MoSi2N4 monolayers for volatile organic compound detection and early assessment of pond health in shrimp aquaculture systems

Early detection of volatile organic compounds (VOCs) produced during microbial decomposition is crucial for preventing water-quality deterioration and disease outbreaks in intensive shrimp aquaculture. Herein, spin-polarized, van der Waals-corrected density functional theory, combined with thermodynamic and electronic transport analyses, was used to investigate the surface chemistry and sensing properties of pristine and transition-metal-functionalized MoSi 2 N 4 monolayers toward dimethylamine (DMA), trimethylamine (TMA), and dimethyl sulfide (DMS). The pristine monolayer interacts weakly with these VOCs, whereas Ni-atom functionalization strengthens adsorption and provides the most promising sensing performance among the systems studied. This improvement is associated with Ni-induced electronic states that enhance adsorbate–surface orbital hybridization, alter the work function, and produce measurable changes in the calculated current–voltage (I-V) response. Langmuir adsorption analysis predicts higher equilibrium surface coverage, while the effects of humidity and interfering gases on the predicted response are limited. The distinct I-V responses to DMA, TMA, and DMS suggest a route to distinguishing these compounds. Together, the adsorption, surface-coverage, and transport results identify Ni-functionalized MoSi 2 N 4 as a promising material for experimental evaluation in chemiresistive sensors for shrimp-pond monitoring.