Highly stable urea sensor based on ZnO nanorods directly grown on Ag/glass electrodes

Vertically aligned zinc oxide nanorods (ZnO NRs) were directly grown on Ag sputtered glass substrate by a low-temperature solution route. The fabricated urea sensor (glass/Ag/ZnO NRs/urease) showed a high sensitivity of 41.64 μA/mM cm2, wide linear range 0.001–24.0 mM, and low detection limit of 10 μM. The low value of the Michaelis–Menten constant K M app = 0.328     mM indicates the high affinity of urease towards the urea. The directly synthesized ZnO NRs on the electrode expressively increases NRs attachment and its specific surface area. These features further results in high enzyme loading and enhanced sensor efficiency. The urea sensor showed an excellent anti-interference ability against electroactive species.