Two-Dimensional Materials for Highly Efficient and Stable Perovskite Solar Cells.

Perovskite solar cells (PSCs) offer low costs and high power conversion efficiency. However, the lack of long-term stability, primarily stemming from the interfacial defects and the susceptible metal electrodes, hinders their practical application. In the past few years, two-dimensional (2D) materials (e.g., graphene and its derivatives, transitional metal dichalcogenides, MXenes, and black phosphorus) have been identified as a promising solution to solving these problems because of their dangling bond-free surfaces, layer-dependent electronic band structures, tunable functional groups, and inherent compactness. Here, recent progress of 2D material toward efficient and stable PSCs is summarized, including its role as both interface materials and electrodes. We discuss their beneficial effects on perovskite growth, energy level alignment, defect passivation, as well as blocking external stimulus. In particular, the unique properties of 2D materials to form van der Waals heterojunction at the bottom interface are emphasized. Finally, perspectives on the further development of PSCs using 2D materials are provided, such as designing high-quality van der Waals heterojunction, enhancing the uniformity and coverage of 2D nanosheets, and developing new 2D materials-based electrodes.

Enhancing the electrochemical properties of a lithium-sulfur battery using a modified separator with a phase-inversion layer.

The commercial application of lithium-sulfur (Li-S) batteries is limited by the inherent defects of poor conductivity of sulfur and the shuttling effect of polysulfides. To overcome these limitations, a modified layer comprising a porous network PVDF-PMMA skeleton and Ketjen black (KB) carbon nanoparticles was coated on the polyethylene (PE) separator using the phase inversion method. The PVDF-PMMA-KB (PPK) composite layer with a structure abundant in mesopores can effectively limit the shuttling effect of polysulfides via a physical barrier and adsorption. Moreover, the utilization of active substances substantially increased as the KB carbon nanoparticles could provide additional reaction sites for activating inactive polysulfides and depositing lithium sulfide. The electrochemical properties of the Li-S battery were considerably enhanced using the modified separator with a PPK layer, which was reflected in the higher rate capability and longer cycling life. The cell with a modified separator delivered a specific capacity of 723 mA h g-1 at 1 C, and the capacity retention reached 73.3% after 400 cycles with a low decay rate of 0.223% per cycle. This work provides a novel preparation method for a modified layer on the separator and promotes the large-scale application of Li-S batteries.

Hybrid Membrane Composed of Nickel Diselenide Nanosheets with Carbon Nanotubes for Catalytic Conversion of Polysulfides in Lithium-Sulfur Batteries.

Lithium-sulfur batteries demonstrate enormous energy density are promising forms of energy storage. Unfortunately, the slow redox kinetics and polysulfides shuttle effect are some of the factors that prevent the its development. To address these issues, the hybrid membrane with combination of nickel diselenide nanosheets modified carbon nanotubes (NSN@CNTs) and utilized Li2 S6 catholyte for lithium sulfur battery. The conductive CNTs facilitates fast electronic/ionic transport, while the polarity of NSN as a strong affinity to lithium polysulfides, effectively anchoring them, facilitating the redox conversion of polysulfide species, and effectively diminishing reaction barriers. The cell with NSN@CNTs delivers the first discharge capacity of 1123.8 mAh g-1 and maintains 786.5 mAh g-1 after 300 cycles (0.2 C) at the sulfur loading 5.4 mg. Its rate capability is commendable, enabling it to sustain a capacity of 559.8 mAh g-1 even at a high discharge rate of 2 C. In addition, its initial discharge capacity can remain 8.33 mAh even at 10.8 mg for duration of 100 cycles. This research indicates the potential application of NSN@CNTs hybrid materials in lithium-sulfur batteries.

Suppressing Optical Losses in Solar Cells via Multifunctional and Large-Scale Geometric Arrays.

The occurrence of optical loss on the surface of solar cells is inevitable due to the difference in the refractive index between air and glass, as well as the insufficient absorption of the active layer. To address this challenge, micron-sized geometry arrays, such as hemispheres and hemisphere pits, are prepared on quartz glass through the advanced indirect patterning technology of UV-LIGA. These geometric arrays exhibit multiple mechanisms for controlling light waves, including multiple rebounds, diffraction scattering, and total internal reflection. These synergistic effects suppress optical losses at the device's surface and prolong the photon propagation path in the active layer. After being patterned with this structure, the average transmittance and haze of the quartz glass reach 93.91% and 75%, respectively. Compared to their flat counterpart, the decorated monocrystalline silicon solar cells demonstrated an apparent improvement in photocurrent and produced a 7.2% enhancement in power conversion efficiency.

