Stress-Dispersed Superstructure of Sn3 (PO4 )2 @PC Derived from Programmable Assembly of Metal-Organic Framework as Long-Life Potassium/Sodium-Ion Batteries Anodes.

The structures of anode materials significantly affect their properties in rechargeable batteries. Material nanosizing and electrode integrity are both beneficial for performance enhancement of batteries, but it is challenging to guarantee optimized nanosizing particles and high structural integrity simultaneously. Herein, a programmable assembly strategy of metal-organic frameworks (MOFs) is used to construct a Sn-based MOF superstructure precursor. After calcination under inert atmosphere, the as-fabricated Sn3 (PO4 )2 @phosphorus doped carbon (Sn3 (PO4 )2 @PC-48) well inherited the morphology of Sn-MOF superstructure precursor. The resultant new material exhibits appreciable reversible capacity and low capacity degradation for K+ storage (144.0 mAh g-1 at 5 A g-1 with 90.1% capacity retained after 10000 cycles) and Na+ storage (202.5 mAh g-1 at 5 A g-1 with 96.0% capacity retained after 8000 cycles). Detailed characterizations, density functional theory calculations, and finite element analysis simulations reveal that the optimized electronic structure and the stress-dispersed superstructure morphology of Sn3 (PO4 )2 @PC promote the electronic conductivity, enhance K+ / Na+ binding ability and improve the structure stabilization efficiently. This strategy to optimize the structure of anode materials by controlling the MOF growth process offer new dimension to regulate the materials precisely in the energy field.

Design of Boron Carbonitrides-Polyaniline (BCN-PANI) assembled supercapacitor with high voltage window.

Boron carbonitrides (BCN) have been widely concerned in the field of energy storage and conversion. However, the energy storage mechanism of electrical double-layer behavior and their stacked-layer structure severely limit the improvement of capacitance, thereby hindering their further development in energy storage. Therefore, an ultrasonic-ball milling method was first chosen to obtain BCN nanosheets, together with a feasible way of polyaniline (PANI) modification performed to boost the capacitive reaction of BCN nanosheets. For the first time, a BCN-PANI-based symmetric supercapacitor device can reach a high voltage window of 3.0 V when 1 M Et4N·BF4 was chosen as the electrolyte. The working voltage of 3.0 V is three times that of a device with pure PANI with the ultrahigh energy density of 67.1 W h kg-1, superior to most of the reported PANI-based devices. The eminent electrochemical performance provides a promising strategy to pave the way for configuring carbon-based multiple composite electrodes for other energy storage devices.

Facile Fabrication of a Foamed Ag3CuS2 Film as an Efficient Self-Supporting Electrocatalyst for Ammonia Electrolysis Producing Hydrogen.

Ammonia (NH3) is one of the hydrogen carriers that has received extensive attention due to its high hydrogen content and carbon-free nature. The ammonia electro-oxidation reaction (AOR) and the liquid AOR (LAOR) are integral parts of an ammonia-based energy system. The exploration of low-cost and efficient electrocatalysts for the AOR and LAOR is very important but very difficult. In this work, a novel self-supporting AOR and LAOR bifunctional electrocatalyst of a Ag3CuS2 film is synthesized by a simple hydrothermal method. The Ag3CuS2 film without a substrate shows efficient catalytic activity and enhanced stability for NH3 electrolysis in both aqueous ammonia solution and liquid ammonia, including an onset potential of 0.7 V for the AOR and an onset potential of 0.4 V for the LAOR. The density functional theory calculations prove that compared to Cu atoms, Ag atoms with appropriate charge density on the surface of Ag3CuS2 are more electrocatalytically active for NH3 splitting, including the low energy barrier in the rate-determining *NH3 dehydrogenation step and the spontaneous tendency in the N2 desorption process. Overall, the foamed Ag3CuS2 film is one of prospective low-cost and stable electrocatalysts for the AOR and LAOR, and the self-supporting strategy without a substrate provides more perspectives to tailor more meaningful and powerful electrocatalysts.

