Transition Metal Atoms Modified Ge-Vacancy and Perfect GeSe Monolayers for SF₆ Decomposition Gases Detection and Scavenging

To develop a semiconductor type sensor for monitoring and scavenging the SF<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> decomposition gas (SO<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub>, H<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub>S, and SOF<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub>), the systematical study on adsorption properties and transport properties of transition metal (TM) atom decorated GeSe monolayers with and without Ge-vacancy are deployed based on density functional theory (DFT). The numerical results demonstrate that replacing one Ge atom in GeSe monolayer with TM (Cr, Mn, Fe, and Co) still retain its semiconducting natures, but its band gap is narrowed. In contrast, the band gaps of Mn-, Fe-, and Co-decorated perfect GeSe would gradually disappear with the increasing of doping concentration. The same dopant in the Ge-vacancy surface transfer more electron to GeSe monolayer than that in perfect case, while the TM-modified perfect GeSe monolayers exhibit greater adsorption capability and the stronger chemical interaction toward SO<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub>, H<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub>S, and SOF<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub>. Further, the recovery time of 1.82 s and the larger change in band gap demonstrate that Cr-replaced GeSe monolayer can be as a reusable SOF<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> sensor at room temperature. The Cr- and Fe-replaced GeSe monolayers have excellent sensitivity for SO<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> detection, and the Mn-replaced configuration only can detect H<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub>S molecule. The sensitivity of Cr-decorated perfect GeSe toward SO<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> superior to H<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub>S as semiconductor type gas sensor. In contrast, The remarkable molecular deformation and strong chemical reaction verify the potential of Cr- and Mn-decorated perfect monolayer as gas scavenger for removing H<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub>S and SOF<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub>. The data provides the basis for the design of SF<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> decomposition gas sensor and sweeper based on GeSe monolayer by two types of TM decoration methods.