An In-Situ Formed Tunneling Layer Enriches the Options of Anode for Efficient and Stable Regular Perovskite Solar Cells.

Perovskite solar cells (PSCs) are taking steps to commercialization. However, the halogen-reactive anode with high cost becomes a stumbling block. Here, the halogen migration in PSCs is utilized to in situ generate a uniform tunneling layer between the hole transport materials and anodes, which enriches the options of anodes by breaking the Schottky barrier, enabling the regular PSCs with both high efficiency and stability. Specifically, the regular PSC that uses silver iodide as the tunneling layer and copper as the anode obtains a champion power conversion efficiency of 23.24% (certified 22.74%) with an aperture area of 1.04 cm2. The devices are stable, maintaining 98.6% of the initial efficiency after 500 h of operation at the maximum power point with continuous 1 sun illumination. PSCs with different tunneling layers and anodes are fabricated, which confirm the generality of the strategy.

Recent advances in transition metal nitrides for hydrogen electrocatalysis in alkaline media: From catalyst design to application.

Hydrogen (H2) has been considered an ideal alternative energy source for solving energy supply security and greenhouse gas reduction. Although platinum group metal (PGM) catalysts have excellent performance in hydrogen electrocatalysis, their scarcity and high cost limit their industrial application. Therefore, it is necessary to develop low-cost and efficient non-PGM catalysts. Transition metal nitrides (TMNs) have attracted much attention because of their excellent catalytic performance in hydrogen electrochemistry, including hydrogen evolution reaction (HER)/hydrogen oxidation reaction (HOR). In this paper, we review and discuss the mechanism of HER/HOR in alkaline media. We compare and evaluate electrocatalytic performance for the HER/HOR TMN catalysts recently reported. Finally, we propose the prospects and research trends in sustainable alkaline hydrogen electrocatalysis.

Study of the Cu(111) Surface by Scanning Tunneling Microscopy: The Morphology Evolution, Reconstructions, Superstructures and Line Defects.

The Cu(111) surface is an important substrate for catalysis and the growth of 2D materials, but a comprehensive understanding of the preparation and formation of well-ordered and atomically clean Cu(111) surfaces is still lacking. In this work, the morphology and structure changes of the Cu(111) surface after treatment by ion bombardment and annealing with a temperature range of 300-720 °C are investigated systematically by using in situ low-temperature scanning tunneling microscopy. With the increase of annealing temperature, the surface morphology changes from corrugation to straight edge, the number of screw dislocations changes from none to numerous, and the surface atomic structure changes from disordered to ordered structures (with many reconstructions). In addition, the changing trend of step width and step height in different stages is different (first increased and then decreased). A perfect Cu(111) surface with a step height of one atom layer (0.21 nm) and a width of more than 150 nm was obtained. In addition, two interesting superstructures and a new surface phase with a large number of line defects were found. This work serves as a strong foundation for understanding the properties of Cu(111) surface, and it also provides important guidance for the effective pretreatment of Cu(111) substrates, which are widely used.

A Multifunctional Gradient Solid Electrolyte Remarkably Improving Interface Compatibility and Ion Transport in Solid-State Lithium Battery.

Solid electrolytes with both interface compatibility and efficient ion transport have been an urgent technical requirement for the practical application of solid-state lithium batteries. Herein, a multifuctional poly(1,3-dioxolane) (PDOL) electrolyte combining the gradient structure from the solid state to the gel state with the Li6.4La3Zr1.4Ta0.6O12 (LLZTO) interfacial modification layer was designed, in which the "solid-to-gel" gradient structure greatly improved the electrode/electrolyte interface compatibility and ion transport, while the solid PDOL and LLZTO layers effectively improved the interface stability of the electrolyte/lithium anode and the inhibition of the lithium dendrites via their high mechanical strength and forming a stable interfacial SEI composite film. This gradient PDOL/LLZTO composite electrolyte possesses a high ionic conductivity of 2.9 × 10-4 S/cm with a wide electrochemical window up to 4.9 V vs Li/Li+. Compared with the pristine PDOL electrolyte and PDOL solid electrolyte membrane coated with a layer of LLZTO, the gradient PDOL/LLZTO composite electrolyte shows better electrode/electrolyte interfacial compatibility, lower interface impedance, and smaller polarization, resulting in enhanced rate and cycle performances. The NCM622/PDOL-LLZTO/Li battery can be stably cycled 200 times at 0.3C and 25 °C. This multifunctional gradient structure design will promote the development of high-performance solid electrolytes and is expected to be widely used in solid-state lithium batteries.

