Density functional theory study on sensing properties of g‐C 3 N 4 sheet to atmospheric gasses: Role of zigzag and armchair edges

The ability of the polymer‐based graphitic carbon nitride (g‐C 3 N 4 ) as a gas sensor toward NO, NO 2 , CO, CO 2 , SO 2 , SO 3 , and O 2 gasses is assessed using density functional theory (DFT) calculations in terms of energetic and electronic transport characteristics. In particular, this study is aimed to explore the role of zigzag and armchair edges of the g‐C 3 N 4 sheet on sensing performances. The electronic properties of adsorption systems, such as Bader charge analysis, band gaps, work function, and density of states (DOS), are used to understand the interaction between the adsorbed gas molecules and the g‐C 3 N 4 sheet. Our calculated results indicate that SOx (SO 3 and SO 2 ) gasses have higher adsorption energies on the g‐C 3 N 4 sheet than other gasses. Furthermore, the transport properties, such as current–voltage (I‐V) and resistance‐voltage (R‐V) curves along the zigzag and armchair directions are calculated using the non‐equilibrium Green's function (NEGF) method to understand the performance of the g‐C 3 N 4 sheet as a prominent conductive/resistive sensor. The I‐V/R‐V results indicate that the zigzag g‐C 3 N 4 sheet has excellent sensing ability toward SOx gasses at low applied voltages. However, the presence of H 2 O degrades the sensing performance of the armchair g‐C 3 N 4 sheet. Theoretical recovery time has also been calculated to evaluate the reusability of g‐C 3 N 4 sheet‐based gas sensors. Our results reveal that the zigzag g‐C 3 N 4 sheet‐based sensing device has a remarkably high sensitivity (>300%) and selectivity toward SOx gasses and has the potential to work in a complex environment.