Nanopattern-Assisted Direct Growth of Peony-like 3D MoS2/Au Composite for Nonenzymatic Photoelectrochemical Sensing.

The chalcogenide material MoS2 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 MoS2 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 MoS2 nanosheets supported by nanohole-patterned TiO2 and composited with gold deposits. The direct growth resulted in enhanced electrical conductivity between the substrate and 3D-standing MoS2 nanosheets and thus the uniform distribution of gold electrodeposits from the MoS2 lattice. The hybrid 3D MoS2/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 MoS2 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 MoS2/gold nanocomposite electrode in comparison with other morphologies. We acquired the Peony-like 3D MoS2/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.