Integrating high ionic conductive PDOL solid/gel composite electrolyte for enhancement of interface combination and lithium dentrite inhibition of solid-state lithium battery.

High interface impedance, slow ion transmission, and easy growth of lithium dendrites in solid-state lithium battery are main obstacles to its development and application. Good interface combination and compatibility between electrolyte and electrodes is an important way to solve these problems. In this work, we successfully combined a high ionic conductive polymerized 1,3-dioxolane (PDOL) solid-state electrolyte and a PDOL gel-state electrolyte to form a rigid-flexible composite structural electrolyte and realized the gelation modification of solid electrolyte/electrode interface. This "PDOL SE + PDOL Gel" composite structure not only improves the electrode/electrolyte interfacial contact, reduces the interfacial impedance, but also inhibits the growth of lithium dendrites in the interface between lithium anode and electrolyte by forming an uniform Li-Zr-O and LiF composite protection layer. This composite electrolyte has high ionic conductivity of 5.96 × 10-4 S/cm and wide electrochemical stability window of 5.0 V. The Li/PDOL SE + PDOL Gel/Li cells can be cycled stably for nearly 400 h at a current density of 1.0 mA/cm2. The assembled LiCoO2/PDOL SE + PDOL Gel/Li cells can be cycled for 250 cycles at 0.5 C with a capacity retention of 80%. This PDOL solid/gel composite electrolyte shows high promising commercial application prospect due to its high security performance, excellent interfacial properties and dendrite inhibition ability.

Porous N-doped carbon nanofibers assembled with nickel ferrite nanoparticles as efficient chemical anchors and polysulfide conversion catalyst for lithium-sulfur batteries.

Lithium-sulfur (Li-S) batteries are deemed to have great prospects in the next generation advanced energy storage systems and have been considered in recent years. However, the majority of substrates with both high electronic conductivity and full coverage of adsorption-catalysis synergy are difficult to achieve. Herein, nitrogen functionalized porous carbon nanofibers assembled with nickel ferrite nanoparticles (NFO/NCFs) are successfully prepared by electrospinning combined with hydrothermal treatment, which were applied to current collector containing Li2S6 catholyte and binder-free for Li-S batteries. With its abundant active sites, the NFO/NCFs have a vital role in the adsorption and catalysis of the polysulfides, which further accelerate the redox kinetics. Consequently, Li2S6 catholyte impregnated NFO/NCFs electrode (sulfur loading: 5.09 mg cm-2) exhibits the first discharge capacity of 997 mAh g-1 and maintains at 637 mAh g-1 after 350 cycles at 0.2C, which is superior cycling performance than NCFs. Even at 10.2 mg cm-2 sulfur loading, the composite electrode shows a high area capacity of 8.35 mAh cm-2 at 0.1C and retains 6.01 mAh cm-2 after 150 cycles. The results suggest the multifunction NFO/NCFs that anchor effectively and catalysis are beneficial to realize the goal of the large-scale application for Li-S batteries.

Enhanced ionic conductivity and lithium dendrite suppression of polymer solid electrolytes by alumina nanorods and interfacial graphite modification.

Poor room-temperature ionic conductivity and lithium dendrite formation are the main issues of solid electrolytes. In this work, rod-shaped alumina incorporation and graphite coating were simultaneously applied to poly (propylene carbonate) (PPC)-based polymer solid electrolytes (Wang et al., 2018). The obtained alumina modified solid electrolyte membrane (Al-SE) achieves a high ionic conductivity of 3.48 × 10-4 S/cm at room temperature with a wide electrochemical window of 4.6 V. The assembled NCM622/Al-SE/Li solid-state battery exhibits initial discharge capacities of 198.2 mAh/g and 177.5 mAh/g at the current density of 0.1 C and 0.5 C, with the remaining capacities of 165.8 mAh/g and 161.3 mAh/g after 100 cycles respectively. The rod-shaped structure of Al2O3 provides fast transport channels for lithium ions and its Lewis acidity promotes the dissociation of lithium salts and release of free lithium ions. The lithiophilic Al2O3 and Graphite form intimate contact with metallic Li and create fast Li+ conductive layers of Li-Al-O layer and LiC6 layer, thus facilitating the uniform deposition of Li and inhibiting Li dendrite formation during long-term cycling. This kind of composite Al-SE is expected to provide a promising alternative for practical application in solid electrolytes.

