Augmented hydrogen adsorption on metal (Mg,Mn) doped α-phase TeO2: A DFT investigation

TeO₂, as a promising gas sensor material, has been extensively studied for its capacity to detect hydrogen with high sensitivity. First-principles calculations were applied to explore the adsorption properties of hydrogen (H₂), carbon dioxide (CO₂), methane (CH₄), and hydrogen sulfide (H₂S) on TeO₂ doped with either Mg or Mn to explore this compound's potential as hydrogen sensors. Hydrogen is more readily adsorbed on pure-TeO₂, Mg–TeO₂ and Mn–TeO₂ than CO₂, CH₄ and H₂S molecules by calculating their adsorption energy and charge transfer; the sequence of adsorption strength is H₂>H₂S > CO₂>CH₄. The hydrogen molecules and pure-TeO₂, Mg–TeO₂ and Mn–TeO₂ form H–O bonds with lengths of 0.98, 0.98 and 0.99 Å, respectively, indicating that chemical adsorption is dominant between them. The adsorption of hydrogen leads to significant changes in the density of states (DOSs) of pure-TeO₂, Mg–TeO₂ and Mn–TeO₂, which may lead to changes in their electrical conductivity. Moreover, the larger diffusion coefficients for hydrogen on the surfaces of pure-TeO₂, Mg–TeO₂ and Mn–TeO₂ relative to other gases indicates that hydrogen diffuses readily in TeO₂-based sensing materials, and the higher gas concentration contributes to improvements in response performance. This finding offers a theoretical basis for experimental explorations of the influence of metal dopants on TeO₂ hydrogen sensing performance.