Bipolar resistive switching behavior of carbon nitride supported copper oxide nanoparticles

g-C3N4@CuO electrostatic self-assembly toward Ralstonia solanacearum: Insights from cytomembrane and motility disruption

BACKGROUND

Ralstonia solanacearum, a notorious and refractory bacterial plant pathogen, threatens multiple vegetable crops and causes significant economic loss in agriculture. Long-term use of traditional medicines not only increases the problem of drug resistance, but also causes great environmental pollution. Therefore, there is an urgent need to develop new agents with high efficacy and low toxicity.

RESULTS

In this study, we have synthesized and characterized graphitic carbon nitride incorporated copper oxide composite (g-C3N4@CuO), which showed higher antimicrobial effect than graphitic carbon nitride nanosheets (g-C3N4 nanosheets) and copper oxide nanoparticles (CuONPs). Ralstonia solanacearum exposed to g-C3N4@CuO exhibited higher levels of oxygen toxicity, cell membrane damage, DNA damage, motility disruption and even cell death compared to g-C3N4 nanosheets and CuONPs. In addition, g-C3N4@CuO was more effective in the control of tobacco bacterial wilt than g-C3N4 nanosheets and CuONPs.

CONCLUSION

Thus, this study provides a new perspective on g-C3N4@CuO control of bacterial diseases in crops, and the mechanism is related to the destruction of cell membrane damage and motility disruption. © 2024 Society of Chemical Industry.

Intensive harmonized synapses with amorphous Cu2O-based memristors using ultrafine Cu nanoparticle sublayers formed via atomically controlled electrochemical pulse deposition

Resistive random-access memory (RRAM) devices have significant advantages for neuromorphic computing but have fatal problems of uncontrollability and abrupt resistive switching behaviors degrading their synaptic performance. In this paper, we propose the electrochemical design of an active Cu2O layer containing a strategic sublayer of ultrafine Cu nanoparticles (U-Cu NPs) to form uniformly dispersed conducting filaments, which can effectively improve the reliability for analog switching of RRAM-based neuromorphic computing. The electrochemical pulse deposited (EPD) U-Cu NPs are linked to the bottom electrode through a semi-conductive path within the bottom Cu2O layer, since the EPD is preferentially carried out on the conductive sites. All Cu2O films with U-Cu NPs are developed in situ in the single electrolyte bath without any pause. The proposed U-Cu NPs can concentrate the external electric field and can generate conductive filament paths for analog resistive switching. The applied electric field was uniformly spread to U-Cu NPs at the center of the active layer and displays resistive switching behavior via multiple conductive filaments. This shows a strong harmony between the resistance-switching characteristics and the analog operation of the active layer. This RRAM device shows outstanding gradual analog switching, great linearity, dynamic range, endurance, precision, speed, and retention characteristics simultaneously and adequately for neuromorphic computing by realizing multiple weak filament-type operation.

Preparation and Antibacterial Activity of Nano Copper Oxide- Loaded Zeolite 10X

Copper oxide nanosheet-loaded zeolite 10X nanocomposites (CuO-zeolite NCs) were successfully prepared by modifying zeolite 10X with CuSO₄ aqueous solution. The formation of copper oxide nanosheets on the surface of zeolite 10X was observed by SEM. The thickness of CuO nanosheets was about 30–40 nm, and the width ranged from 200 nm to 300 nm. The XRD patterns showed that the new diffraction peaks of copper oxide appeared at 35.6° and 38.8°. According to the XPS results, the Cu 2p_3/2 and Cu 2p_1/2 peaks in CuO-zeolite NC were centered at 934.1 eV and 953.8 eV, which could be attributed to Cu(II). The EDS analysis revealed that the energy spectra of calcium gradually decreased as the copper ion concentration increased during the preparation of CuO-zeolite NCs. Meanwhile, the energy spectra of copper increased gradually, and the highest content of copper in CuO-zeolite NCs reached 22.35 wt.%. The BET surface areas of zeolite 10X and CuO-zeolite NCs were 587 and 363 m²/g, respectively, based on the N₂ adsorption–desorption experiment. The antibacterial activities of CuO-zeolite NC were evaluated using Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The antibacterial activities were related to both copper ion content in CuO-zeolite NCs and the particle size of copper oxide. The results showed that nano CuO-loaded zeolite 10X inhibited the activity of E. coli and S. aureus. CuO-zeolite NCs are expected to be further used in antifouling coating.

Investigation of a memory effect in a Au/(Ti-Cu)Ox-gradient thin film/TiAlV structure

This paper presents the results of the analysis of resistive switching properties observed in a Au/(Ti-Cu)Ox/TiAlV structure with a gradient distribution of Cu and Ti along the (Ti-Cu)Ox thin film thickness. Thin films were prepared via multisource reactive magnetron co-sputtering. The programmed profile of the pulse width modulation coefficient during sputtering of the Cu target allowed us to obtain the designed gradient U-shape profile of the Cu concentration in the deposited thin film. Electrical measurements of the Au/(Ti-Cu)Ox/TiAlV structure showed the presence of nonpinched hysteresis loops in the voltage-current plane testifying a resistive switching behavior. Results of optical, X-ray, and ultraviolet photoelectron spectroscopy measurements allowed us to elaborate the scheme of the bandgap alignment of the prepared thin films with respect to the Au and TiAlV electrical contacts. Detailed structure and elemental profile investigations allowed us to conclude about the possible mechanism for the observed resistive switching mechanism.