In situ configuration of dual S-scheme BP/(Ti3C2Tx@TiO2) heterojunction for broadband spectrum solar-driven photocatalytic H2 evolution in pure water.

Artificial photocatalysis with high-efficiency is a promising route for storing sustainable energy from water splitting. Whereas it is challenging to broaden the solar-spectrum responsive window for harvesting high level of conversion. Herein, based on the band-matching engineering theory, a design of dual S-Scheme heterojunction system is proposed and established in a BP/(Ti3C2Tx@TiO2) composite photocatalyst. The complementary light response region between TiO2 and BP realizes the extension of solar energy utilization over a broad absorption window. Furthermore, this specific band-matching configuration endows spatially long-lived charge carriers with greater accumulation on the divided sub-systems, thereby maintaining the sufficient potential energy capacity associated with excellent photocatalytic properties (H2 evolution rate of 564.8 µmol h-1 g-1 and AQE of 2.7% at 380 nm in pure water). This work describes a promising protocol of designing advanced broadband light-activated photocatalytic systems for solar-chemical energy conversion applications.

Electrochemical Surface Restructuring of Phosphorus-Doped Carbon@MoP Electrocatalysts for Hydrogen Evolution.

The hydrogen evolution reaction (HER) through electrocatalysis is promising for the production of clean hydrogen fuel. However, designing the structure of catalysts, controlling their electronic properties, and manipulating their catalytic sites are a significant challenge in this field. Here, we propose an electrochemical surface restructuring strategy to design synergistically interactive phosphorus-doped carbon@MoP electrocatalysts for the HER. A simple electrochemical cycling method is developed to tune the thickness of the carbon layers that cover on MoP core, which significantly influences HER performance. Experimental investigations and theoretical calculations indicate that the inactive surface carbon layers can be removed through electrochemical cycling, leading to a close bond between the MoP and a few layers of coated graphene. The electrons donated by the MoP core enhance the adhesion and electronegativity of the carbon layers; the negatively charged carbon layers act as an active surface. The electrochemically induced optimization of the surface/interface electronic structures in the electrocatalysts significantly promotes the HER. Using this strategy endows the catalyst with excellent activity in terms of the HER in both acidic and alkaline environments (current density of 10 mA cm-2 at low overpotentials, of 68 mV in 0.5 M H2SO4 and 67 mV in 1.0 M KOH).

Na2 FePO4 F/Biocarbon Nanocomposite Hollow Microspheres Derived from Biological Cell Template as High-Performance Cathode Material for Sodium-Ion Batteries.

We have successfully synthesized Na2 FePO4 F/biocarbon nanocomposite hollow microspheres from FeIII precursor as cathodes for sodium-ion batteries through self-assembly of yeast cell biotemplate and sol-gel technology. The carbon coating on the nanoparticle surface with a mesoporous structure enhances electron diffusion into Na2 FePO4 F crystal particles. The improved electrochemical performance of Na2 FePO4 F/biocarbon nanocomposites is attributed to the larger electrode-electrolyte contact area and more active sites for Na+ on the surface of hollow microspheres compared with those of Na2 FePO4 F/C. The Na2 FePO4 F/biocarbon nanocomposite exhibits a high initial discharge capacity of 114.3 mAh g-1 at 0.1 C, long-cycle stability with a capacity retention of 74.3 % after 500 cycles at 5 C, and excellent rate capability (70.2 mAh g-1 at 5 C) compared with Na2 FePO4 F/C. This novel nanocomposite hollow microsphere structure is suitable for improving the property of other cathode materials for high-power batteries.

Boron carbonitride with tunable B/N Lewis acid/base sites for enhanced electrocatalytic overall water splitting.

