Krik Soufiane, Valt Matteo, Gaiardo Andrea, Fabbri Barbara, Spagnoli Elena, Caporali Maria, Malagù Cesare, Bellutti Pierluigi, Guidi Vincenzo
Department of Physics and Earth Sciences, University of Ferrara, Via G. Saragat 1/C, 44122 Ferrara, Italy.
Sensing Technologies Lab, Faculty of Science and Technology, Free University of Bozen-Bolzano, Piazza Università 1, 39100 Bolzano, Italy.
ACS Omega. 2022 Mar 10;7(11):9808-9817. doi: 10.1021/acsomega.2c00078. eCollection 2022 Mar 22.
In the field of layered two-dimensional functional materials, black phosphorus has attracted considerable attention in many applications due to its outstanding electrical properties. It has experimentally shown superior chemical sensing performance for the room temperature detection of NO, highlighting high sensitivity at a ppb level. Unfortunately, pristine black phosphorus demonstrated an unstable functionality due to the fast degradation of the material when exposed to the ambient atmosphere. In the present work, a deepened investigation by density functional theory was carried out to study how nickel decoration of phosphorene can improve the stability of the material. Further, an insight into the sensing mechanism of nickel-loaded phosphorene toward NO was given and compared to pristine phosphorene. This first-principles study proved that, by introducing nickel adatoms, the band gap of the material decreases and the positions of the conduction band minimum and the valence band maximum move toward each other, resulting in a drop in the conduction band minimum under the redox potential of O/O , which may result in a more stable material. Studying the adsorption of O molecules on pristine phosphorene, we also proved that all oxygen molecules coming from the surrounding atmosphere react with phosphorus atoms in the layer, resulting in the oxidation of the material forming oxidized phosphorus species (PO ). Instead, by introducing nickel adatoms, part of the oxygen from the surrounding atmosphere reacts with nickel atoms, resulting in a decrease of the oxidation rate of the material and in subsequent long-term stability of the device. Finally, possible reaction paths for the detection of NO are given by charge transfer analyses, occurring at the surface during the adsorption of oxygen molecules and the interaction with the target gas.
在层状二维功能材料领域，黑磷因其出色的电学性能在许多应用中备受关注。实验表明，它在室温下检测一氧化氮时具有卓越的化学传感性能，在十亿分之一水平上表现出高灵敏度。不幸的是，由于暴露在环境大气中时材料快速降解，原始黑磷表现出不稳定的功能。在本工作中，通过密度泛函理论进行了深入研究，以探讨镍修饰磷烯如何提高材料的稳定性。此外，深入研究了负载镍的磷烯对一氧化氮的传感机制，并与原始磷烯进行了比较。这项第一性原理研究证明，通过引入镍原子，材料的带隙减小，导带最小值和价带最大值的位置相互靠近，导致导带最小值在O/O的氧化还原电位以下下降，这可能导致材料更稳定。研究氧分子在原始磷烯上的吸附，我们还证明了来自周围大气的所有氧分子都与层中的磷原子反应，导致材料氧化形成氧化磷物种（PO ）。相反，通过引入镍原子，周围大气中的部分氧与镍原子反应，导致材料氧化速率降低，从而使器件具有后续的长期稳定性。最后，通过电荷转移分析给出了检测一氧化氮的可能反应路径，这些反应路径发生在氧分子吸附和与目标气体相互作用期间的表面。
