Mapping the Nexus of Electrical Conductivity and Gas Sensing for Tailored Design of Transition Metal (Cu, Co, Ni)-Based Bimetallic 2D Conjugated MOF

Bimetallic 2D π-conjugated HHTP metal–organic frameworks (2D c -HHTP-MOFs), which with improved electrical conductivity, extended active sites, and customizable band gaps, have attracted a greater interest than their monometallic counterparts in electronics. However, there is no study on engineering bimetallic 2D c -HHTP-MOFs containing tunable 3 d transition metal units in the field of chemiresistive sensors yet. Here, we present a mapping of electrical conductivity–gas sensing that enables the creation of bimetallic 2D M/Cu-HHTP c -MOFs (M = Co, Ni) with tailored metal nodes. We used crystal structure refinement, density functional theory (DFT) calculations, in situ diffuse reflectance infrared Fourier transform spectroscopy ( in situ DRIFT), and conductivity measurements to explore the role of metal nodes in the topology structure, ammonia (NH 3 ) adsorption capacity, energy band structure, and electrical conductivity. Consequently, we show that designing 2D Co/Cu-HHTP c -MOFs with both enhanced gas sensing and high electrical conductivity (σ ≈ 1.50 × 10 –3 S·cm –1 ) can be applied in constructing high-performance room-temperature NH 3 chemiresistor, exhibiting higher sensitivity, better selectivity, reduced baseline resistance drift (<10%), and more superior repeatability and stability, compared with reported monometallic powdered 2D c -HHTP-MOFs. This work paves the way for designing high catalytic activity of bimetallic 2D c -MOFs without compromising their electrical conductivity.