An Ag nanoclusters (AgNCs)@UiO-66(Zr) assembly within a micropipette forms a confined nanochannel-based electrochemical platform for the sensitive detection of H2S released from T bacteria. It exhibits excellent performance in a broad concentration range (0.1 nM to 100 μM) and achieves a low detection limit of 0.1 nM, facilitated by the specific recognition between Ag and sulfide ions.