Adsorption\nand Sensing Performance of Transition Metal\nDecorated Graphene Quantum Dots for AsH<sub>3</sub>, NH<sub>3</sub>, PH<sub>3</sub>, and H<sub>2</sub>S

We have conducted a systematic study employing density\nfunctional\ntheory (DFT) and quantum theory of atoms in molecules (QTAIM) to explore\nthe gas sensing capabilities of nitrogen-doped single vacancy graphene\nquantum dots (SV/3N) decorated with transition metals (TM = Mn, Co,\nCu). We have studied the interactions between TM@SV/3N and four different\ntarget gases (AsH<sub>3</sub>, NH<sub>3</sub>, PH<sub>3</sub>, and\nH<sub>2</sub>S) through the computation of adsorption energies, charge\ntransfer, noncovalent interaction, density of states, band gap, and\nwork function for 12 distinct adsorption systems. Our comprehensive\nanalysis included an in-depth assessment of sensors’ stability,\nsensitivity, selectivity, and reusability for practical applications.\nOur findings indicate that the Co@SV/3N surface strongly interacts\nwith PH<sub>3</sub>, with the highest adsorption energy (−1.15\neV). It shows remarkable sensitivity and selectivity toward PH<sub>3</sub>, making it a promising candidate for PH<sub>3</sub> gas sensing\napplications. Similarly, Mn@SV/3N exhibits high sensitivity and selectivity\ntoward NH<sub>3</sub>, positioning it as a suitable candidate for\nNH<sub>3</sub> gas sensing applications. We believe this study will\nprovide valuable theoretical guidance for developing TM@SV/3N-based\ngas sensors.