A Spear and Shield-Inspired Ar Plasma Safeguard Few-Layer Black Phosphore with Firefighting of Epoxy Resin

Appearing as an innovative and efficient strategy, a facile strategy of a plasma ball mill is carried out to prepare few-layer black phosphorus nanosheets (BPNSs), for abating the fire risk of epoxy resin (EP). A spear and shield-inspired Ar plasma emergeed through a plasma ball mill to prevent Ar@BP nanosheets from oxidation compared with the preparation of BP nanosheets (MBPNSs) in a mechanical ball mill. The absorption coefficient in the synchrotron radiation spectrum is increased by 16.91%, indicating that BP is effectively protected by Ar proof. The Vienna ab initio simulation reveals that the combination of Ar@BP with oxygen cannot proceed spontaneously with the binding energy of 4.44 eV. With the introduction of 1.5 wt% Ar@BP, the total heat release (THR), total smoke release (TSR), total smoke production(TSP), CO, and CO2 yield, compared with that of EP, are descended by 30.40%, 24.41%, 24.10%, 33.23%, and 37.60%, respectively, indicating excellent flame retardancy property. It is attributed to the condensed and gas phase function. Meanwhile, the tensile strength and elongation at break increase by 27.92% and 56.04%, respectively, with the incorporation of 1.5 wt% Ar@BP.

Boosting photoelectrochemical water splitting of bismuth vanadate photoanode via novel co-catalysts of amorphous manganese oxide with variable valence states

Bismuth vanadate (BVO) is a promising photoanode while suffers from sluggish oxygen evolution kinetics. Herein, an ultra-thin manganese oxide (MnO_x) is selected as co-catalyst to modify the surface of BVO photoanode by a facile spray pyrolysis method. The photoelectrochemical measurements demonstrate that surface charge transport efficiency (η_surface) of MnO_x modified BVO photoanode (BVO/MnO_x) is strikingly increased from 6.7 % to 22.3 % at 1.23 V_RHE (reversible hydrogen electrode (V_RHE)). Moreover, the η_surface can be further boosted to 51.3 % at 1.23 V_RHE after applying Ar plasma on the BVO/MnO_x sample_, which is around 7 times higher comparing with that of pristine BVO samples. Additional characterizations reveal that the remarkable PEC performance of the Ar-plasma treated BVO/MnO_x photoanode (BVO/MnO_x/Ar plasma) could be attributed to the increased charge carrier density, extended carrier lifetime and additional exposed Mn³⁺ active sites on the BVO surface. This investigation could provide a new understanding for the design of BVO photoanode with superior PEC performance based on the modification of MnO_x and plasma surface treatment.

Plasma-induced oxygen vacancies enabled ultrathin ZnO films for highly sensitive detection of triethylamine

Metal oxide semiconductor (MOS) thin films hold great promise for electronic devices such as gas sensors. However, the low surface activity of pristine MOS often leads to inferior sensitivity and the sensitization mechanism of ultrathin MOS films has received rare attention. Herein, we report a high performance gas sensor based on plasma-etched ZnO thin films. The ultrathin ZnO films (20 nm) were deposited on SiO₂ wafers by atomic layer deposition (ALD), which enables high-throughput production of sensor devices. The ZnO sensor shows typical n-type conductivity, which is highly variable to the exposure of triethylamine (TEA). Annealing temperature of the films is found to impact the sensor response, revealing calcination at a moderate temperature, i.e. 700 °C, leads to the best response. Further treatment by Ar plasma results in a remarkable decrease of sensor working temperature from 300 °C of untreated films to 250 °C and nearly 4-fold enhancement in the sensor response to 10 ppm TEA. Notably, the plasma-treated ZnO sensor also shows decent response even at room temperature (RT), which has been seldom reported for ZnO-based sensors. Structure and mechanism investigations reveal that the superior sensor properties are derived from the abundant oxygen vacancies generated by Ar plasma etching.

Earthworm-Inspired Ultradurable Superhydrophobic Fabrics from Adaptive Wrinkled Skin

Wrapped by periodically wrinkled skin, soft earthworm shows excellent robustness against sticky soil. Mimicking this deformation adaptability, here, we report an ultradurable superhydrophobic fabric by exploiting the formation of adaptive, soft wrinkled poly(dimethylsiloxane) (PDMS) skins. Uniform wrinkles are created on woven fabric fibers due to the surface instability of PDMS coating with a cross-linking gradient induced by Ar plasma treatment. Both the surface topography of wrinkles and the viscoelasticity of the underlying compliant layer to release stress endow the treated superhydrophobic fabrics with extraordinary durability, withstanding 800 standard laundries or 1000 rubbing cycles under 44.8 kPa. Additionally, superhydrophobic fabrics are self-healable after heating or plasma treatment. This insight of engineering soft skins with periodic submicron surface topography and gradient modulus provides a pathway for the design of ultradurable, multifunctional wearables.

Multiple Vacancies on (111) Facets of Single-Crystal NiFe2 O4 Spinel Boost Electrocatalytic Oxygen Evolution Reaction

Oxygen evolution reaction (OER) as the rate-determining reaction of water splitting has been attracting enormous attention. At present, only some noble-metal oxide materials (IrO₂ and RuO₂ ) have been reported as efficient OER electrocatalysts for OER. However, the high cost and scarcity of these noble-metal oxide materials greatly hamper their large-scale practical application. Herein, we synthesize 100% (111) faceted NiFe₂ O₄ single crystals with multiple vacancies (cation vacancies and O vacancies). The (111) facets can supply enough platform to break chemical bonds and enhance electrocatalytic activity, due to its high density of atomic steps and kink atoms. Compared to NiFe₂ O₄ (without vacancies), the as-synthesized NiFe₂ O₄ -Ar (with vacancies) exhibits a dramatically improved OER activity. The NiFe₂ O₄ -Ar-30 shows the lowest onset potential (1.45 V vs RHE) and the best electrocatalytic OER activity with the lowest overpotential of 234 mV at 50 mA cm^-2 . Furthermore, based on the theoretical calculations that the introduction of multiple vacancies can effectively modulate the electronic structure of active centers to accelerate charge transfer and reaction intermediates adsorption, which can reduce the reaction energy barrier and enhance the activity of electrochemical OER.

How Does Plasma Activated Media Treatment Differ From Direct Cold Plasma Treatment?

OBJECTIVE

The aim of the paper is to investigate the optimum condition for generation of Plasma Activated Media (PAM), where it can deactivate the cancer cells while minimum damage for normal cells.

BACKGROUND

Over past few years, cold atmospheric Plasma-Activated Media (PAM) have shown its promising application in plasma medicine for treatment of cancer. PAM has a tremendous ability for selective anti-cancer capacity in vitro and in vivo.

METHODS

We have analyzed the radicals in air using the optical emission spectroscopy and in culture media using chemical analysis. Further, we have tested the toxicity of PAM using MTT assay.

RESULTS

We observed that more cancer cell death is for the Ar plasma followed by the Ar-N2 plasma, and the least cell death was observed for the Ar-O2 plasma at all treatment times both by direct treatment and through PAM treatment. The concentration of the RNS species is high for Ar-N2 plasma in gas as well as inside the culture media compared to that for pure Ar plasma. However, the difference is significantly less between the Ar plasma treatments and the Ar-N2 plasma treatments, showing that ROS is the main factor contributing to cell death.

CONCLUSION

Among all three feeding gas plasmas the best system is Ar-O2 plasma for direct treatments towards the cancer cells. In addition, the best system for PAM preparation is Ar-N2 at low time treatments (1 min and 2 min) because it has no effect on normal cells, but kills the cancer cells.