In-depth research on energy storage and conversion is urgently needed; thus, water splitting has become a possible method to achieve sustainable energy utilization. However, traditional carbon material with high graphitization degree exhibits a relatively low electrocatalytic oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) activity as it is electrochemically inert. In this work, according to the Lewis theory of acids and bases and the density functional theory (DFT) results, which show that the enriched heteroatom of B/N in the boron carbonitride (BCN) system may introduce stronger adsorption strength of OH*/H2O, respectively, we have designed and synthesized self-supporting BCN materials with different enrichment degrees of B/N (B-BCN/N-BCN) using carbon paper as substrate. Furthermore, by adjusting the contents of B and N, the optimum electrocatalytic performance of overall water splitting was obtained in which the onset voltage of water splitting on B-BCN//N-BCN was lower than 1.60 V. Our strategy of synthesizing materials with different heteroatom enrichment to improve the electronic environment of materials has opened up new opportunities for developing efficient metal-free electrocatalysts.

A Freestanding 3D Heterostructure Film Stitched by MOF-Derived Carbon Nanotube Microsphere Superstructure and Reduced Graphene Oxide Sheets: A Superior Multifunctional Electrode for Overall Water Splitting and Zn-Air Batteries.

Developing a scalable approach to construct efficient and multifunctional electrodes for the hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and oxygen reduction reaction (ORR) is an urgent need for overall water splitting and zinc-air batteries. In this work, a freestanding 3D heterostructure film is synthesized from a Ni-centered metal-organic framework (MOF)/graphene oxide. During the pyrolysis process, 1D carbon nanotubes formed from the MOF link with the 2D reduced graphene oxide sheets to stitch the 3D freestanding film. The results of the experiments and theoretical calculations show that the synergistic effect of the N-doped carbon shell and Ni nanoparticles leads to an optimized film with excellent electrocatalytic activity. Low overpotentials of 95 and 260 mV are merely needed for HER and OER, respectively, to reach a current density of 10 mA cm-2 . In addition, a high half-wave potential of 0.875 V is obtained for the ORR, which is comparable to that of Pt/RuO2 and ranks among the top of non-noble-metal catalysts. The use of an "all-in-one" film as the electrode leads to excellent performance of the homemade water electrolyzer and zinc-air battery, indicating the potential of the film for practical applications.

Na3V2(PO4)3/Porous Carbon Skeleton Embellished with ZIF-67 for Sodium-Ion Storage.

Sodium super ionic conductor (NASICON) Na3V2(PO4)3 (NVP) is a type of promising cathode material for sodium-ion batteries (SIBs) with superior structural integrity, high energy density, and fast diffusion of sodium ions. However, NVP suffers from intrinsically low electrical conductivity, which results in poor rate performance. Herein, we report on the outstanding cathode performance of Na3V2(PO4)3 (NVP@C-ZIF67) wrapped by the ZIF-67-derived carbon, which was prepared by sol-gel method and solid-phase method. Electrochemical measurements show an initial discharge-specific capacity of 135 mA h g-1 at 1 C, and the discharge capacity maintains 82 mA h g-1 after 1000 cycles at 10 C. The results indicate the improvement in electrical conductivity and electrochemical performance due to the Co doping from ZIF-67. Moreover, we calculate the diffusion coefficient of sodium ions by the cyclic voltammetry (CV, DNa+ = 1.521 × 10-11 and 2.3484 × 10-11 cm2 s-1 for charging and discharging, respectively) and the galvanostatic intermittent titration technique (GITT, DNa+ ranges from 10-11-10-15 cm2 s-1). The exceptional performance is ascribed to the excellent structural stability and outstanding electrical conductivity of NVP modified by porous carbon skeleton and ZIF-67-derived carbon.

Graphene-Amplified Photoelectric Response of CdS Nanoparticles for Cu2+ Sensor.

Graphene/CdS composites were synthesized through the direct deposition of CdS nanoparticles on graphene sheets. The high conductivity of graphene sheets and the intimate heterointerfacial connection between graphene sheets and CdS nanoparticles provided prominent advantages for enhancing light absorption and facilitating the transfer of photogenerated carriers from CdS nanoparticles, thus leading to an effectively separation of electron-hole pairs and consequently an improvement in photocurrent intensity. A highly sensitive and selective photoelectrochemical sensor for detecting copper ions (Cu2+) was developed based on the interaction between Cu2+ and CdS by forming CuxS-coated CdS nanoparticles, which serves as the recombination centers, impedes the transfer of electron from the conduction band of CdS to graphene sheets, and consequently leads to a decrease in photocurrent intensity. The sheets not only effectively transferred the photogenerated electrons deriving from CdS nanoparticles but also resulted in an enhancement in photocurrent intensity in the presence of various metal ions except Cu2+. The sheets amplified the photoelectric response of CdS semiconductor for Cu2+ sensing, in which the photocurrent intensity decreased dramatically.

