Realizing reliable online detection of characteristic gases (H2, C2H4, CO, and CO2) in lithium-ion batteries is crucial to maintain the safe and stable operation of power equipment and new energy storage power plants. In this study, transition metal Ptn (n = 1, 3, and 4) clusters are attached to MoSe2 nanosheets for the first time based on density functional theory using the perfect crystalline facet modification method, and the adsorption characteristics and electronic behaviors of H2, C2H4, CO, and CO2 are investigated and enhanced. The results show that Ptn (n = 1, 3, and 4) is reliably chemically connected to the substrate without any significant deformation of the geometry. The adsorption properties as well as the band gap, DOS, and LUMO-HOMO are optimized for the modified Gas/Ptn (n = 1, 3, and 4)-MoSe2 system. The large electronic states near the Fermi level are further activated by the modification process, and Pt-MoSe2 and Pt4-MoSe2 can serve as battery state characteristic gas sensors suitably according to the detection needs of specific target gases, whereas Pt3-MoSe2 can be used as a good adsorbent for effective and reliable scavenging of battery state characteristic gases and is further applied to energy and power equipment and new energy storage power plants.