The chalcogenide material MoS 2 has been recognized as a promising candidate for photoelectrochemical (PEC) applications due to its enhanced photocatalytic and electrocatalytic activities. However, few reports have been focused on the designated catalytic MoS 2 for the nonenzymatic PEC sensing of small molecules. Here, we report on a novel in situ and fab-free method for the direct growth of three-dimensional (3D) porous Peony-like MoS 2 nanosheets supported by nanohole-patterned TiO 2 and composited with gold deposits. The direct growth resulted in enhanced electrical conductivity between the substrate and 3D-standing MoS 2 nanosheets and thus the uniform distribution of gold electrodeposits from the MoS 2 lattice. The hybrid 3D MoS 2 /gold nanocomposite demonstrated enhanced abundance of exposed catalytic edge sites and improved optic and electrical coupling, which ultimately led to excellent photoelectrochemical activities. We performed full characterization of the morphology, crystallinity, lattice configuration, and optical properties of hybrid MoS 2 nanosheets via field emission scanning microscope, high-resolution transmission electron microscopy, and energy-dispersive X-ray, Raman, and UV−vis spectroscopies. The 3D COMSOL simulation also confirmed enhanced electric field distribution at the interface of the proposed 3D MoS 2 /gold nanocomposite electrode in comparison with other morphologies. We acquired the Peony-like 3D MoS 2 /Au composite for photoelectrochemical sensing of glucose in buffer and diluted plasma solutions with a very low limit of detection of 1.3 nM and superb sensitivity in plasma. Overall, we have successfully synergized both electrical and optical merits from individual components to form a novel composite, which offered an effective scaffold for the development of PEC sensors.

Recently, molybdenum disulfide (MoS2) has received remarkably attention due to its excellent optical and electrical properties. Notably, the narrow bandgap of transition metal dichalcogenide (TMDC) MoS2 makes it a promising candidate for photoelectrochemical (PEC) applications. Direct growth of MoS2 via hydrothermal synthesize offers improved electrical conductivity between the MoS2 and the substrate, which allows for better application and electrical signal readings as a result of elevated electron transfer routs compared with drop-casted MoS2. Here, we studied the effect of hydrothermal growth time of MoS2 nanosheets on the morphology evolution as well as the PEC sensing properties. The time evolution studies conducted in the range of 2-10 hours. We used surface characterization method such as field emission scanning electron microscopy and analytical techniques such as chronoamperometry, cyclic voltammetry and electrochemical impedance spectroscopy to study the morphology evolution and PEC sensing properties. Our results revealed that the direct growth of MoS2 not only enhances the sensor signal but also encourages nanocomposites of MoS2 with gold- a key to simultaneouse amplification of the optical and electrical properties. Effect of applied bias potential in the range of 0.45-0.85 V vs. Ag/AgCl on photocurrent response was also investigated. We further used 3D COMSOL simulation to assess the effect of gold thickness on the electric field intensity of the sensing MoS2/Au electrodes. Eventually, we studied sensitive and selective detection of glucose as an important molecule in the human body. Our developed MoS2/Au composite demonstrated a very low limit of detection (1.3 nM) and excellent sensitivity for non-enzymatic PEC sensing of glucose. Moreover, the selectivity of the fabricated sensor were examined by monitoring the photocurrent responses towards different interfering agents under illumination.