Hematite Hollow-Sphere-Array Photoanodes for Efficient Photoelectrochemical Water Splitting.

Constructing 3D nanophotonic structures is regarded as an effective method to realize efficient solar-to-hydrogen conversion. These photonic structures can enhance the absorbance of photoelectrodes by the light trapping effect, promote the charge separation by designable charge transport pathway and provide a high specific surface area for catalytic reaction. However, most 3D structures reported so far mainly focused on the influence of light absorption and lacked a systematic investigation of the overall water splitting process. Herein, hematite hollow-sphere-array photoanodes are fabricated through a facile hydrothermal method with polystyrene templates. Validating by simulations and experiments, the hollow sphere array is proved to enhance the efficiency of light harvesting, charge separation and surface reaction at the same time. With an additional annealing treatment in oxygen, a photocurrent density of 2.26 mA cm-2 at 1.23 V versus reversible hydrogen electrode can be obtained, which is 3.70 times larger than that with a planar structure in otherwise the same system. This work gains an insight into the photoelectrochemical water splitting process, which is valuable for the further design of advancing solar driven water splitting devices.

Iron-Based NASICON-Type Na4 Fe3 (PO4 )2 (P2 O7 ) Cathode for Zinc-Ion Battery: Zn2+ /Na+ Co-Intercalation Enabling High Capacity.

The development of high-performance cathode materials for aqueous zinc-ion batteries (ZIBs) based on nontoxic and earth-abundant elements remains a great challenge. This study introduces the iron-based NASICON-type material Na4 Fe3 (PO4 )2 (P2 O7) with carbon layer (NFPP@C) as a cathode material for ZIBs. When Zn2+ /Na+ dual ion electrolyte is employed, NFPP@C shows a high capacity of 114.4 mAh g-1 with two voltage plateaus, excellent rate capability (95 mAh g-1 at 2 A g-1 ), and long-term cycling stability (66.4 mAh g-1 after 1800 cycles at 1 A g-1 ). The outstanding electrochemical performance is ascribed to the synergistic use of NFPP@C and dual ion electrolyte. The NASICON-structure and carbon layer of NFPP@C enable fast ion and electron transport, whereas Na+ in the electrolyte reduces the concentration gradient between the electrode and electrolyte, and thus inhibits excessive extraction of Na+ from NFPP, maintaining structural stability. Moreover, Zn2+ /Na+ co-intercalation in NFPP@C brings two potential platforms and enhanced capacity.

Mechanical Stirring Synthesis of 1D Electrode Materials and Designing of Pyramid/Inverted Pyramid Interlocking for Highly Flexible and Foldable Li-Ion Batteries with High Mass Loading.

Flexible and foldable Li-ion batteries (LIBs) are presently attracting immense research interest for their potential use in wearable electronics but are still limited to electrodes with very small mass loading, low bending/folding endurance, and poor electrochemical stability during repeated bending and folding movements. Moreover, one-dimensional (1D) structured electrode materials have shown excellent electrochemical performance but are still restricted by the high cost and complicated fabrication process. Here, we present a very simple yet novel approach for fabricating extra-long Li4Ti5O12 (LTO) and LiCoO2 (LCO) nanofiber precursors by directly stirring the reagents in an atmospheric vessel. In addition, we present multilayer pyramid/inverted pyramid interlocking inside the LTO and LCO nanofiber films as well as between films and current collectors, which can create strengthened interfacial bonding like a zipper and tangentially disperse the strains generated during folding through the pyramidal planes and edges, leading to the realization of thick-film electrodes with outstanding electrochemical stability during folding movements. The foldable LIBs that are assembled with LTO and LCO nanofiber electrodes at a practical level of mass loading (14.9-19.4 mg cm-2) can maintain 102% of the initial capacity after 15 000 times of fully folding (180°) motions.

NEAT1 siRNA Packed with Chitosan Nanoparticles Regulates the Development of Colon Cancer Cells via lncRNA NEAT1/miR-377-3p Axis.