Mulberry-like heterostructure (Fe-O-Ti): a novel sensing material for ethanol gas sensors.

The gas sensors have been widely used in various fields, to protect the safety of life and property. A novel heterostructure of Fe-O-Ti nanoparticles is fabricated by hydrothermal and wet chemical deposition methods. The Fe-O-Ti nanoparticles with a large number of pores possess high surface area, which is in favour of high-performance gas sensors. Compared with pure Fe2O3 and TiO2, the Fe-O-Ti composite exhibits obviously enhanced sensing characteristics, such as faster response-recovery time (T res = 6 s, T rec = 48 s), higher sensing response (response = 35.6) and better selectivity. The results show that the special morphology and large specific surface area of mulberry-like Fe-O-Ti heterostructures provided a large contact area for gas reactions.

Deficits of synaptic functions in hippocampal slices prepared from aged mice null α7 nicotinic acetylcholine receptors.

Alpha 7 (α7) nicotinic acetylcholine receptor (α7-nAChR) is one of most high expressed nAChR subtypes in the brain. The activation of nAChRs enhances animal cognitive, learning and memory abilities. However, the role of genetic knockout (KO) of α7-nAChRs in animal cognition-associated behaviors is still obscure. An early report showed that α7-nAChR KO mice did not exhibit behavioral phenotypes, concerning the roles of α7-nAChRs in normal, cognition-associated behaviors. Later, α7-nAChR KO mice were found a deficit in animal spatial discrimination. The roles of α7-nAChRs in the alterations of hippocampal synaptic function during aging process are largely unknown. Here, we address this question by examining synaptic function using field potential recording in hippocampal slice preparations from adult (12-14 months old) and aged (22-24 months old) α7-nAChR KO and age-matched wild-type (WT) mice. We found that compared to aged WT mice, aged α7-nAChR KO mice exhibited significantly reduced size of evoked field synaptic potential and impaired long-term potentiation (LTP) in hippocampal CA3-CA1 synapses. However, adult α7-nAChR KO mice did not show a clear deficit in LTP although the basic synaptic transmission was also reduced compared to adult WT mice. In both age groups, there was no significant difference of paired-pulse facilitation between α7-nAChR KO and WT mice. Collectively, this study provides direct evidence, for the first time, that the impaired synaptic function occurs in aged α7-nAChR KO mice, suggesting an importance of α7-nAChRs in maintaining cognitive function during aging process.

Synthesis of CdSe quantum dots using various long-chain fatty acids and their phase transfer.

Monodispersed colloidal photoluminescent CdSe quantum dots (QDs) were synthesized via an organic approach by using cadmium oxide and elemental selenium as precursors, and long-chain fatty acids as surface ligands. The hydrocarbon chain length of the fatty acid was adjusted to investigate the effect on CdSe QDs. The fatty acid ligands with different hydrocarbon chain lengths showed an apparent effect on the nanocrystal nucleation and growth which is the key controlling the size, size distribution and crystal structure of resulting CdSe QDs. This effect was attributable to the steric hindrance of different hydrocarbon length of the fatty acids, which affected the reactivity of the monomers and nanocrystals during the nanocrystal nucleation and growth. The water-soluble CdSe QDs were obtained by encapsulating the CdSe ODs in oil phase with amphiphilic poly(styrene-co-maleic anhydride) (PSMA)-ethanolamine (EA) polymers, which made it possible for further applications of the CdSe QDs in aqueous environment such as surface functionalization for biological labeling and application in photocatalysis and photosensitization.