Assembly of MoS₂ nanosheet-TiO₂ nanorod heterostructure as sensor scaffold for photoelectrochemical biosensing

Highlights: •MoS₂ nanosheets were grown on TiO₂ nanorods to obtain a heterostructure. •The thickness of MoS₂ nanosheets in the composite is much thinner than that of MoS₂ microspheres. •Photoelectrochemistry (PEC) of the heterostructure is superior to that of the single component under visible irradiation. •Glucose oxidase (GOx) PEC biosensor was developed based on the heterostructure. •The performance of PEC GOx sensor was evaluated -- Abstract: In the present work, MoS₂ nanosheets were composited with TiO₂ nanorods to obtain a heterostructure with improved photoelectrochemical (PEC) performance. TiO₂ nanorods were initially prepared using a hydrothermal method, and then MoS₂ nanosheets were synthesized using TiO₂ nanorods as the substrates. Various spectroscopic and microscopic methods were used to investigate the morphology and composition of the composite. Electrochemical impedance spectroscopy was also conducted to demonstrate the excellent electrical conductivity of the composite. The bioactivity of glucose oxidase (GOx) to glucose was validated with cyclic voltammetry in air-saturated solution. Finally, a PEC biosensor was fabricated by immobilizing GOx on MoS₂ nanosheet-TiO₂ nanorod composite modified ITO electrode. Owing to the high specific surface area, good conductivity, excellent biocompatibility and small band gap associated with this composite, the PEC glucose biosensor exhibited a dynamic range of 0.1–10.5 mM, sensitivity of 0.81 μA mM⁻¹, and a detection limit of 0.015 mM within the visible spectrum.