Tailored Fabrication of Defect-Rich Ion Implanted CeO2-x Nanoflakes for Electrochemical Sensing of H2O2

As an alternative to H2O2 enzymatic biosensing devices, non-enzymatic CeO2-based biosensors have shown improved sensibility, robustness, and shelf lives. The redox capability in CeO2 and rapid switching between its oxidation states facilitate the formation of structural vacancy defects that serve as active sites. This work reports a novel approach for synthesis of defect-rich CeO2-x-based nanoflakes using a controllable electrochemical-based deposition at low temperatures (45 degrees-65 degrees C) followed by low-energy ion implantation. Among the nanoflakes, Mo-implanted CeO2-x exhibited outstanding sensitivity of 4.96 x 10(-5 )A center dot mM(-1) cm(-2) within the linear range of 0.05-10 mM. Moreover, the ion-implanted samples yielded high sensing stability and electronic conductivity. The former was achieved through the multi-valence charge transfer between Ce and the implanted ions that caused the reduction of Gibbs free energies required for the formation/retention of the defects. The latter was due to the narrowing of the electronic bandgap of CeO2-x by creation of defect-induced midgap states.

Automated summary

Non-enzymatic CeO2-based biosensors are an alternative to H2O2 enzymatic biosensing devices, offering improved sensibility, robustness, and shelf lives. The redox capability in CeO2 and rapid switching between its oxidation states facilitate the formation of structural vacancy defects that serve as active sites. This study presents a novel approach for synthesizing defect-rich CeO2-x-based nanoflakes through controllable low-temperature electrochemical deposition followed by low-energy ion implantation. The Mo-implanted CeO2-x nanoflakes exhibited exceptional sensitivity, high sensing stability, and electronic conductivity due to valence charge transfer and defect-induced midgap states.