Cu-decorated HfS2 and Cu-embedded HfS2 for adsorption and gas sensing of lithium-ion thermal runaway gases: A DFT study

Lithium-ion batteries are found in every corner of our lives, and safety concerns have received significant attention. Therefore, monitoring thermal runaway gases from lithium-ion batteries is crucial for human safety. In this paper, density functional theory (DFT) is used to establish the adsorption models of Cu-decorated HfS2 (Cu@HfS2) and Cu-embedded HfS2 (Cu-HfS2), taking C2H4, CH4, H2, CO and CO2 as target gases. By calculating the adsorption energy, charge transfer, charge differential density, energy band, density of states, work function, sensing response, and recovery time, it is found that Cu@HfS2 has a strong adsorption effect on C2H4, CO and H2, and Cu-HfS2 has a better adsorption effect on CH4 and CO2. At room temperature, the chemisorption of CO by Cu-HfS2 is stable, the sensing response is better, and the desorption time is shorter, so it has the potential to be used as a resistive gas sensor. This study provides theoretical guidance for exploring the influence of different metal doping methods on the adsorption characteristics and gas sensing properties of HfS2.