FULL PAPER Highly improved carbon dioxide sensitivity and selectivity of black phosphorene sensor by vacancy doping: A quantum chemical perspective Mohammad Ghashghaee 1 | Mehdi Ghambarian 2 1 Faculty of Petrochemicals, Iran Polymer and Petrochemical Institute, Tehran, Iran 2 Gas Conversion Department, Faculty of Petrochemicals, Iran Polymer and Petrochemical Institute, Tehran, Iran Correspondence Mehdi Ghambarian, Gas Conversion Department, Faculty of Petrochemicals, Iran Polymer and Petrochemical Institute, P.O. Box 14975-112, Tehran, Iran. Email: m.ghambarian@ippi.ac.ir Abstract The adsorption and sensing properties of a carbon dioxide (CO 2 ) molecule on the pristine (BP) and vacancy-doped (DP) black phosphorusmono layers have been inves- tigated using the periodic density functional theory at Heyd-Scuseria-Ernzerhof (HSE06)/triple-zeta valence polarization (TZVP). For both sensors, the most stable structures among the recognized possibilities preferred a linear configuration for car- bon dioxide, with a shorter equilibrium distance (2.13 Å) on the defect-containing surface. Although carbon dioxide was weakly physiosorbed on both phosphorene sensors (up to -2.52 kcal/mol), the defect-engineered material presented highly improved sensitivity (by a factor of 6.6) to CO 2 compared to the pristine layer. The former was also a (2.6 times) better work function sensor of carbon dioxide. At the same time, recovery was extremely fast (lasting for 70 ps at most) at room tempera- ture. The selectivity coefficient of carbon dioxide was also strikingly high (64.0). The improved nanosensor would be a step forward in the rational design of highly sensi- tive and reusable detectors of carbon dioxide. KEYWORDS black phosphorene, carbon dioxide, DFT, environment, sensor 1 | INTRODUCTION Cost-effective chemosensors are currently among the crucial components of modern life with applications in different areas, from chemical plants to social security purposes. Nanosensors of various types, including solid electrolyte sensors, metal oxide detectors, electrochemical detection systems, and graphene-based sensors, are therefore widely studied. Nanostructures and 2D materials are of particular interest in this respect for their relatively higher mass-based efficiencies and peculiar behaviors. [1–7] Of the 2D materials, black phosphorus (BP) can be mentioned, which enjoys a renewed interest after its few-layer structures were prepared via mechanical exfoliation. [8–11] Recently, an ambient-stable BP has been fabricated using pulsed laser exfoliation. [12] Relative to the other allo- tropes of phosphorus structures, namely, the red and white phosphorus, BP is known to be more chemically stable and more tolerant to ignition by fire. [9,11] More interestingly, the single-layer BP plane, often termed as (black) phosphorene, has shown outstanding anisotropic and electronic properties that confer high electron/heat conductivity on this 2D material. [13–16] These characteristics make phosphorene a fascinating candidate for the design and fabrication of sensitive sensors and electronic devices. [9–11] The properties of BP and its single-layer structure can be further modulated using defect engineering, decoration, functionalization, and dop- ing, which have recently been reviewed by the same authors. [10,17,18] These modifications can tune the electronic behavior of the surface toward the molecules of interest and thereby improve its adsorption, sensitivity, and selectivity for a particular purpose. However, the knowledge in this area is still relatively in its infancy, and there is much room for exploration. Therefore, studies along these lines are currently underway. Received: 12 February 2020 Revised: 4 April 2020 Accepted: 20 April 2020 DOI: 10.1002/qua.26265 Int J Quantum Chem. 2020;e26265. http://q-chem.org © 2020 Wiley Periodicals, LLC 1 of 12 https://doi.org/10.1002/qua.26265