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

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.