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The growing demand for fossil-free energy has prompted extensive research into new, clean, and sustainable methods of meeting global energy needs. One promising approach is the production of green, sustainable fuels such as ammonia from base molecules like water and nitrogen using renewable electricity. Non-thermal atmospheric pressure plasma-based NH3 synthesis has been shown to have significant potential for the production of carbon-free fertilizer using renewable electricity. In this study, we developed an atmospheric pressure rotating gliding arc discharge reactor in conjunction with a catalyst to achieve a higher ammonia production rate. Our research involved a two-step ammonia production process, including the facile production of NOx and hydrogen from nitrogen discharge in water and the highly selective catalytic reduction of NOx to ammonia in the presence of hydrogen. The plasma technique we studied yielded an ammonia concentration of approximately 0.84% with a selectivity of 95% and a production rate of 120 µmol/s, by integrating a catalytic reduction system with plasma. These results are notable as they represent a 300-400-fold increase in ammonia yield compared to previous studies on ammonia synthesis from nitrogen. These promising findings represent a significant advancement in the transition towards sustainable and environmentally friendly ammonia production.

The presence of random arrays of elongated nanostructures with dimensional nonuniformity on the cuticular surfaces of insects endows them with antiwetting characteristics, as exemplified by nanopillar arrays on dragonfly wings and nanocone arrays on cicada wings. But the roles of the nanostructure shape and dimensional nonuniformity, as well as of the randomness of placement, on antiwetting characteristics are difficult to delineate because of the different chemical compositions of the surfaces of dragonfly and cicada wings. Therefore, biomimetic random arrays of nanopillars and nanocones with a similar tip diameter, placement irregularity, and chemical composition were fabricated on polypropylene substrates by plasma etching and polymerization. Gaussian nonuniformity of the nanopillar/nanocone dimensions as well as the irregularity of their placement were considered in determining the antiwetting capillary pressure and the adhesion energy. The gradient of the antiwetting capillary pressure normal to the substrate plane is the reason for nanocone arrays to resist wetting by water droplets impacting at high speeds much better than nanopillar arrays. The tapered shape of nanocones also promotes the dewetting transition of droplets from the sticky Wenzel state to the slippery Cassie state.

A novel two-dimensional (2D) carbon material composed of decagonal pores, and hexagonal and quadrilateral carbon rings (DHQ-graphene) is predicted by first-principles calculations. The results show that this metastable phase material displays anisotropic mechanical properties, and its in-plane Young's modulus is comparable with that of penta-graphene. DHQ-graphene is a metallic carbon material with a much higher electronic density of states of around 0.193 eV per states per atom. Equally importantly, it is also found that the most favorable adsorption site is the bridge site in the edge shared by the six- and ten-membered rings of DHQ-graphene, which has a stronger adsorption energy for oxygen (−0.27 eV) with dispersion correction (DFT-D3). The charge transfer from a DHQ-graphene sheet to an O atom amounts to 0.834|e|, 3.35% higher than that of perfect graphene. This implies that DHQ-graphene should have a good ability to adsorb oxygen with an easily controlled adsorption structure. Interestingly, it may conceivably be synthesized by a bottom-up approach from the carbon skeleton of naphthalene (C10H8). In addition, a 3D stacked structure of this material has also been investigated. This work provides a novel strategy for constructing a corrosion-resistant material by designing a 2D structure based on high-order carbon rings.

Octafluorocyclobutane and acrylic acid (C4F8-co-AA) are plasma copolymerized onto low-density polyethylene (LDPE) and glass slides under various pulsation periods of radio frequency pulsed plasma. The surface wettability of plasma polymer coating is traditionally considered as a substrate-independent property. The combined effect of ultrathin C4F8-co-AA coatings and LDPE substrate on surface wettability is presented. The high concentration of the carboxylic acid functional groups gives rise to hydrophilicity via lowering duty cycle, and substrate impact gives rise to hydrophobicity for ultrathin coatings. The X-ray photoelectron spectroscopy and coating thickness measurements confirmed that the sudden increase in water contact angle for the lower duty cycle is influenced by the hydrophobic substrate for ultrathin polymer coatings. It is highlighted that the precise control over the surface wettability is attained by tuning the plasma parameters. The substrate-dependent wettability for flat substrate persisted for longer than 8 weeks, which demonstrates wetting stability for ultrathin coatings.

