One Stone, Three Birds: SnO₂ Nanosheet Arrays toward Self‐Powered Visible‐Blind UV Photodetection with High Responsivity and Rejection Ratio

Abstract Photoelectrochemical‐type ultraviolet photodetectors (PEC UV PDs) with simple fabrication processes and high sensitivity have attracted ever‐growing attention. However, the self‐powered performance of PEC UV PDs is still unsatisfying. Herein, the SnO₂ nanosheet array (NSA) photoanodes are fabricated and their good self‐powered UV detection capability is demonstrated. The 3D structure of SnO₂ NSA not only improves the interfacial charge transfer and carrier transport but also enhances UV absorption. Therefore, the self‐powered SnO₂ NSA‐based PEC UV PDs exhibit excellent performance with an ultrahigh responsivity of 207.12 mA W⁻¹, an excellent UV–visible rejection ratio (R₂₅₄/R₄₅₅ of 3395), a fast response time (25 ms), and good stability under 254 nm illumination, demonstrating one of the recorded‐high‐performance in the recently reported PEC UV PDs. This work provides more options for developing high‐performance PEC UV PDs.