Influence of Different Dissolved Gases on Electrocatalytic Nitrate Sensing Performance at Cu‐Modified Au Electrode

The present study investigates the electrocatalytic nitrate reduction reaction (NRR) on a Cu/Au electrode surface in a neutral pH potassium chloride (KCl) environment saturated with nitrogen, oxygen, and carbon dioxide, three of the most abundant atmospheric gases. The electrode was characterized using OCP, EIS, SEM, EDX, XPS, and XRD to assess its electrochemical properties, catalytic feasibility, and surface morphology. Results indicated that nitrate ions undergo a consecutive reduction process ( → → ) on the Cu/Au electrode. O 2 saturated environment impeded the NRR process through O 2 adsorption on the electrode surface prior to the → conversion. In contrast, CO 2 saturated condition enhanced the reaction by neutralizing the NRR byproduct ions, thus accelerating the overall NRR kinetics. Under CO 2 environment the NRR process was found more facile compared to that of other two gases. NRR took place at a peak potential of −0.71 V and −1.06 V for the first and second reduction wave, respectively. Kinetic analysis showed that the reduction reactions in presence of CO 2 followed first‐order, diffusion‐limited kinetics. The Cu/Au electrode exhibited high sensitivity (3.49×10 −1 μA μM −1 ) with an LOD of 0.46 μM for nitrate detection, and finally demonstrated excellent performance in real sample analysis.