Zn-doped TiO2 nanoparticles for glutamate sensors

TiO2 has been widely used in catalysis because of its superior catalytic properties. The enhancement of catalytic performance can generally be achieved through doping. In the present study, Zn-doped TiO2 nanoparticles (at a Zn doping level of 2.5, 5, and 10 mol%) were synthesized by the solution combustion technique and characterized to examine their potential usage in sensor applications. The bandgap energies and electrocatalytic activities of the synthesized nanoparticles were microstructurally investigated. The results revealed the presence of anatase nanoparticles with average sizes of 9–14 nm, which agglomerated into clusters with sizes in the range of 78–107 nm. The Zn concentrations did not significantly affect the chemical compositions, but the particles exhibited slight refinement with an increase in the Zn dopant. Narrower bandgaps were observed in the nanoparticles with higher Zn concentrations. The electrocatalytic activities were evaluated by cyclic voltammetry and found that TiO2 nanoparticles with 2.5 mol% Zn had the most prominent activities. Sensitivity, measured in glutamate solutions with concentrations between 0.001 and 1000 mM ranged from 2.47 to 7.20 × 10−6 mA mM−1 cm−2, which were comparable with those reported by other researchers. The TiO2 nanoparticles with 2.5 mol% Zn exhibited fair selectivity and reusability. The oxidation peak current degraded by 12.5%, after 200 cycles of measurement in glutamate solution. The results suggested that TiO2 nanoparticles doped with 2.5 mol% Zn are potential candidates for glutamate-sensing applications.