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The Li dendrite growth and the liquid electrolyte volatilization under semi-open architecture are intrinsic issues for Li-O2 battery. In this work, we propose a non-Newtonian fluid quasi-solid electrolyte (NNFQSE) SiO2-SO3Li/PVDF-HFP, which has both shear-thinning and shear-thickening properties. The component interactions among the sulfonated silica nanoparticles, liquid electrolyte, and polymer network are beneficial for decent Li+ conductivity and high liquid electrolyte retention without volatilization. Furthermore, NNFQSE exhibits shear-thinning property to eliminate the stress of dendrite growth during repeated cycling. Meanwhile, when the force suddenly increases, such as a high current rate, the NNFQSE may dynamically turn shear-thickening to respond and mechanically stiffen to inhibit the lithium dendrite penetration. By coupling with the NNFQSE, the lithium symmetrical battery can run over 2000 h under 1 mA cm−2 at room temperature, and the quasi-solid Li-O2 battery actualizes long life above 5000 h at 100 mA g−1. Lithium dendrite growth and liquid electrolyte volatilization limit the further development of lithium-oxygen batteries. Here, authors report a non-Newtonian fluid quasi-solid electrolyte to address those issues, which improve the life duration of the lithium-oxygen batteries. [ABSTRACT FROM AUTHOR]

Lithium-sulfur batteries (LSBs) are regarded as the most promising next-generation energy system due to their high theoretical energy density. However, LSBs suffer the "shuttle effect" if undergoing the solid-liquid-solid sulfur conversion process during cycling. Herein, we design a solvent-in-salt (SIS) electrolyte with co-solvent vinylene carbonate (VC) to synthesize an in situ dense cathode electrolyte interface (CEI) and successfully change sulfur conversion into a solid-solid way to avoid shuttle effect by separating the contact of sulfur and ether solvent. Dense CEI is formed at the beginning of first discharge by the combined action of SIS electrolyte and filmogen VC. Experiments and simulations show that SIS electrolyte controls the initial formed lithium polysulfides (LiPSs) to stay very closely on the cathode surface, and then converts them into a dense CEI film. As a result, Coulombic efficiency (above 99%) and cycling performance of LSBs are improved. Furthermore, the in situ dense CEI can nearly stop the self-discharge of LSBs, and enable the LSBs to work under a pretty lean electrolyte condition. [ABSTRACT FROM AUTHOR]

To obtain highly efficient and robust electrocatalysts for formic acid oxidation, PdxCuy/C binary catalysts with porous structures were successfully prepared via electrochemical dealloying. Catalysts with different Pd/Cu atomic ratios were characterized through transmission electron microscopy, inductively coupled plasma atomic emission spectroscopy, and X-ray diffraction. The optimized dealloyed Pd1Cu4/C catalyst with a porous structure displayed a catalytic activity of 2611 A g−1 and high stability (30.5% activity retention under repeated cyclic voltammetric (CV) patrol), whereas a commercial Pd/C-Aldrich benchmark showed a catalytic activity of 785 A g−1 and retained 16.5% activity. A detailed mechanistic study of electrochemical dealloying was performed. Under repeated CV patrol, Pd-enriched porous architectures evolved from Pd-poor surfaces, accompanied by successive Cu dissolution. [ABSTRACT FROM AUTHOR]

In this study, La(OH)3-modified magnetic sodium carboxymethyl cellulose (La-MC) was prepared as adsorbents for phosphate, which exhibited excellent adsorption performance up to 62.98 mg P/g and magnetic property for easy recovery. The recovered adsorbents after phosphate sorption were subsequently used for photocatalytic reduction of Cr(VI) and possessed good photocatalytic activity. This work provided an excellent reference for developing a new way of extending life cycle of adsorbents by combining phosphate adsorption with photocatalysis for sequential removal of pollutants from water in the future. [ABSTRACT FROM AUTHOR]

A high-performance Ni/Mo co-doped lithium manganate composite material, LiNi0.03Mo0.01Mn1.96O4, is prepared by a solid-state method, then a biomass-derived carbon layer with ethyl cellulose as the carbon source is applied to the surface of the composite particles. We find that carbon layer with the proper loading can significantly enhance the material's cyclic stability and capacity at high discharge rates. At rates of 5C and 10C, our optimal sample (LNMMO-3wt%C), with 3 wt% carbon layer loading, has discharge capacities up to 114 and 98 mAh g−1, respectively, which are 10 and 8% higher than those of the uncoated co-doped material. Further, the carbon layer coating significantly improves the material's stability at high discharge rates: the capacity retention of LNMMO-3wt%C after 400 cycles at discharge rates of 5C and 10C is high reaching 93.6 and 88.1%, respectively, compared with 91.4 and 74.3% for uncoated LNMMO. Based on our experimental results and analysis, we attribute the enhanced stability and capacity at high discharge rates to two factors: (i) enhanced conductivity and (ii) reduced Mn3+ dissolution, combined with significantly decreased resistance from Li+ ion intercalation/de-intercalation, due to the uniformity of the carbon layer coating.Ni/Mo-doped lithium manganate, LiNi0.03Mo0.01Mn1.96O4, is coated with carbon layer by using biomass-based feedstock ethyl cellulose (EC) as carbon source. The carbon layer coating results significantly improved stability at high discharging rates: the capacity retention of our optimal sample (LNMMO-3wt%C) material after 400 cycles at discharging rates of 5C and 10C are high up to 93.6 and 88.1%, respectively, compared with 91.4 and 74.3% for uncoated material. [ABSTRACT FROM AUTHOR]

