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The mediation of vacancy in catalysts is crucial for the enhancement of oxidant activation. Here the boron nitride loaded with Co mixed oxides (Co 2 O 3 -CoO) and boron vacancy (B v) catalyst (Co/BN-X) was prepared to degrade sulfamethoxazole (SMX) by activating peroxymonosulfate (PMS). Under dark condition, Co/BN-3+PMS system can completely remove SMX in surface water within 15 min, and its removal efficiency constant (0.5154 min−1) was 4.0 and 6.7 times greater than those of Co/BN-2+PMS (0.1284 min−1) and Co/BN-1+PMS (0.0771 min−1), respectively. The system showed excellent performance in different influencing factors and cyclic experiments, and exhibited good practical application potential in secondary effluent. Electron paramagnetic resonance, radical quenching and electrochemical tests certified that singlet oxygen (1O 2) was the major active species, followed by •O 2 –, and SO 4 •–, further elaborating the activation pathway of PMS in Co/BN-3+PMS system. The density functional theory (DFT) calculations confirmed that CoO and PMS-O 2 sites were the main reaction sites, and the existence of B v reduced the adsorption energy of Co/BN-3 for PMS. This work reveals the synergistic effect between Co oxide sites and B v on the catalyst surface and offers a potential modification method to accelerate Fenton-like reaction. [Display omitted] • We prepare Co mixed oxides boron nitride (BN) catalyst with boron vacancy (B v). • Co/BN-3 + PMS system can ultrafast remove drugs in the surface water and dark. • 1O 2 is the main active species, followed by •O 2 –, and SO 4 •– • DFT calculations reveal that PMS-O 2 and CoO sites are the main interaction sites. • The introduction of B v reduces the adsorption energy of Co/BN-3 for PMS. [ABSTRACT FROM AUTHOR]

We compare and contrast the physisorption behavior of imidazolium and butyltrimethylammonium based ionic liquids (ILs) on mono-vacant nitrogen and boron defective hexagonal boron nitride nanoflakes (h-BNNF) using M06-2X/cc-pVDZ level of theory. The presence of defects on the nanoflakes results in an increase in IL binding energy by ~ 1–27 kcal/mol partly due to the lowering of the energy band in the defective nanoflakes. Imidazolium based ILs adsorb energetically more favorably on h-BNNF-V B than on h-BNNF-V N while butyltrimethylammonium based ILs prefer to adsorb on h-BNNF-V N . Upon adsorption of imidazolium ILs on the nanoflakes, an increase in both HOMO and LUMO orbital energies is observed - resulting in net increase in HOMO-LUMO energy gap (E g ) value and chemical hardness (η). On the other hand, the adsorption of butyltrimethylammonium ILs leads to an increase in HOMO energy and a decrease in LUMO energy of the h-BNNF-V B nanoflake thereby lowering the E g and η values of defective nanoflakes. The absorption spectra of mono-vacant surfaces undergo shifts upon IL adsorption. The first absorption peak at 296 nm is red-shifted while the second absorption peak at 421 nm is blue-shifted. The magnitude of the first absorption peak for the h-BNNF-V B …IL complexes follow the order of h-BNNF-V B …[Btma][Y] > h-BNNF-V B… [Bmim][Y] (Y = BF 4 − , PF 6 − , Tf 2 N − ) consistent with greater binding energies and energy gaps of imidazolium based complexes in comparison to their butyltrimethylammonium counterparts. Generally, it is concluded that the modulation of opto-electronic properties of IL-functionalized h-BNNF surfaces is largely provided by the defects and to a lesser extent by the choice of IL. [ABSTRACT FROM AUTHOR]

Abstract: First principle calculations for a hexagonal (graphene-like) boron nitride (g-BN) monolayer sheet in the presence of a boron-atom vacancy show promising properties for capture and activation of carbon dioxide. CO2 is found to decompose to produce an oxygen molecule via an intermediate chemisorption state on the defect g-BN sheet. The three stationary states and two transition states in the reaction pathway are confirmed by minimum energy pathway search and frequency analysis. The values computed for the two energy barriers involved in this catalytic reaction after enthalpy correction indicate that the catalytic reaction should proceed readily at room temperature. [Copyright &y& Elsevier]

