A TiO2 nanosheet-g-C3N4 composite photoelectrochemical enzyme biosensor excitable by visible irradiation

•A photoelectrochemical enzyme biosensor.•A TiO2 nanosheet-g-C3N4 composite as a biosensor scaffold.•A photoelectrochemical biosensor operable using visible excitation.

In this work, g-C3N4 and TiO2 nanosheets were synergistically employed as a novel composite for developing a scaffold of a photoelectrochemical enzyme biosensor. In this way, we have improved the poor visible light excitation of TiO2 and retarded the photo-generated charge recombination on g-C3N4 to achieve an enhanced response at the photoelectrochemical biosensor, compared to that generated by the corresponding biosensors consisting of each individual component. Using glucose oxidase as a model enzyme, the biosensor was demonstrated to show strong visible light activity towards the enzyme mediated glucose oxidation. We have also observed a 350% enhanced photocurrent compared to that at a g-C3N4 based ITO electrode. In addition, the high specific surface area and excellent biocompatibility of TiO2 nanosheets have also positively contributed to the performance of the photoelectrochemical enzyme biosensor with a 0.05-16 mM linear range and a 0.01 mM glucose detection limit.

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