Search Results (2)

Zinc oxide nanoparticles (ZnO NPs) are widely used and exposed to the soil environment, but their effect on soil nitrous oxide (N₂O) emissions remains unclear. In this study, a microcosm experiment was conducted to explore the effects of different ZnO NPs concentrations (0, 100, 500, and 1000 mg kg⁻¹) on N₂O emissions and associated functional genes related to N₂O amendment with carbon (C) or nitrogen (N) substrates. Partial least squares path modeling (PLS-PM) was used to explore possible pathways controlling N₂O emissions induced by ZnO NPs. In the treatment without C or N substrates, 100 and 500 mg kg⁻¹ ZnO NPs did not affect N₂O production, but 1000 mg kg⁻¹ ZnO NPs stimulated N₂O production. Interestingly, compared with the soils without ZnO NPs, the total N₂O emissions in the presence of different ZnO NPs concentrations increased by 2.36–4.85-, 1.51–1.62-, and 6.28–8.35-fold following C, N and both C & N substrate amendments, respectively. Moreover, ZnO NPs increased the functional genes of ammonia-oxidizing bacteria (AOB amoA) and nitrite reductase (nirS) and led to the exhaustion of nitrate but reduced the gene copies of ammonia-oxidizing archaea (AOA amoA). In addition, the redundancy analysis results showed that the AOB amoA and nirS genes were positively correlated with total N₂O emissions, and the PLS-PM results showed that ZnO NPs indirectly affected N₂O emissions by influencing soil nitrate content, nitrifiers and denitrifiers. Overall, our results showed that ZnO NPs increase N₂O emissions by increasing nitrification (AOB amoA) and denitrification (nirS), and we highlight that the exposure of ZnO NPs in agricultural fields probably results in a high risk of N₂O emissions when coupled with C and N substrate amendments, contributing to global climate warming. Full article

The oxygen vacancy (V_O) is known as the main compensation center in p-type ZnO, which leads to the difficulty of fabricating high-quality p-type ZnO. To reduce the oxygen vacancies, we oxidized Zn₃N₂ films in oxygen plasma and successfully prepared p-type ZnO:N films at temperatures ranging from room temperature to 300 °C. The films were characterized by X-ray diffraction (XRD), non-Rutherford backscattering (non-RBS) spectroscopy, X-ray photoelectron spectroscopy, photoluminescence spectrum, and Hall Effect. The results show that the nitrogen atoms successfully substitute the oxygen sites in the ZnO:N films. The film prepared at room temperature exhibits the highest hole concentration of 6.22 × 10¹⁸ cm⁻³, and the lowest resistivity of 39.47 Ω∙cm. In all ZnO:N films, the V_O defects are reduced significantly. At 200 °C, the film holds the lowest value of V_O defects and the strongest UV emission. These results imply that oxygen plasma is very efficient in reducing V_O defects in p-type ZnO:N films, and could greatly reduce the reaction temperature. This method is significant for the development of ZnO-based optoelectronic devices. Full article