Template‐Directed Synthesis of MOF‐Based Sensors for Ultratrace Gas Sensing

ABSTRACT Conductive metal‐organic frameworks (c‐MOFs) offer great promise for sensing applications, yet the controlled fabrication of c‐MOF thin films with defined morphology, thickness, and even orientation remains a significant challenge. Herein, we describe a template‐directed strategy to enable the in‐situ growth of a series of c‐MOFs on polypyrrole@graphene oxide (PPy@GO) nanosheets with variable morphologies and texture. Leveraging the abundant surface functional groups and 2D topological structure of PPy@GO nanosheets, controlled self‑assembly of Ni 3 (HHTP) 2 on their surface is achieved. The growth of Ni 3 (HHTP) 2 on the PPy@GO templates proceeds via a Volmer‐Weber growth mode. The resulting PPy@GO/Ni 3 (HHTP) 2 based sensors with good conductivity and enhanced porosity exhibit sensitive and selective detection toward NO 2 at room temperature with a detection limit of 350 ppb, outstanding compared to the previously reported NO 2 sensors. This excellent NO 2 sensing performance can be attributed to the efficient charge transfer between the adsorbed NO 2 molecules and PPy@GO/Ni 3 (HHTP) 2 verified by multiple characterizations. This work offers a novel strategy for preparing gas‐sensitive materials with salient sensing performance toward practical applications.