This study was for verifying that transfecting colon cancer cells (CCCs) with lncRNA NEAT1 packed with siRNA chitosan nanoparticles (CNPs) can suppress lncRNA NEAT1 and biological behaviors of the cells. siRNA targeting lncRNA NEAT1 expression vector was constructed and then transfected into CCCs after being packed with CNPs. Subsequently, the impact of the transfection on biological behaviors of the cells was evaluated. As a result, with high expression in CCCs, NEAT1 was negatively bound up with miR-377-3p in cases with colon cancer (CC), and dual luciferase reporter assay confirmed the potential binding region. Additionally, after downregulating NEAT1 in CCCs, transfection of NEAT1 siRNA packed with CNPs brought a great inhibition on cell proliferation and a promotion on apoptosis, and inhibiting miR-377-3p was able to offset the role of silencing NEAT1 in CCCs. Therefore, in our opinion, NEAT1 siRNA packed with CNPs can hinder the growth and metastasis of CCCs by knocking down NEAT1 in CC, and its mechanism may be achieved by targeting miR-377-3p, which offers a novel direction for treating CC.

SnO2 Nanosheets Anchored on a 3D, Bicontinuous Electron and Ion Transport Carbon Network for High-Performance Sodium-Ion Batteries.

Here, we demonstrate the in situ growth of SnO2 nanosheets on a freestanding carbonized eggshell membrane (CEM), which provides three-dimensional, bicontinuous electron and ion transport pathways through a massively interconnected carbon fiber skeleton and interpenetrated pore network, respectively. This CEM has other advantages such as the ability to alleviate mechanical stress during cycling as a buffer matrix. When used as an additive-free anode in a sodium-ion battery, SnO2 nanosheets can realize a complete electrochemical reaction and maintain good cycling stability with the help of a CEM. For instance, SnO2 nanosheets delivered a high reversible capacity of 656 mA h g-1 in the 5th cycle at 0.1 A g-1, approaching 98% of its theoretical specific capacity, and maintained a high reversible specific capacity of 420 mA h g-1 after 200 cycles at 0.2 A g-1.

Polymer-Promoted Synthesis of Porous TiO2 Nanofibers Decorated with N-Doped Carbon by Mechanical Stirring for High-Performance Li-Ion Storage.

Extensive efforts have been devoted to developing simple, low-cost, and high-production-yield methods to prepare hybrid materials with desired structural features for high-performance lithium storage. Here, a novel strategy is reported for fabricating the porous TiO2 nanofibers decorated with N-doped carbon (TiO2/C nanofibers) by a combination of mechanical stirring and the addition of a polymer in a beaker at ambient temperature, followed by calcination. The mechanical stirring process can provide homogeneous mixing of reactants in a solution, whereas the polymer acts not only as a structure-directing agent for fabricating one-dimensional nanofibers but also as the carbon and nitrogen source to generate N-doped carbon framework and porous structures. The TiO2/C nanofibers have average diameters of 500 nm and lengths up to 65 µm and are further composed of intercrossed TiO2 nanocrystals with sizes of 8 nm, with micropores centered at 1.5 nm and mesopores at 3-6 nm. The TiO2/C electrodes demonstrated a high reversible capacity (368 mAh g-1 at 0.25C after 200 cycles), good cycling performance (176 mAh g-1 at 10C over 2000 cycles), and excellent rate capability (97 mAh g-1 at 20C).

Recovery of phosphorus rich krill shell biowaste for uranium immobilization: A study of sorption behavior, surface reaction, and phase transformation.

Increased generation of shrimp shell from exploitation of krill results in emerging biowaste pollution, in addition, uranium pollution has drawn public concern due to the rapid development of nuclear power, uranium mining, and nuclear fuel processing. In this study, krill shells were recovered and used as a potential natural biosorbent for uranium immobilization, thereby enabling both uranium decontamination and krill shell reutilization. Interaction of uranium with krill shell surface and their transformation were investigated by using batch sorption experiments, scanning electron microscopy, and transmission electron microscopy. Krill shell had high uranium sorption ability. Uranium was transformed into a nano-scale precipitate. The mapping of phosphorus and uranium was related to the nano-scale precipitate, indicating that sorption of uranium was dependent on phosphorus. Surface chemisorption between phosphate in krill shell and uranium as well as the formation of the nano-scale precipitate were interpreted as the mechanism of uranium immobilization. Thus, natural krill shell waste has potential for extensive use as a promising and cost-effective sorbent for uranium immobilization and krill shell reutilization.

