Self‐Powered SiC‐Based Photoelectrochemical Ultraviolet Photodetectors for Robust Underwater Optical Communication Against Full Aquatic Environments

Abstract Manipulating the interfacial and surface carrier dynamics within nanostructured semiconductors is pivotal for advancing the electrical and optical performances of photoelectrochemical (PEC) photodetectors (PDs), particularly for durable underwater optical communication systems. Herein, a highly responsive and robust self‐powered PEC UV PDs based on SiC/Au heterojunction nanoarrays is explored, by leveraging the synergistic effect from localized surface plasmon resonance (LSPR) of Au nanoparticles (NPs), heterojunction interfacial engineering, integrated self‐supporting photoelectrode architecture, 1D nanoarray benefits, and inherent chemical stability of SiC. SiC nanowire (NW) arrays are fabricated via anodic oxidation and subsequently decorated with tailored densities of Au NPs using controlled sputtering. The as‐assembled SiC‐based PEC PDs demonstrate exceptional UV (375 nm) photodetection behaviors with rapid response ( τ _r / τ _d , 86.5/170.95 ms), high responsivity ( R _λ , 1244.95 mA W ⁻¹ ), excellent detectivity ( D ^* , 6.35 × 10 ¹¹ Jones), and remarkable external quantum efficiency ( EQE , 412.45%). Moreover, they exhibit broad pH tolerance and excellent long‐term stability against full aquatic environments. This work provides a strategic approach for designing high‐performance self‐powered PEC PDs for reliable underwater optical communication, such as liquid environmental monitoring, ocean exploration, and biomedical detection.