Transcatheter Closure of Large Coronary-Cameral Fistulas Using the Patent Ductus Arteriosus Occluder or Amplatzer Vascular Plugs.

Transcatheter closure (TCC) has emerged as the first-line treatment for coronary artery fistulas. However, limited data exist regarding the long-term outcomes and technical aspects of this procedure. We aimed to report the long-term outcomes and technical aspects of TCC of large coronary-cameral fistulas (CCFs).All patients with large CCFs who underwent attempted TCC using the patent ductus arteriosus (PDA) occluder or Amplatzer vascular plug (AVP), from June 2002 to December 2017, were retrospectively reviewed. A total of 23 patients with large CCFs underwent attempted TCC using the PDA occluder or AVP. Most CCFs originated from the right coronary artery and drained predominantly into the right heart chamber. Procedural success was achieved in 21 (91.3%) patients. Devices were deployed using the arteriovenous loop in 15, transarterial approach in 4, and arterio-artery loop approach in 2 patients. Procedural complications included coronary spasm in one and side branch occlusion in one patient. Among these 21 patients with successful device implantation, follow-up angiograms or computed tomography angiograms were obtained in 14 (66.7%) patients at a median of 11.0 (range, 9.8-16.3) months. Late complications included thrombosis of residual fistula segment without myocardial infarction (MI) in one, coronary thrombosis resulting in MI in one, and recanalization necessitating re-intervention in one patient. No death and device embolization occurred.TCC of large CCFs using the PDA occluder or AVP is an effective therapy in anatomically suitable candidates, with favorable long-term outcomes. Given that potentially hazardous complications may occur late after the procedure, long-term periodic evaluation is mandatory.

Improved Interface Stability and Room-Temperature Performance of Solid-State Lithium Batteries by Integrating Cathode/Electrolyte and Graphite Coating.

Poor interface stability is a crucial problem hindering the electrochemical performance of solid-state lithium batteries. In this work, a novel approach for interface stability was proposed to integrate the cathode/solid electrolyte by forming an electrolyte buffer layer on the rough surface of the cathode and coating a layer of graphite on the side of the electrolyte facing the lithium anode. This hybrid structure significantly improves the integration and the interface stability of the electrode/electrolyte. The interfacial resistance was dramatically reduced, the stability of the plating/stripping of Li metal was enhanced, and the growth of lithium dendrites was also inhibited due to the formation of the LiC6 transition layer. The obtained solid-state lithium battery shows enhanced rate performance at room temperature from 0.5 to 4 C and stable cycling performance at 1 C with a retention capacity of 100 mAh g-1 after 200 cycles. This integrated electrode/electrolyte design approach is expected to be widely used to improve interfacial stability and room-temperature electrochemical performance of solid-state batteries.

Electrochemical Behaviors of Sulfurized-Polyacrylonitrile with Synthesized Polyacrylonitrile Precursors Based on the Radical Polymerization Through Monomer Acrylonitrile.

Polyacrylonitrile (PAN) precursors have been polymerized at different radical polymerization temperatures for preparing sulfurized-polyacrylonitrile (S-PAN) composite cathodes in rechargeable lithium sulfur battery. The physical properties of these composites have been investigated using X-ray diffraction, Fourier transform infrared spectrometry, Raman spectroscopy, Brunner-Emmet-Teller measurement and Gel permeation chromatography analysis. The electrochemical performance of the S-PAN composite cathodes made from the PAN precursor was investigated. The results showed that the molecular weight distribution of the PAN precursors affected the electrochemical performance of the S-PAN made from the PAN precursor. S-PAN composites derived from PAN with a narrower molecular weight distribution at 65 °C were exhibit the best electrochemical performance in lithium-sulfur battery.

A novel all-fiber-based LiFePO4/Li4Ti5O12 battery with self-standing nanofiber membrane electrodes.

Electrodes with high conductivity and flexibility are crucial to the development of flexible lithium-ion batteries. In this study, three-dimensional (3D) LiFePO4 and Li4Ti5O12 fiber membrane materials were prepared through electrospinning and directly used as self-standing electrodes for lithium-ion batteries. The structure and morphology of the fibers, and the electrochemical performance of the electrodes and the full battery were characterized. The results show that the LiFePO4 and Li4Ti5O12 fiber membrane electrodes exhibit good rate and cycle performance. In particular, the all-fiber-based gel-state battery composed of LiFePO4 and Li4Ti5O12 fiber membrane electrodes can be charged/discharged for 800 cycles at 1C with a retention capacity of more than 100 mAh·g-1 and a coulombic efficiency close to 100%. The good electrochemical performance is attributed to the high electronic and ionic conductivity provided by the 3D network structure of the self-standing electrodes. This design and preparation method for all-fiber-based lithium-ion batteries provides a novel strategy for the development of high-performance flexible batteries.