Synthesis of long hierarchical MoS2 nanofibers assembled from nanosheets with an expanded interlayer distance for achieving superb Na-ion storage performance.

MoS2 material is considered as a promising anode material candidate in Na-ion batteries (NIBs) due to its high theoretical capacity and layered structure. However, MoS2 nanosheets usually tend to restack or aggregate during the synthesis and cycling process, which makes the advantages of the separated nanosheets disappear. Here, we present a PVP-assisted synthesis for growing long hierarchical MoS2 nanofibers with a length up to 74.5 µm, which were further assembled from intercrossed curly nanosheets with expanded (002) interlayer spacings in the range of 0.62 nm to 1.14 nm. Such architectural design simultaneously combines multiple-scale structural features that are desired for Na-ion storage. On the one hand, the nanosheets can provide a large surface area which is in contact with the electrolyte, a short Na-ion diffusion pathway from the lateral side and facile Na-ion insertion and extraction through the expanded (002) interlayer; on the other hand, the hierarchical MoS2 nanofibers possess a one dimensional structure and a suitable amount of carbon, which can both serve as an electrical highway and prevent them from restacking, resulting in an enhanced electrochemical performance. When used as an anode in NIBs, they demonstrated excellent cycling performance (537 mA h g-1 at 0.1 A g-1 after 200 cycles, and 370 mA h g-1 at 2 A g-1 over 200 cycles) and outstanding rate capability (329 mA h g-1 at 10 A g-1).

Cost-Effective Alkaline Water Electrolysis Based on Nitrogen- and Phosphorus-Doped Self-Supportive Electrocatalysts.

Water splitting into hydrogen and oxygen in order to store light or electric energy requires efficient electrocatalysts for practical application. Cost-effectiveness, abundance, and efficiency are the major challenges of the electrocatalysts. Herein, this paper reports the use of low-cost 304-type stainless steel mesh as suitable electrocatalysts for splitting of water. The commercial and self-support stainless steel mesh is subjected to exfoliation and heteroatom doping processes. The modified stainless steel electrocatalyst displays higher oxygen evolution reaction property than the commercial IrO2 , and comparable hydrogen evolution reaction property with that of Pt. More importantly, an all-stainless-steel-based alkaline electrolyzer (denoted as NESSP//NESS) is designed for the first time, which possesses outstanding stability along with lower overall voltage than the conventional Pt//IrO2 electrolyzer at increasing current densities. The remarkable electrocatalytic properties of the stainless steel electrode can be attributed to the unique exfoliated-surface morphology, heteroatom doping, and synergistic effect from the uniform distribution of the interconnected elemental compositions. This work creates prospects to the utilization of low-cost, highly active, and ultradurable electrocatalysts for electrochemical energy conversion.

Growth of a Large-Area, Free-Standing, Highly Conductive and Fully Foldable Silver Film with Inverted Pyramids for Wearable Electronics Applications.

A promising new concept is the application of flexible and foldable conductive film or paper for wearable electronics, in which silver nanowires, carbon nanotubes, and graphene are primarily used as conductive materials. However, their insufficient nanostructure contacts lead to poor electrical conductivity and mechanical fracture. Here, we demonstrate a simple and innovative strategy for fabricating a free-standing silver film with inverted pyramids by replicating pyramids on a textured silicon wafer under a hydrothermal reaction. In this unique structure, the inverted pyramids on the film surface can provide sufficient buffer space for a mechanically foldable and unfoldable cushion, and the continuous film ensures an uninterrupted electron transport pathway. As a result, the silver film with inverted pyramids can exhibit extremely high conductivity, with a sheet resistance as low as 2.55 × 10-3 Ω/sq, corresponding to an electrical conductivity of 4.2 × 105 S cm-1 for a 9.2-µm-thick film (67.7% of bulk silver's conductivity). Surprisingly, this film has outstanding mechanical folding stability, with less than a 0.5% deviation from the initial resistance after 35,000 repetitive folding and unfolding cycles when tested at the folding site. The film is free-standing, thin, flexible, foldable, and suitable for cutting and patterned growth, which makes it suitable for wearable electronics, showing a much wider range of applications than substrate-based ones.