High-Responsivity SiC/TiO2 Photoelectrochemical Ultraviolet Photodetector: Heterojunctions with Fast Response Times and Excellent pH Tolerance

The precise control of the surface properties of low-dimensional nanostructures is a prerequisite for preserving the intrinsic material quality and manipulating the carrier transport behavior to enhance optoelectronic device performance. Herein, a high-responsivity photoelectrochemical (PEC) ultraviolet (UV) photodetector (PD) based on SiC/TiO 2 heterojunction nanowires is developed. The surface of SiC nanowires is decorated with high-quality TiO 2 nanoparticles through a simple hydrothermal process, and a type-II heterojunction is established. The fabricated SiC/TiO 2 heterojunction nanowire PEC PD exhibited excellent photoresponsivity with high responsivity (50.97 mA W −1 ), detectivity (1.07 × 10 12 Jones), and external quantum efficiency (16.85%) under 375 nm ultraviolet illumination. Response and decay times are as low as 0.3 and 0.1 ms, respectively—these values are within the state-of-the-art range for semiconductor nanostructure–based PEC PDs reported thus far. The device also exhibits excellent photoresponsivity and long-term stability under different light intensities, even in harsh universal-pH liquid environments, including acidic, neutral, and alkaline solutions with different concentrations. The elevated photodetection performance of the device is primarily attributed to the effective synergistic effect of the formation of a type-II charge transfer pathway in the SiC/TiO 2 heterostructure, the optimal load capacity of TiO 2 nanoparticles, and the excellent inherent corrosion resistance of SiC and TiO 2 .