This paper focuses on investigating the CO2 (Carbon Dioxide) capture capability of tantalum (Ta) doped 2-dimensional (2-D) MoSe2 (Molybdenum diselenide) monolayer through first-principle calculations. Understanding CO2 capture is crucial for exploring methods to reduce CO2 into hydrogen, a green fuel. Employing Density Functional Theory (DFT), the electronic properties of Ta-doped MoSe2 for CO2 sensing have been explored. In this study covered absorption energy, charge transfer and work function of CO2 molecule on Ta-doped MoSe2. The negative formation and binding energy (−6.62, −8.09 eV) show the electronic stability of undoped and Cu-doped MoSe2 ML respectively. Substituting Ta atom in place of Se-vacancy into the MoSe2 monolayer led to an enhanced conduction property in adsorbed molecules, reflected by an improved bandgap. The results reveal a significant alteration in the electrical and chemical behavior of Ta-doped MoSe2 upon CO2 adsorption. These findings highlight Ta-doped MoSe2 as a promising, stable candidate for gas sensing applications.