Anab initiostudy of catechol sensing in pristine and transition metal decoratedγ-graphyne

Transition Metal (Cu, Pd, and Ag)-Modified Nb2S2C Monolayer for Highly Efficient Catechol Sensing: A First-Principles Investigation

Motivated by recent advancements and the escalating application of two-dimensional (2D) gas or molecule sensors, this study explores the potential of the 2D Nb2S2C monolayer for detecting biomolecule catechol (Cc), whose excess concentration is highly dangerous to living beings. We use first-principles density functional theory (DFT) calculations to assess the Cc sensing performance of pure and transition metal (TM = Cu, Pd, Ag)-modified Nb2S2C monolayers. The Nb2S2C monolayer belonging to the new class of synthesized 2D materials, TM carbo-chalcogenides (TMCC), combines distinctive properties from both TM dichalcogenides and TM carbides and exhibits physisorption (-0.66 eV) toward the Cc molecule. Notably, the surface modifications with these TMs significantly enhanced the adsorption energy of Cc. The chemisorption of the Cc molecule on the Pd to Cu-modified monolayer is demonstrated with adsorption energies ranging from -1.09 to -1.3 eV and is due to the robust charge transfer and orbital interactions between the valence orbitals of TMs and Cc. In addition, the modification of the surface by TM leads to an increased work function sensitivity toward the Cc molecule. The study establishes the thermal stability at 300 K and dynamic stability of TM-Nb2S2C through ab initio molecular dynamics (AIMD) simulations and Phonon calculations, respectively. The theoretical estimation of achievable recovery time at 400 and 450 K for Pd and Ag and at 500 K for the Cu-modified Nb2S2C monolayer, respectively, confirms the potential practical application of the sensor for Cc detection. These compelling characteristics position the Nb2S2C monolayer as a promising nanomaterial for detecting Cc molecules in the environment.

Catechol Sensing Performance of Pd-Functionalized Two-Dimensional Polyaramid: A DFT Investigation

Catechol (Cc) molecule adsorption on a pristine and transition metal (TMs = Sc, Pd, and Cu)-functionalized two-dimensional polyaramid (2DPA) monolayer is systematically studied by the first-principles density functional theory method. The weak physisorption (-0.29 eV) and charge transfer of the Cc molecule with p-2DPA result in a very quick recovery time (150 μs), hindering the Cc sensing capability of p-2DPA. Although TM functionalization greatly improved the adsorption ability, the Pd-functionalized 2DPA was shown to be the best choice for Cc adsorption due to the reasonable adsorption energy of -1.39 eV and expedited charge transfer between the Cc and Pd atom. The change of band gap and, hence, the conductivity of the Pd-2DPA system in response to the adsorption of the Cc molecule demonstrate its higher sensitivity than that of p-2DPA. The work function sensitivity of Pd-2DPA upon the Cc adsorption is also investigated. In addition to the change in the electronic properties, the change in the optical properties of Pd-2DPA after Cc adsorption is also analyzed. The structural stability of Pd-2DPA is validated by performing ab initio molecular dynamics simulations at 300 K. The complete desorption of the Cc molecule from Pd-2DPA is attained by annealing the material at 550 K under visible light (τ = 5.4 s) and at 450 K under UV light (τ = 3.7 s). Moreover, the higher diffusion energy barrier of +1.35 eV confirmed that the functionalized Pd atoms did not diffuse through the crystal to form clusters. This study could lay a theoretical foundation for developing possibly new-generation sensors for detecting Cc molecules.