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Abstract
Transition-metal dichalcogenide (TMD) monolayers have recently gained attention, driven by their growing potential for applications in electronics, gas sensing, and electrocatalysis. However, the lack of coordinatively unsaturated surface sites makes TMDs' basal plane chemically inert, leading to technological limitations. One promising approach to increase the activity is single-atom doping. Nevertheless, the optimal doping strategies remain unclear, due to the limited understanding of the extent, selectivity, and underlying mechanisms driving this modulation. Consequently, this study aims to explore the upper limits of TMD reactivity and the underlying mechanisms by investigating boron-doped MoTe2 (B-MoTe2), which was identified as the most active candidate following systematic testing of 22 p-block dopants in our previous work. We employed density functional theory (DFT) methods to simulate the adsorption of 9 molecules: N2O, NO2, NO, N2, CO2, CO, O2, H2O, and H2, chosen to probe the available modes of interaction and their availability. Four distinctive behaviors were observed: (i) dissociation of NO2, O2, and H2, (ii) substitution of B with N atom for NO, (iii) chemisorption of CO, and H2O, and (iv) physisorption of N2 and CO2. This selectivity arises from the molecule's intrinsic bonding affinity with the dopant and the geometric constraints imposed by the sheet. When the potential of doping is effectively harnessed, the enhanced reactivity results from boron adopting more favorable orbital hybridization during molecule adsorption. Thus, B-MoTe2 becomes significantly more reactive than pristine MoTe2, exhibiting adsorption strengths several tens of times greater, which profoundly impacts the structure of the adsorbates. The presented picture is completely different from interactions on pristine MoTe2, governed by van der Waals forces. The demonstrated novel physicochemical properties underscore the potential of MoTe2 to be finely tuned for applications in catalysis and gas sensing. Moreover, the new insights offer a foundation for developing more effective doping strategies.