In this study, a sustainable air plasma-based nitrogen fixation into reactive nitrogen species in water (e.g. nitrate and nitrite) is presented, which mimics the lightning-based nitrogen fixation that occurs in nature. We report a hybrid plasma system that combines a dielectric barrier discharge (DBD) reactor (as an efficient ozone source) and an arc plasma reactor (as an efficient NOx source). This hybrid plasma system completely converts gaseous NOx and O-3 into NOx- in water with almost zero emissions (NOx and O-3). Gaseous outlets, in-liquid species, and electrical parameters were investigated. The energy cost for nitrate production via a single-pass reaction was extremely reduced to 8 MJ mol(-1), which enhanced the applicability of the direct one-step nitrogen fixation into NOx- in water for distributed fertilizer production to decrease the dependence on the Haber-Bosh process toward sustainable agricultural development.

Octafluorocyclobutane and acrylic acid (C4F8-co-AA) plasma copolymer coatings are deposited using a pulsed wave (PW) radio frequency (RF) plasma on low density polyethylene (LDPE). The influence of duty cycle in pulsed process with the monomer feed rate on the surface chemistry and wettability of C4F8-co-AA plasma polymer coatings is studied. The concentration of the carboxylic acid (hydrophilic) groups increase, and that of fluorocarbon (hydrophobic) groups decrease by lowering the duty cycle. The combined effect of surface chemistry and surface morphology of the RF pulsed plasma copolymer coatings causes tunable surface wettability and surface adhesion. The gradual emergence of hydrophilic contents leads to surface heterogeneity by lowering duty cycle causing an increased surface adhesion in hydrophobic coatings. The C4F8-co-AA plasma polymer coatings on the nanotextured surfaces are tuned from repulsive superhydrophobicity to adhesive superhydrophobicity, and further to superhydrophilicity by adjusting the duty cycles with the monomer feed rates. (C) 2017 Elsevier B.V. All rights reserved.

Inspired by the antireflection and antiwetting functionalities of dragonfly wings decorated with random nanopillars and a wax layer, a facile technique to endow the same functionalities has been devised. In this two-step plasma nanotexturing technique, first oxygen plasma treatment is implemented to grow the random nanopillars on the polymethyl methacrylate (PMMA) surfaces, and then C(4)F(8)plasma polymer deposition is carried out so that the thin fluorocarbon film with a low surface free energy and refraction index covers the random nanopillars. The biomimetic PMMA surfaces exhibit excellent broadband and omnidirectional antireflection properties and robust antiwetting properties under the water droplet impact. The superhydrophobicity at the slippery Cassie state was maintained under the natural oscillation of residual droplets.

Muzammil Iqbal et al. have shown the promising prospects for the plasma copolymerization technique of fabricating smart surfaces with tunable wettability and reversibly switchable pH-responsiveness. The polymer structures can be engineered to tune wetting states at extremes – from superhydrophobic state to superhydrophilic state. A simple plasma polymerization method was used for the preparation of smart copolymer coatings with tunable and reversibly-switchable wetting properties in various pH environments. The wide-range and tunable wetting properties by coordination of composition, functionality, and morphology using straightforward protocol open up a potential door for the fabrication of multifunctional smart coatings. Concluded: the possible wettability range is broad, and the protocol to tune wettability and chemical structure is straightforward, so this methodology opens up a potential door for the fabrication of smart surfaces.

Novel and intelligent plasma copolymers based on hydrophilic/hydrophobic monomers with tunable wettability and pH-responsiveness are demonstrated. A series of plasma copolymer coatings with various carboxylic acid and fluorocarbon group ratio are prepared on the low-density polyethylene (LDPE) surfaces via capacitively coupled radio frequency plasma (CCP). The static water contact angles (SWCA) of C4F8-co-AA plasma polymer coatings on nanotextured LDPE surfaces tuned from 163 to 4 degrees. These C4F8-co-AA plasma polymer coatings showed different pH-responsiveness by the combined effect of the carboxylic acid to fluorocarbon group ratios and surface nanotexture. The increase of carboxylic acid groups of C4F8-co-AA plasma polymers shifted the reversibly switchable wettability of pH-responsiveness towards low SWCA range. The magnifying effect of surface nanotexture on pH-responsiveness was also observed.

Plasma-assisted nitrogen fixation is a promising sustainable and clean alternative to the classical Haber–Bosch process. However, the high energy consumption and low production rate of plasma-assisted nitrogen fixation limit its application. This study shows that the non-thermal (non-equilibrium) enhancement of the arc plasma significantly reduces the energy consumption of nitrogen fixation. The highest energy efficiency with high NO selectivity is observed with a low specific energy input (SEI). However, the highest production rate is reached at a high SEI. The studied process offers high NO selectivity (up to 95%) with low energy consumption (∼48 GJ per tN) at 0.1 kJ L−1 SEI, which is much lower than the previously reported value of plasma-assisted atmospheric nitrogen fixation and is close to that of the Haber–Bosch process.