Regulation of Electrical Properties of ZrOxNy by Oxygen Doping and Zirconium Vacancies

Transition metal oxynitrides are important materials in electronic devices, electrocatalysis, machinery industry and other fields, according to their excellent properties, such as high sensitivity to temperature and high electron transport characteristics. Especially in sensor and MOS applications, transition metal oxynitrides with semiconductor properties play an important role in the sensitivity and frequency response of sensors. Here, we study the effects of different concentrations of zirconium vacancy (VZr) and oxygen doping on the ZrN structure, and calculate the formation energies and density of states of ZrOxNy in different element ratios by density functional theory. The results show that the introduction of VZr and oxygen doping promote the Fermi level of ZrOxNy to move towards the valence band and conduction band, respectively. The structure of the non-degenerate semiconductor ZrOxNy can be constructed at Zr0.425N0.569O0.006. Taking ZrOxNy as an example, this work proposes a method to regulate the electrical properties of transition metal oxynitrides by introducing zirconium vacancy/oxygen doping, which greatly promotes the rapid discovery of novel transition metal oxynitrides semiconductor materials.

Photoelectric and Magnetic Properties of Boron Nitride Nanosheets with Turbostratic Structure and Oxygen Doping

Turbostratic and oxygen doping (3.7 atom % ) hexagonal boron nitride nanosheets (TO-BNNSs) with abundant defect sites, were synthesized by pyrolyzing the mixture of melamine cyanurate and boric acid. Systematic analyses reveal a highly disordered structures and covalent oxygen-doping in the TO-BNNSs. These features endow the product with increased unpaired electrons, localized charge asymmetry and spin polarization. While compared with bulk h-BN, the optical bandgap of TO-BNNSs drop down to ~5.2 from ~5.7 eV, dielectric constant raised from ~2.1 to ~2.4, the saturation magnetic moment increased from ~0.011 to ~0.033 emu/g, and the coercivity enlarged from ~73.56 to ~367.39 Oe. These results suggest that h-BN materials with turbostratic structure and heteroatom-doping have extensive application prospect in the fields of nanoscale optics, electronics and magnetics.

Surface Oxygen Injection in Tin Disulfide Nanosheets for Efficient CO2 Electroreduction to Formate and Syngas

Surface chemistry modification represents a promising strategy to tailor the adsorption and activation of reaction intermediates for enhancing activity. Herein, we designed a surface oxygen-injection strategy to tune the electronic structure of SnS2 nanosheets, which showed effectively enhanced electrocatalytic activity and selectivity of CO2 reduction to formate and syngas (CO and H2). The oxygen-injection SnS2 nanosheets exhibit a remarkable Faradaic efficiency of 91.6% for carbonaceous products with a current density of 24.1 mA cm−2 at −0.9 V vs RHE, including 83.2% for formate production and 16.5% for syngas with the CO/H2 ratio of 1:1. By operando X-ray absorption spectroscopy, we unravel the in situ surface oxygen doping into the matrix during reaction, thereby optimizing the Sn local electronic states. Operando synchrotron radiation infrared spectroscopy along with theoretical calculations further reveals that the surface oxygen doping facilitated the CO2 activation and enhanced the affinity for HCOO* species. This result demonstrates the potential strategy of surface oxygen injection for the rational design of advanced catalysts for CO2 electroreduction.

Stress and Strain Prediction of Zirconium Nitride under Oxygen Doping and Vacancy Introduction

Zirconium nitride (ZrN) is an important material for the mechanical industries due to its excellent properties such as excellent wear resistance, high hardness, etc. In practical applications, it is necessary to study how to regulate the mechanical properties of materials to meet the needs of different applications. To better understand the influence of vacancies and oxygen on the mechanical property of ZrN, we studied the tensile strength of the ZrN with oxygen atom doping and zirconium vacancy introduction by ab initio density functional theory. The mechanical property changes of modified ZrN in three crystallographic directions (<001>, <110>, and <111>) were calculated. The results show that the tensile strength of ZrN can be increased by oxygen doping at a certain concentration, while that of ZrN can be decreased by the introduction of zirconium vacancy.