Polyaniline Functionalization of Defective 1T-MoS₂ Nanosheets for Improved Electron and Mass Transfer: Implications for Electrochemical Sensors

Simultaneously improving electron and mass transfer processes is full of challenges for electrode material design. To this end, three-dimensional (3D) porous electrode materials were obtained via covalent combination between defective 1T-MoS 2 nanosheets and polyaniline (PANI) through hydrothermal/solvothermal processes and surface polymerization reactions. Our experimental results and density functional theory calculations jointly reveal that PANI molecules can not only intercalate into van der Waals (vdW) gaps of 1T-MoS 2 nanosheets but also chemically adsorb onto S-vacancy clusters (via Mo–N covalent bonds), rather than single atomic S-vacancies due to steric effects. Similarly, the geometric structure of PANI in the vdW gaps of 1T-MoS 2 nanosheets possesses a flat-lying configuration for better stability. Compared to surface functionalization, interlayer intercalation has more profound effects on electronic structures for improving electrochemical properties, including reduced band gaps, small effective electron masses, and high mobility. As a proof-of-concept application, the 1T-MoS 2 –PANI nanocomposites were used to construct an electrochemical sensor for trace Cu 2+, which exhibits high sensitivity and selectivity with a wide linear range from 3 to 450 nM and a low detection limit because of excellent conductivity, a low contact barrier against electron transfer, high mass transfer, and strong coordination interactions between PANI and Cu 2+ .