In‐Situ Growth of 2D MOFs as a Molecular Sieving Layer on SnS ₂ Nanoflakes for Realizing Ultraselective H ₂ S Detection

Abstract 2D transition metal dichalcogenides (TMDs) have emerged as promising materials for advanced gas sensing platforms owing to their abundant active edge sites, high surface area, and mechanical flexibility. However, TMDs encounter low selectivity issues as they show high responses to a variety of gases, impeding their practical use for gas discrimination. Herein, it is demonstrated that in situ growth of 2D breathable zeolitic imidazolate framework‐leaf (ZIF‐L) dramatically enhances the selectivity of 2D SnS ₂ ‐based gas sensors to H ₂ S. ZIF‐L selectively allows the permeation of the target gas, H ₂ S, while blocking interfering gases, including C ₃ H ₉ N, NH ₃ , and volatile organic compounds. The ZIF‐L/SnS ₂ sensor shows ultrahigh response (1440% resistance change) and exceptional selectivity (response ratio > 10.2 about interfering gases) to 50 ppm of H ₂ S with a low theoretical detection limit of 3.61 ppb. First‐principles calculations elucidate the molecular sieving effect of ZIF‐L, including size exclusion and adsorptive sieving, supporting the mechanism of the outstanding selectivity. Additionally, a monolithic and flexible ZIF‐L/SnS ₂ sensor using a polyethylene terephthalate substrate proves the potential of ZIF‐L/TMDs heterostructures for flexible applications. This study provides a novel and promising strategy for tuning gas selectivity and developing high‐performance flexible chemical sensors using a MOF‐based molecular sieving layer.