, and 90 wt% CeNPs on the CeNP/GO composite. The CeNP/GO composite with 8 nm CeNPs showed the largest sensor response to OH for all the tested ratios. Furthermore, the composites containing 50 wt% of CeNPs demonstrated the largest sensor responses in the detection of OH. The lowest detection limit (0.085 mM) was observed with the composite consisting of 8 nm CeNPs with a CeNP:GO ratio of 50:50. It is thought that the lower content of GO and the aggregation of CeNPs as the loading ratio increased above 50 wt% resulted in lower current changes and poor sensor performance.