Single-layer, defect-laden hexagonal boron nitride (dh-BN) is attracting a great deal of attention for its diverse applications: catalysis on the one hand, and single photon emission on the other. As possible probes for identifying some common defects in single-layer h-BN, we present results of ab initio calculations for the adsorption and vibrational characteristics of syngas molecules (H₂, CO, CO₂) on dh-BN containing one of four types of defects: nitrogen vacancy (V_N), boron vacancy (V_B), Stone–Wales defect (SW), and nitrogen substituted by boron (B_N). Through a comparative examination of adsorption features, charge transfer, electronic structure, and vibrational spectrum, we obtain a deep understanding of the interaction of these molecules with dh-BN and the role of the defect states. We find that while CO, CO₂ and atomic hydrogen chemisorb, molecular H₂ physisorbs on dh-BN with the four considered defect types. V_N and V_B show strong affinity for CO and CO₂ since the defect states induced by them lie close to the Fermi level. SW does not favor adsorption of these small molecules, as the process for each is endothermic. In the case of B_N, CO adsorbs strongly but CO₂ only weakly. Vibrational frequencies of notable modes localized at the adsorbed molecules are analyzed and suggested as measures for identification of the defect type. Through a simple comparison of adsorption characteristics of the molecules on these defects, we propose dh-BN with V_N to be a good catalyst candidate for CO₂ hydrogenation.

中文翻译：

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合成气分子作为二维六方氮化硼缺陷的探针：它们的吸附和振动

单层，负载缺陷的六方氮化硼（dh -BN）因其多样化的应用而引起了广泛的关注：一方面是催化，另一方面是单光子发射。作为识别单层h-BN中某些常见缺陷的可能探针，我们提供了从头算的结果，计算了合成气分子（H ₂，CO，CO ₂）在dh -BN上的吸附和振动特征，其中dh- BN包含四种类型之一缺陷的数量：氮空位（V _N），硼空位（V _B），斯通-威尔斯缺陷（SW）和被硼取代的氮（B _N）。通过对吸附特征，电荷转移，电子结构和振动光谱的比较研究，我们对这些分子与dh -BN的相互作用以及缺陷状态的作用有了深入的了解。我们发现，虽然CO，CO ₂和原子氢化学吸附，但是分子H ₂在dh -BN上具有四种被认为是缺陷类型的物理吸附。V _N和V _B对CO和CO ₂具有很强的亲和力，因为它们引起的缺陷态接近费米能级。SW不利于这些小分子的吸附，因为每个过程都是吸热的。在B _N的情况下，CO吸附强烈，但CO₂只弱。分析了位于吸附分子上的显着模式的振动频率，并提出了作为识别缺陷类型的措施。通过简单比较分子在这些缺陷上的吸附特性，我们提出具有V _N的dh -BN是CO ₂加氢的良好催化剂候选物。