Developing highly efficient hydrogen evolution reaction (HER) catalysts in alkaline media is considered significant and valuable for water splitting. Herein, it is demonstrated that surface ...reorganization engineering by oxygen plasma engraving on electocatalysts successfully realizes a dramatically enhanced alkaline HER activity. Taking CoP nanowire arrays grown on carbon cloth (denoted as CoP NWs/CC) as an example, the oxygen plasma engraving can trigger moderate CoOx species formation on the surface of the CoP NWs/CC, which is visually verified by the X‐ray absorption fine structure, high‐resolution transmission electron microscopy, and energy‐dispersive spectrometer (EDS) mapping. Benefiting from the moderate CoOx species formed on the surface, which can promote the water dissociation in alkaline HER, the surface reorganization of the CoP NWs/CC realizes almost fourfold enhanced alkaline HER activity and a 180 mV decreased overpotential at 100 mA cm−2, compared with the pristine ones. More interestingly, this surface reorganization strategy by oxygen plasma engraving can also be effective to other electrocatalysts such as free‐standing CoP, Co4N, O‐CoSe2, and C‐CoSe2 nanowires, which verifies the universality of the strategy. This work thus opens up new avenues for designing alkaline HER electrocatalysts based on oxygen plasma engraving.
A generic strategy, oxygen plasma engraving engineering, is used to trigger more efficient hydrogen evolution reaction (HER) catalytic activity on the surface of cobalt phosphide in an alkaline electrolyte. The promotion of HER activity relies on the in situ construction of a CoOx/CoP interface, where the amount of oxide can be precisely controlled to an appropriate value by the plasma engraving time.
Layered tin disulfide (SnS2) is a vital semiconductor with versatile functionality due to its high carrier mobility and excellent photoresponsivity. However, the intrinsic defects Vs (sulfur ...vacancies), which cause Fermi level pinning (significant metal contact resistance), hinder its electrical and optoelectrical performance. Herein, oxygen plasma treatment is employed to enhance the optoelectronic performance of SnS2 flakes, which results in artificial sub‐bandgap in SnS2. Consequently, the broadband photosensing (300–750 nm) is remarkably improved. Specifically, under 350 nm illumination, the O2‐plasma‐treated SnS2 photodetector exhibits an enhanced photoresponsivity from 385 to 860 A W−1, the external quantum efficiency and the detectivity improve by one order of magnitude as well as increase the photoswitching response improvement by two orders of magnitude for both rising (τr) and decay (τd) time. This artificial sub‐bandgap can both improve the photoresponse and broaden the response spectra, which paves a new path for the applications of optoelectronics.
Herein, oxygen plasma treatment is employed to enhance the optoelectronic performance of SnS2 flakes, which results in an artificial sub‐bandgap in SnS2. Consequently, this artificial sub‐bandgap improves both the photoresponsivity (from 385 to 860 A W−1) and broadens the response spectra (300–750 nm).
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The effects of adsorbent characteristics on its water adsorption performance were investigated using low-temperature oxygen plasma technology (LTOP) as a surface modification method. ...A series of activated carbon fiber (ACF)-based adsorbents was prepared to get further insight into the functions of water vapor adsorption behavior with textural property and surface chemistry. The result shows that LTOP treatment does not alter drastically the physical surface properties and simultaneously functionalize oxygen-containing functional groups (OFGs) especially carboxyl groups on the ACF surface when the treatment time and effective output voltage are 15 min and 8–9 kV, respectively. Meanwhile, the carbon atoms with unpaired electrons are found to be increased during the process of plasma treatment and used as active sites for chemical adsorption. Both OFGs and carbon atoms with unpaired electrons on the carbon surface play a vitally important role for water vapor adsorption. The surface functionalities and chemical adsorption may govern the adsorption–desorption behavior of water vapor at low relative humidity (RH less than 40%). Adsorption mechanism of water vapor on the carbon surface before and after LTOP treatment is proposed. After several adsorption and desorption cycles, the adsorption capacity of LTOP-treated ACFs is still higher than that of ACF-raw. Therefore, this technology may shed light on the potential application of LTOP-treated ACFs in harvesting water from air at low relative humidity.
