Photoelectrochemical Sensor for H₂S Based on a Lead-Free Perovskite/Metal–Organic Framework Composite

Halide perovskites have emerged as a highly promising class of photoelectric materials. However, the application of lead-based perovskites has been hindered by their toxicity and relatively weak stability. In this work, a composite material comprising a lead-free perovskite cesium copper iodide (CsCu₂I₃) nanocrystal and a metal–organic framework (MOF-801) has been synthesized through an in situ growth approach. The resulting composite material, denoted as CsCu₂I₃/MOF-801, demonstrates outstanding stability and exceptional optoelectronic characteristics. MOF-801 may serve a dual role by acting as a protective barrier between CsCu₂I₃ nanocrystals and the external environment, as well as promoting the efficient transfer of photogenerated charge carriers, thereby mitigating their recombination. Consequently, CsCu₂I₃/MOF-801 demonstrates its utility by providing both stability and a notably high initial photocurrent. Leveraging the inherent reactivity between H₂S and the composite material, which results in the formation of Cu₂S and structural alteration, an exceptionally sensitive photoelectrochemical sensor for H₂S detection has been designed. This sensor exhibits a linear detection range spanning from 0.005 to 100 μM with a remarkable detection limit of 1.67 nM, rendering it highly suitable for precise quantification of H₂S in rat brains. This eco-friendly sensor significantly broadens the application horizon of perovskite materials and lays a robust foundation for their future commercialization.