Effect of the Al/AlOx interfacial stacking sequence on the transport properties of alumina tunnel junctions.

Superconducting quantum bits based on Al/AlOx/Al Josephson junction devices are among the most developed quantum bits at present. The microstructure of the device interface critically affects the electrical properties of Josephson junctions, which in turn severely affects the superconducting quantum bits. Further progress towards scalable superconducting qubits urgently needs to be guided by novel analysis mechanisms or methods to improve the performance of junctions. A direct experimental study of the atomic structure of the device is very challenging. Therefore, we simulated three-dimensional Al/α-Al2O3/Al Josephson junction devices via first-principles electronic structure and ballistic transport calculations to investigate the relationship between transport properties and the Al/Al2O3 stacking sequence. This work elucidates in detail the effects of the aluminum and alumina stacking sequence on the electron transport properties of the Al/Al2O3/Al system at the microscopic level by combining first-principles density functional theory and a non-equilibrium Green's function formalism. It is first revealed that the oxygen termination mode exhibits the least sensitivity to conductance changes in the Al/Al2O3 stacking sequence, offering useful theoretical guidance for increasing the yield of fixed-frequency multi-qubit quantum chips which require tight control on qubit frequency.

O-terminated interface for thickness-insensitive transport properties of aluminum oxide Josephson junctions.

Alumina Josephson junction has demonstrated a tremendous potential to realize superconducting qubits. Further progress towards scalable superconducting qubits urgently needs to be guided by novel analysis mechanisms or methods to reduce the thickness sensitivity of the junction critical current to the tunnel barrier. Here, it is first revealed that the termination mode of AlOx interface plays a crucial role in the uniformity of critical current, and we demonstrate that the O-terminated interface has the lowest resistance sensitivity to thickness. More impressively, we developed atomically structured three-dimensional models and calculated their transport properties using a combination of quantum ballistic transport theory with first-principles DFT and NEGF to examine the effects of the Al2O3 termination mode and thickness variations. This work clarifies that O-terminated interface can effectively improve the resistance uniformity of Josephson junction, offering useful guidance for increasing the yield of fixed-frequency multi-qubit quantum chips which require tight control on qubit frequency.

Facile Fabrication of Slippery Lubricant-Infused CuO-Coated Surfaces with Different Morphologies for Efficient Water Collection and Excellent Slippery Stability.

How to prepare multifunctional surfaces with high nucleation density and fast droplet removal during droplet condensation remains a challenge. It is believed that a water droplet on a superhydrophobic surface (SHS) in the Cassie state is inclined to convert to the Wenzel state under high-pressure or high-humidity conditions, which results in the pinning effect. Hence, it is necessary to form thermodynamically stable lubricant-infused surfaces (LISs) to be applied in water condensation, especially under extreme working conditions. In this work, CuO LISs with two different morphologies (chrysanthemum-like and dandelion-like structures) in the slippery state were prepared and the effect of surface morphology on water harvesting behavior was investigated. The results indicated that dandelion-like CuO consisting of nanoneedles exhibited inferior water harvesting behavior compared to chrysanthemum-like CuO consisting of nanolamellas due to worse lubricating oil loss. Furthermore, the strong intermolecular forces between the perfluoropolyether (PFPE) lubricating oil and perfluorodecanethiol (PFDT)-modified coating resulted in a durable lubricating layer, which exhibited favorable anti-icing, anticorrosion, and liquid repellency even under strong acid and alkali conditions, high shear force rate up to 7000 rpm, and long-time ultraviolet light irradiation for 12 h. This work paves the path for efficient droplet nucleation and removal, which has potential in water harvesting in arid regions and water condensation for power generation.

Hybrid Hydrophilic-Hydrophobic CuO@TiO2-Coated Copper Mesh for Efficient Water Harvesting.

Fresh water scarcity has been a worldwide problem to be solved urgently. Inspired by the outstanding hydrophobic-hydrophilic patterns on the back of Namib desert beetles, hierarchical CuO@TiO2-coated surface with alternating hydrophilic-hydrophobic chemistry patterns were fabricated utilizing the photocatalysis of titanium dioxide through ultraviolet irradiation. The results indicated that the as-prepared hybrid dual-coated copper mesh enhanced the fog-collection efficiency compared with the uniformly superhydrophobic or superhydrophilic surface. This enhancement can be regulated by controlling the deposition cycle times of TiO2 multilayers on CuO and UV irradiation time. The best water harvesting behavior was determined at the deposition cycle times of 10 times and UV irradiation time of 4 h. This work findings offer new insights into the fabrication of hybrid hydrophilic-hydrophobic surfaces for highly efficient water harvesting.

Surface topographies of biomimetic superamphiphobic materials: design criteria, fabrication and performance.

Superamphiphobicity is a wetting phenomenon that not only water but also oils or organic solvents with low surface tension exhibit large contact angles above 150° along with low contact angle hysteresis on solid surface. It is well known that both chemical constituent and surface roughness have impacts on the wettability of solid surface. Herein, several fundamental wetting states and design criteria for re-entrant structures are introduced first. Then, various chemical modification materials endowing solid substrates low surface energy are summarized subsequently. Furthermore, roughening processes conferring hierarchical or re-entrant topographic structures on surfaces are classified based on different types of topographies abstracted from the natural oil-repellent creatures (mushroom-like structures) as well as bio-inspired superamphiphobic surfaces (i.e., randomly distributed nanostructures, regularly patterned microstructures and other complex hierarchical structures). Significantly, the impalement pressure and formulated rules of various re-entrant profiles are recommended in detail. At the same time, fabrication, outstanding performances such as mechanical durability, chemical stability are also mentioned according to different types of morphologies. Beyond that, current fabrication obstacles and future prospects are proposed simultaneously in the end.

Superhydrophobic Plant Leaves: The Variation in Surface Morphologies and Wettability during the Vegetation Period.

In this paper, for the first time, the surface wettability of cloverleaves and lotus leaves with specific surface structures at different growth stages is investigated. It is found that the clover exhibits water-repellent property similar to lotus leaves. Furthermore, the alternation in wettability of cloverleaves and lotus leaves during the whole vegetation period is investigated. The water contact angles and surface morphology of the leaves are measured by means of contact angle measurements and scanning electron microscopy, respectively. The chemical composition of plant leaves is analyzed utilizing Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. It is found that the wettability heavily depends on the surface structures during their growth and aging procedure, which enlightens us to design and fabricate biomimetic multifunctional superhydrophobic surfaces inspired by nature.

A robust and stretchable superhydrophobic PDMS/PVDF@KNFs membrane for oil/water separation and flame retardancy.

The wide application of superhydrophobic membranes has been limited due to their complicated preparation technology and weak durability. Inspired by the mechanical flexibility of nanofibrous biomaterials, nanofibrils have been successfully generated from Kevlar, which is one of the strongest synthetic fibers, by appropriate hydrothermal treatment. In this study, a robust superhydrophobic PDMS/PVDF@KNFs membrane is prepared via a simple one-step process and subsequent curing without combination with inorganic fillers. The as-prepared PDMS/PVDF@KNFs membrane not only shows efficient oil/water separation ability and oil absorption capacity but also has excellent superhydrophobicity stability after deformation. The resultant membrane shows stretchability, flexibility and flame retardance because of the reinforcing effect and the excellent flame retardancy of Kevlar. We believe that this simple fabrication of PDMS/PVDF@KNFs has promising applications in filtering membranes and wearable devices.