Resistive random access memory (RRAM) based on ultrathin 2D materials is considered to be a very feasible solution for future data storage and neuromorphic computing technologies. However, ...controllability and stability are the problems that need to be solved for practical applications. Here, by introducing a damage‐less ion implantation technology using ultralow‐energy plasma, the transport mechanisms of space charge limited current and Schottky emission are successfully realized and controlled in RRAM based on 2D Bi2Se3 nanosheets. The memristors exhibit stable resistive switching behavior with a high resistive switching ratio (>104), excellent cycling endurances (300 cycles), and great retention performance (>104 s). The reliability and controllability of Bi2Se3 memory endowed by oxygen plasma injection demonstrate the great potential of this ultralow‐energy ion implantation technology in the application of 2D RRAM.
Highly controllable 2D resistive random access memory (RRAM) based on Bi2Se3 nanosheet is achieved by a damage‐less ion implantation technology using ultralow‐energy plasma. The transport mechanism, resistive switching mechanism, memory window, and working voltage in RRAM are successfully controlled by oxygen plasma injection. The memristors demonstrate excellent properties of high resistive switching ratio, outstanding cycling endurance, and retention performance.
Titanium (Ti) is widely used in dental implants; however, the bioinert surface has been shown to limit osseointegration, particularly in patients with poor bone quality. This study created a thin ...bioactive oxide film on Ti dental implants via oxygen plasma immersion ion implantation (OPIII) to improve bone cell differentiation and osseointegration. OPIII treatment was performed using low (1016 ions/cm2) and high (4 × 1017 ions/cm2) doses of oxygen ions. The Ti surfaces were characterized in terms of topography, wettability, chemical composition, and crystal structure. The differentiation of human bone marrow mesenchymal stem cells on OPIII-treated Ti surfaces was evaluated in vitro in terms of alkaline phosphatase (ALP) activity (early stage marker) and von Kossa staining (late stage marker). The osseointegration of OPIII-treated screw-type Ti dental implants in the femur of rabbits was evaluated in vivo using scanning electron microscope/backscattered electron imaging and histological staining at 4 weeks after implantation. OPIII treatment could induce a Ti oxide film on Ti surface without altering the surface topography, roughness or wettability. Higher oxygen ions dose increased the thickness of the surface Ti oxide film as well as the proportion of rutile phase titanium dioxide (TiO2) in the Ti oxide film. The OPIII-treated Ti surfaces presented higher ALP expression level, stronger von Kossa staining signal, and higher bone-to-implant contact. Note that all of these effects were more pronounced on surfaces created using higher oxygen ions dose due to the higher proportion of rutile phase TiO2. Overall, our results indicate that OPIII treatment using higher oxygen ions dose can enhance the in vitro bone cell differentiation and in vivo osseointegration of Ti dental implants.
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•Oxygen plasma immersion ion implantation (OPIII) created a Ti oxide film on Ti.•OPIII enhanced cell differentiation, in terms of ALP activity and von Kossa stain.•OPIII enhanced in vivo osseointegration, in terms of bone-to-implant contact.•Higher rutile TiO2 content in Ti oxide film enhanced better biological responses.•OPIII treatment has high potential in Ti dental implant applications.
The oxygen evolution reaction (OER) and the value‐added oxidation of renewable organic substrates are critical to supply electrons and protons for the synthesis of sustainable fuels. To meet ...industrial requirements, new methods for a simple, fast, environmental‐friendly and cheap synthesis of robust, self‐supported and high surface area electrodes are required. Herein, a novel in‐liquid plasma (plasma electrolysis) approach for the growth of hierarchical nanostructures on nickel foam is reported on. Under morphology retention, iron can be doped into this high surface area electrode. For the oxidation of 5‐(hydroxymethyl)furfural and benzyl alcohol, the iron‐free, plasma‐treated electrode is more suitable reaching current densities up to 800 mA cm−2 with Faradaic efficiencies above 95%. For the OER, the iron‐doped nickel foam electrode reaches the industrially relevant current density of 500 mA cm−2 at 1.473 ± 0.013 VRHE (60 °C) and shows no activity decrease over 140 h. The different effects of iron doping are rationalized using methanol probing and in situ Raman spectroscopy. Furthermore, the intrinsic activity is separated from the number of active sites, and, for the organic oxidation reactions, diffusion limitations are revealed. The authors anticipate that the plasma modified nickel foam will be suitable for various (electro)catalytic processes.
