Potentiometric sensor using sub-micron Cu2O-doped RuO2 sensing electrode with improved antifouling resistance

A Cu2O-doped RuO2 sensing electrode (SE) for potentiometric detection of dissolved oxygen (DO) was prepared and its structure and electrochemical properties were analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron microscopy (XPS) and energy-dispersive spectroscopy (EDS) techniques. Cu2O-RuO2-SE displayed a linear DO response from 0.5 to 8.0 ppm (log[O2], −4.73 to −3.59) within a temperature range of 9–30 °C. The maximum sensitivity of −47.4 mV/decade at 7.27 pH was achieved at 10 mol% Cu2O. Experimental evaluation of the Cu2O-doped RuO2-SE demonstrated that the doping of RuO2 not only improves its structure but also enhances both sensor's selectivity and antifouling properties. Selectivity measurements revealed that 10 mol% Cu2O-doped RuO2-SE is insensitive to the presence of Na+, Mg2+, K+, Ca2+, NO3−, PO42− and SO42− ions in the solution in the concentration range of 10−7–10−1 mol/l.