UiO-66 Surface-Modified CuPc/SrTiO3 Heterojunction Photoelectrode for Ultrasensitive and Highly Selective Photoelectrochemical Detection of Nitric Oxide

Abstract Nitric oxide (NO) is an important gaseous signaling molecule involved in vascular regulation, neural transmission, and immune responses. However, its short lifetime, low steady-state concentration, and dynamic release behavior make real-time in situ monitoring challenging, particularly in phototriggered NO release systems. Herein, a dual-functional photoelectrochemical (PEC) platform was developed by integrating a UiO-66 surface layer with a CuPc/SrTiO3 heterojunction photoelectrode for simultaneous NO detection and dynamic monitoring of nitroglycerin-triggered NO release. The CuPc/SrTiO3 heterojunction promotes photogenerated charge separation, while the UiO-66 layer enriches NO through abundant Zr–O active sites, enhancing the interfacial response. Under illumination, nitroglycerin releases NO while the photoelectrode generates a stable photocurrent. The released NO consumes photogenerated holes, producing a concentration-dependent photocurrent decrease, enabling real-time kinetic analysis. The PEC platform exhibited a linear range of 0.063–10 nM, a detection limit of 0.019 nM (S/N = 3), and a quantification limit of 0.063 nM (S/N = 10), with good selectivity, stability, and reproducibility. The platform also enabled continuous monitoring of nitroglycerin-induced NO release in a simulated physiological environment, providing a PEC-based strategy for investigating photoinduced gas generation and release kinetics.