A novel in‐liquid plasma approach for the growth of hierarchical nanostructures (nickel‐(iron) oxyhydroxides (NiFeOOH)) on nickel foam leading to surface area and active site enhancement is reported. The obtained electrode is exceptional for the oxidation of water (oxygen evolution reaction) and organic species (5‐(hydroxymethyl)furfural and benzyl alcohol) at high current densities
The impact of O2 plasma treatment on novel amorphous oxide InWZnO (IWZO) as conductive bridge random access memory (CBRAM) was investigated. A high-quality film on the surface of IWZO can be obtained ...by using remote O2 plasma treatment. The uniformity of O2 plasma sample is better than control sample, and also the set and reset voltage are more uniform and smaller to suitable for memory operation. Moreover, the O2 plasma sample shows excellent memory performance, such as high switching endurance cycles (up to 3 × 103), long retention time for 104 s at 85 °C. These results show that the surface modification with O2 plasma on IWZO CBRAM device is a critical technique for next generation memory applications.
•Effect of oxygen plasma treatment on novel tungsten-doped InWZnO film were investigated.•The plasma-treated InWZnO film is used as resistive switching layer.•This is attributed to the formation of oxygen-rich layer on the InWZnO surface.
It has been a long-standing challenge to produce air-stable few- or monolayer samples of phosphorene because thin phosphorene films degrade rapidly in ambient conditions. Here we demonstrate a new ...highly controllable method for fabricating high quality, air-stable phosphorene films with a designated number of layers ranging from a few down to monolayer. Our approach involves the use of oxygen plasma dry etching to thin down thick-exfoliated phosphorene flakes, layer by layer with atomic precision. Moreover, in a stabilized phosphorene monolayer, we were able to precisely engineer defects for the first time, which led to efficient emission of photons at new frequencies in the near infrared at room temperature. In addition, we demonstrate the use of an electrostatic gate to tune the photon emission from the defects in a monolayer phosphorene. This could lead to new electronic and optoelectronic devices, such as electrically tunable, broadband near infrared lighting devices operating at room temperature.
Current graphene/metal composites are mostly limited to the cases of using graphene oxide (GO) which contains a high level of defects. In this work, the high-quality graphene nanoplatelets (GNPs) ...were used as starting graphene material to prepare the GNP/Cu composite. Oxygen plasma treatment was employed to conduct the surface functionalization of GNPs by grafting the considerable oxygen-functional groups but without noticeably damaging the graphene structure. It was found that the plasma-treated GNPs (P-GNPs) exhibited not only a good dispersability in ethanol/water, but also an enhanced electrostatic affinity with Cu powder, resulting in the P-GNP/Cu composite with a uniform GNP distribution and a good interfacial bonding. At 1 vol% GNP loading, the P-GNP/Cu composite presented a largely enhanced yield strength of 188 MPa with a relatively high failure elongation of 21%, significantly outperforming the composite with untreated GNPs (158 MPa, 12%). The enhanced strength could be explained by the load transfer mechanism and agreed approximately with the prediction of a modified shear-lag model. The good ductility was attributed to the prominent dislocation storage capability of P-GNP/Cu composite. Therefore, the oxygen plasma treatment provides a general and effective strategy to improve graphene distribution and mechanical properties of graphene/metal composites.
Fe-doped Ni (oxy)hydroxide shows intriguing activity toward oxygen evolution reaction (OER) in alkaline solution, yet it remains challenging to further boost its performance. In this work, a ...ferric/molybdate (Fe
/MoO
) co-doping strategy is reported to promote the OER activity of Ni oxyhydroxide. The reinforced Fe/Mo-doped Ni oxyhydroxide catalyst supported by nickel foam (p-NiFeMo/NF) is synthesized via a unique oxygen plasma etching-electrochemical doping route, in which precursor Ni(OH)
nanosheets are first etched by oxygen plasma to form defect-rich amorphous nanosheets, followed by electrochemical cycling to trigger simultaneously Fe
/MoO
co-doping and phase transition. This p-NiFeMo/NF catalyst requires an overpotential of only 274 mV to reach 100 mA cm
in alkaline media, exhibiting significantly enhanced OER activity compared to NiFe layered double hydroxide (LDH) catalyst and other analogs. Its activity does not fade even after 72 h uninterrupted operation. In situ Raman analysis reveals that the intercalation of MoO
is able to prevent the over-oxidation of NiOOH matrix from β to γ phase, thus keeping the Fe-doped NiOOH at the most active state.
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