First-principles calculations were carried out to calculate the formation energy, migration barrier and electronic properties of a resistive memory model based on hexagonal boron nitride (h-BN) in the presence of an active metal and a boron vacancy (V B) using density functional theory (DFT). Following the benchmark of the exchange correlation functional and the calculated parameters of monolayer h-BN, a model of a multilayer h-BN vertical stack with distribution states of SW-5577 defects was proposed. For four active metal dopants (Ti, Ag, Cu and Ni), a preference towards substitution sites (S1) with the lowest dopant formation energies (DFEs) was identified, which enhanced the formation of adjacent V B , especially for the nearest neighbour. Furthermore, a low concentration of Ti dopant in the closest location to the initial position of the migration path would drastically reduce the migration barrier of the V B between layers. Finally, Ti dopants with two and three V B neighbours in the same layer significantly improved the conductivity and the formation of conducting channels because of the improvement of charge distribution in the resistance model, which was demonstrated by DOS plots, band-decomposed charge density and Bader charge. Our present work can provide theoretical guidance for the rational design and device optimization of h-BN-based RRAM devices. • A multilayer vertical stack with SW-5577 defects was proposed for theoretical calculation of h-BN based RRAM. • A preference towards substitution site (S1) with the lowest DFEs was identified for Ti, Ag, Cu and Ni dopants. • The closest Ti dopant to the initial position would drastically reduce the migration barrier of the V B between layers. • The increase in the number and spatial distribution of V B is beneficial to the surrounding electron localization. [ABSTRACT FROM AUTHOR]

[Display omitted] • Thermal NaBH 4 treatment is used to update the surface properties of ɑ-MnO 2. • BV is in situ formed via the wash-away of B dopant during dye elimination process. • BV transforms DO into ROS without extra energy input. • Strong acidity, free Mn3+ site and large pore contribute to adsorptive dye removal. • The treated MnO 2 shows excellent Pb2+ adsorption capacity especially in acid matrix. Oxygen vacancy (OV), one frequently designed structural anion defect, can transport active oxygen species towards multi-phase pollutant oxidation by activating oxygen molecules or chemical oxidants. However, dissolved oxygen (DO), a desirable oxidant source for water organics degradation, is very difficult to be directly utilized by OV-abundant metal oxides without extra heat or light input. To solve this problem, in this study another anion defect, i.e. , boron vacancy (BV), was successfully incorporated into ɑ-MnO 2 via a two-step method, i.e. , thermal NaBH 4 treatment for boron doping followed by in situ wash-away of boron during organic dye elimination process. The NaBH 4 -modified ɑ-MnO 2 exhibited much higher Rhodamine B (RhB) elimination than the original one. BV is capable of transforming DO into 1O 2 , OH and O 2 − radicals at 30 °C and without extra energy input, completely mineralizing RhB into inorganic carbon. Besides, NaBH 4 -induced strong acid sites, free Mn3+ species and large pore size contributed to adsorptive RhB removal. For the original ɑ-MnO 2 , surface lattice oxygen was the key oxidant for dye degradation. Malachite Green, Congo Red, Orange I and Methyl Blue were further tested as target substrates. The NaBH 4 -treated ɑ-MnO 2 presented superiority over the pristine sample in adsorptive Pb2+ removal as well. [ABSTRACT FROM AUTHOR]

W-doped ZrB 2 ceramics were hot-pressed at 1800–2100 °C by using W additive. The effects of W doping on the densification, microstructure, and high temperature strength of ZrB 2 ceramics were investigated. The reaction between ZrB 2 and W resulted in the formation of WB, ZrB and boron vacancies in ZrB 2 -x. The solid solution formed by dissolving WB in ZrB 2 -x has core-shell structure, inhibited the grain growth and densification of ZrB 2 ceramics. (W,Zr)B converted to liquid promoted densification at 2100 °C, and dissolved the oxygen from the surface of ZrB 2 powders. The ZrB 2 ceramics with 3–10 vol% W exhibited fine microstructures and high grain boundary strength. The cleaning boundary produced by WB significantly improved the flexural strength of ZrB 2 ceramics at 25–1600 °C. (Zr,W)B precipitated from vacancy-rich (Zr,W)B 2-x solid solution under tensile stress at 1600 °C. • The solid solution formed by dissolving WB in ZrB 2 -x inhibited the densification of ZrB 2 ceramics. • WB dissolved the oxygen from ZrB 2 powders and markedly improved strength of ZrB 2 ceramics. • (Zr,W)B precipitated from vacancy-rich (Zr,W)B 2-x solid solution under tensile stress at 1600 °C. [ABSTRACT FROM AUTHOR]