Improved antifouling resistance of electrochemical water quality sensors based on Cu2O-doped RuO2 sensing electrode

Improvement in both sensor's characteristics and antifouling resistance has been achieved by utilising Cu2O as a dopant to the sub-micron-sized RuO2 sensing electrode (SE) of the water quality sensors. 20 mol% Cu2O-doped RuO2-SE has exhibited a linear response to dissolved oxygen (DO) between 0.5 and 8.0 ppm at various temperatures with the sensitivity slope of −46 mV/decade. This paper describes the structural properties and characteristics of thin-film Cu2O-doped RuO2-SE subjected to a field trial in sewerage environment for three months. Selectivity measurements revealed that the presence of PO43−, SO42−, Ca2+, Mg2+, Li+, NO3−, F−, Na+, K+ and Cl− in the test solution had no significant effect on the sensor's emf. Long-term stability test in harsh sewerage environment demonstrated that the Cu2O-doped RuO2-SE possesses improved antifouling resistance compared to RuO2-SE. Morphology and crystalline structure of Cu2O-doped RuO2-SE were studied by scanning electron microscopy (SEM), X-ray diffraction (XRD) technique and Raman spectroscopy.