Abstract: Through decorating commercial Pt/C catalyst with a binary oxide of silicon and tin, a catalyst with significantly enhanced self-humidification capacity and ultra-high stability has been successfully prepared. After 5000 cycles, ECSA and ORR activity decay by only 30% and 28.4%, respectively, for our optimal decorated catalyst, compared with 75% and 99.9% for undecorated Pt/C under the same conditions. We attribute this improvement to the prevention of Pt nanoparticle aggregation and the synergistic effects between the Pt active component and the binary oxide. The decorated catalyst also exhibits excellent self-humidification. Under non-humidified operating conditions, a membrane electrode assembly (MEA) with a decorated Pt/C catalyst anode is discharged at 0.6 V for 8 h with only slight current density decay, whereas serious decay is observed for an MEA with a non-decorated Pt/C anode. The catalysts are characterized using XRD, SEM/TEM, XPS, and contacted angle measurement. We find that the dissolution, migration, and aggregation of Pt nanoparticles can be effectively prevented by decoration with the binary oxide, and that the contact angle is decreased by 56°, indicating great improvement in the catalyst’s wettability. The interactions between Pt and oxide, Sn and Si are revealed by XPS analysis. This work may provide a facile and effective way to address the durability and humidification issues of PEM fuel cells.Graphical Abstract: An oxide modified Pt/C catalyst was prepared by decorating the commercial Tanaka Pt/C catalyst with a binary oxide of Sn and Si, the catalyst exhibited significantly enhanced stability/durability, slightly enhanced activity and excellent self-humidification property. The catalysts were characterized with HRTEM, XPS etc. The enhancements should be attributed to the prevention of the coated binary oxide to the aggregation of Pt, the corrosion of carbon support. And self-humidification may be resulted from the wettability of the silicon oxide. [ABSTRACT FROM AUTHOR]

In this work, we report the synthesis of ordered mesoporous carbon sheets (OMCS) with graphene-like morphology and their applications as the support for electrocatalysts. This lamellar material exhibits uniform mesoporous channels and ease of modification by using different nitrogen sources, such as melamine, urea, and ammonia. Nitrogen-doping on this material leads to a high specific surface area of 761 m2 g−1 and uniform pores with a diameter of 9 nm. Electrochemical tests show that the N-doped OMCS possesses high catalytic activities on the oxygen reduction reaction, which can be attributed to the pyridinic-type and pyrrolic-type nitrogen activating nearby carbon atoms. In addition, we demonstrate that the unique physical structure and surface chemical properties of OMCS improve the dispersion and structure of supported metal Ru nanoparticles, which lead to enhance oxygen evolution reaction activity. [ABSTRACT FROM AUTHOR]

Nano-sized cobalt particles with the diameter of 2 nm were prepared via an organic colloidal process with sodium formate, ethylene glycol and sodium citrate as the reducing agent, the solvent and the complexing agent, respectively. The effects of sodium citrate on the yield, crystal structure, particle size and size distribution of the prepared nano-sized cobalt particles were then investigated. The results show that the average particle diameter decreases from 200 nm to 2 nm when the molar ratio of sodium citrate to cobalt chloride changes from 0 to 6. Furthermore, sodium citrate plays a crucial role in the controlling of size distribution of the nano-sized particles. The size distribution of the particle without sodium citrate addition is in range from tens of nanometers to 300 or 400 nm, while that with sodium citrate addition is limited in the range of (2±0.25) nm. Moreover, it is found that the addition of sodium citrate as a complex agent could decrease the yield of the nano-sized cobalt particle. [ABSTRACT FROM AUTHOR]

On the basis of stochastic resonance (SR) theory a study of the detection of photoacoustic (PA) signals without a lock-in amplifier is presented. The applicability of the SR method is investigated both with simulated signals calculated by use of a Gaussian model and with experimental PA signals. Signal-to-noise ratio (SNR) is improved substantially by adjusting the properties of a non-linear system to realize SR. By use of this method the lock-in amplifier can be removed from a PA spectrometer. [ABSTRACT FROM AUTHOR]

It is eager to develop high-performance and cheap bifunctional electrochemical catalysts for both of the oxygen reduction reaction (ORR) or oxygen evolution reaction (OER) for the energy crisis and environmental problems. Herein, we report a series of ZIF-derived Co-P-C co-doped polyhedral materials with a well-defined morphology. The optimized catalyst Co/P/MOFs-CNTs-700 exhibited favorable electrochemical activities with the lowest overpotential of 420 mV to achieve the current density of 10 mA cm−2 for OER and the half potential of 0.8 V for ORR in 0.1 M NaOH. The performance can be well improved by doping phosphorous resource which greatly changed its morphology. Meanwhile, the doped carbon resources also improve the conductivity, which makes it a promising bifunctional electrochemical catalyst and can be comparable with the commercial electrocatalysts. [ABSTRACT FROM AUTHOR]

Core-shell structured catalysts, made by placing either a monolayer or a thin layer of a noble metal on relatively cheap core-metal nanoparticles, are fascinating and promising fuel cell catalysts due to their high utilization of noble metals. Here, we report our development of a core-shell structured catalyst, Ru@Pt/C, generated by a novel and facile pulse electrochemical deposition (PED) approach. We demonstrate that compared with a commercial Pt/C catalyst, this novel catalyst achieves over four times higher mass activity towards the anodic oxidation of methanol, and 3.6 times higher mass activity towards the cathodic reduction of oxygen. Importantly, we find that the intrinsic activity of Pt in this Ru@Pt/C catalyst is doubled due to the formation of the core-shell structure. The catalyst also shows superior stability: even after 2000 scans, it still retains up to 90% of the peak current. Our findings demonstrate that this novel PED approach is a promising method for preparing high-performance core-shell catalysts for fuel cell applications. [ABSTRACT FROM AUTHOR]