Stabilizing Co, Ni and Cu on the h-BN surface: Using O O bond activation to probe their performance as single atom catalyst

Two-dimensional Cu-doped G/h-BN/G heterostructures for highly sensitive gas detection: an ab initio study

Two-dimensional materials like graphene and h-BN have drawn significant interest for gas sensing applications due to their high surface-to-volume ratio and exceptional physical properties. This study introduces a novel approach involving a 2-D G/h-BN/G heterostructure doped with a Cu atom to develop a highly sensitive gas sensor. The intermediate h-BN layers support the Cu dopant and enhance the electrical sensitivity by constraining the offset current. Density functional theory and non-equilibrium Green's function formalisms are employed to investigate the geometry, stability, and electrical properties of the G/h-BN/G structure with the Cu dopant at various vacancy sites, alongside exploring the adsorption behavior of six different gas molecules (NO2, CO, NH3, PH3, HCN, and HO2). Results reveal that doping Cu in the B vacancy and the Stone-Wales defect yields highly stable structures with promising electrical characteristics for gas sensing applications. Gas molecules exhibit a higher tendency to adsorb onto the Cu-doped structure compared to the pristine G/h-BN/G, demonstrating a stronger impact on current flow. The Cu-doped structures display robust electrical sensitivity toward NO2, CO, NH3, and HCN molecules, and the significant gap in current modulation for each gas indicates the potential for distinguishing different gas molecules. Hence, incorporating the Cu dopant in the G/h-BN/G heterostructures emerges as a promising platform for gas sensing applications.

The single metal atom (Ni, Pd, Pt) anchored on defective hexagonal boron nitride for oxidative desulfurization

Single-atom catalysts (SACs) have attracted great attention for various chemical reactions because of their strong activity, high metal utilization ratio, and low cost. Here, by using the density functional theory (DFT) method, the stability of a single VIII-group metal atom (M = Ni, Pd, Pt) anchored on the defective hexagonal boron nitride (h-BN) sheet and its possible application in oxidative desulfurization (ODS) are investigated. Calculations show that the stability of the single M atom embedded in the h-BN surface with B and N vacancies is strikingly enhanced compared to that on the perfect h-BN surface. The catalytic activities of the defective h-BN-supported single metal atom are further studied by the activation of molecular oxygen and subsequent oxidation of dibenzothiophene (DBT). O2 is activated to the super-oxo state with large interaction energies on three M/VN surfaces. However, among the three M/VB surfaces, only Pt/VB performs efficient activation of O2. The oxidation of DBT proceeds in two steps; the rate-determining step is the initial step, in which activated O2 oxidizes DBT to produce sulfoxide. By comparing the energy barrier in the first reaction step, both Ni/VN and Pt/VB are revealed as promising candidates for the ODS reaction.

Transition Metal and N Doping on AlP Monolayers for Bifunctional Oxygen Electrocatalysts: Density Functional Theory Study Assisted by Machine Learning Description

It is vital to search for highly efficient bifunctional oxygen evolution/reduction reaction (OER/ORR) electrocatalysts for sustainable and renewable clean energy. Herein, we propose a single transition-metal (TM)-based defective AlP system to validate bifunctional oxygen electrocatalysis by using the density functional theory (DFT) method. We found that the catalytic activity is enhanced by substituting two P atoms with two N atoms in the Al vacancy of the TM-anchored AlP monolayer. Specifically, the overpotential of OER(ORR) in Co- and Ni-based defective AlP systems is found to be 0.38 (0.25 V) and 0.23 V (0.39 V), respectively, showing excellent bifunctional catalytic performance. The results are further presented by establishing the volcano plots and contour maps according to the scaling relation of the Gibbs free-energy change of *OH, *O, and *OOH intermediates. The d-band center and the product of the number of d-orbital electrons and electronegativity of the TM atom are the ideal descriptors for this system. To investigate the activity origin of the OER/ORR process, we performed the machine learning (ML) algorithm. The result indicates that the number of TM-d electrons (N_e), the radius of TM atoms (r_d), and the charge transfer of TM atoms (Q_e) are the three primary descriptors characterizing the adsorption behavior. Our results can provide a theoretical guidance for designing highly efficient bifunctional electrocatalysts and pave a way for the DFT-ML hybrid method in catalysis research.

Structure, assembly mechanism and magnetic properties of heterometallic dodecanuclear nanoclusters DyIII4MII8 (M = Ni, Co)

Two isostructural heterometallic dodecanuclear nanoclusters [Dy4Co8(μ3-OH)8(L)8(OAc)4(H2O)4]·3EtOH·3CH3CN·H2O (1) and [Dy4Ni8(μ3-OH)8(L)8(OAc)4(H2O)4]·3.5EtOH·0.5CH3CN·5H2O (2) with different assembly mechanisms are presented here.