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

Abstract

A Cu(2)O-doped RuO(2) 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. Cu(2)O-RuO(2)-SE displayed a linear DO response from 0.5 to 8.0 ppm (log[O(2)], -4.73 to -3.59) within a temperature range of 9-30 degrees C. The maximum sensitivity of -47.4 mV/decade at 7.27 pH was achieved at 10 mol% Cu(2)O. Experimental evaluation of the Cu(2)O-doped RuO(2)-SE demonstrated that the doping of RuO(2) not only improves its structure but also enhances both sensor's selectivity and antifouling properties. Selectivity measurements revealed that 10 mol% Cu(2)O-doped RuO(2)-SE is insensitive to the presence of Na(+), Mg(2+), K(+), Ca(2+), NO(3)(-), PO(4)(2-) and SO(4)(2-) ions in the solution in the concentration range of 10(-7)-10(-1) mol/l.