An Overlapped Nano-Fe2O3/TiO2 Composite Coating on Activated Carbon Fiber Membrane with Enhanced Photocatalytic Performance.

Treatment of high concentration organic wastewater has always been a difficult problem in the field of water purification due to its high cost, low efficiency, long processing cycle and possible second pollution. An overlapped nano-Fe2O3/TiO2@activated carbon fiber membrane composite was successfully prepared by hydrothermal loading method. Nano-rod-like TiO2 and columnar Fe2O3 polyhedrals overlapped and formed a composite coating on the surface of activated carbon fiber membrane. This composite can absorb visible light and successfully remove the high concentration Congo red pollutant (400 mg/L) in 24 h. The enhanced photocatalytic performance should be attributed to the synergistic reaction of nano-Fe2O3 and nano-TiO2, which improves the separation of photo-generated electrons and holes thus enhances the photocatalytic efficiency. This multifunctional fiber membrane is expected to be widely applied in various organic wastewater treatments.

Enhanced Electrochemical Performance of Simple Electrospun Non-Woven Nickel/Carbon Nanofibers as a Functional Interlayer for Lithium-Sulfur Batteries.

Non-woven nickel/carbon nanofibers (NW(Ni/C)NFs) are developed using a facile one-pot electrospinning method as a functional interlayer for rechargeable lithium-sulfur (Li-S) batteries. The functional interlayer of NW(Ni/C)NFs is sandwiched between a sulfur cathode and the separator and acts as a shuttle inhibitor to sulfur and polysulfides. Because of the sandwiched structure and the nickel additive, the Li-S cell shows better performance in terms of capacity utilization and reversibility. When the NW(Ni/C)NFs were calcined at 900 °C with 1 g of nickel salt additive, the discharge capacity of the cells was the best, and the initial discharge capacity was 1062 mAh g-1. With 200 charge-discharge cycles at 1 C, the discharge capacity of the cells remained above 910 mAh g-1, which is about 85.7% of its initial capacity. The improvement to the cells' electrochemical performance is attributed to the 3D architecture of the NW(Ni/C)NFs as a functional interlayer and to the appropriate amount of nickel addition. This provides a good conductive network with structural stability and the migrating polysulfide reduces the "shuttling phenomenon" during the charge-discharge processes.

Immobilisation of sulphur on cathodes of lithium-sulphur batteries via B-doped atomic-layer carbon materials.

Developing new host materials for cathodes and exploring their binding mechanisms in lithium-sulphur batteries are crucial issues since the present host materials exhibit low sulphur entrapment properties, thus resulting in the rapid decay of overall performance. In this work, we systematically investigated B-doped atomic-layer carbon materials as the cathode hosts of lithium-sulphur batteries via density functional theory calculations. Based on the analysis of optimised molecular structures, binding energies and surface charge densities, we found that B-doping can help materials suppress the dissolution of sulphides during cycles, further improving the performance of lithium-sulphur batteries. Additionally, we concluded that the internal interactions among multiple Li2Sn-adsorbed structures facilitate the capture of Li2Sn. Furthermore, we found that B-doped graphdiyne is a promising host material since it exhibits a stronger attraction to Li2Sn than other selected materials and an outstanding sulphur loading of ∼70 wt%.

Patent ductus arteriosus coexisting with a left brachiocephalic artery originating from the descending aorta: A case report.

RATIONAL: Patent ductus arteriosus (PDA) and a coexisting left brachiocephalic artery originating from the descending aorta is an extremely rare anomaly of unknown etiology. PATIENT CONCERNS: Herein we report a 3-year-old female who was found to have this condition during intervention process to close PDA. DIAGNOSIS: The patient was diagnosed with PDA coexisting with left brachiocephalic artery through angiography. INTERVENTION: Intervention involved transcatheter closure of the pulmonary side of PDA with coils. OUTCOMES: At 6-months follow up, the patient was well, with no symptoms and normal flow through the left carotid artery. LESSONS: PDA coexisting with left brachiocephalic artery originating from the descending aorta is a very rare anomaly. When this variety of PDA is closed, it is important to avoid affecting the blood flow in the left brachiocephalic trunk. For this reason, closure on the side of the pulmonary artery may be the best solution.