Latest ArticlesSodium-ion batteries (SIBs) are promising alternatives to lithium-ion batteries (LIBs) for large-scale energy storage considering the abundance and low cost of Na-containing resources. However, the energy density of SIBs has been limited by the typically low specific capacities of traditional intercalation-based cathodes. Metal fluorides, in contrast, can deliver much higher capacities based on multi-electron conversion reactions. Among metal fluorides, CuF2 presents a theoretical specific capacity as high as 528 mAh/g while its Na-ion storage mechanism has been rarely reported. Here, we report CuF2 as a SIB cathode, which delivers a high capacity of 502 mAh/g but suffers from poor electrochemical reversibility. As a solution, we adjust the cell configuration by inserting a carbon-coated separator, which hinders the transportation of dissolved Cu ions and improves the reversibility of the CuF2 cathode. By using in-situ XRD measurements and theoretical calculation, we propose that a one-step conversion reaction occurs during the discharge process, and a reconversion reaction competes with the oxidization of Cu to dissolved Cu ion during the charge process.
In recent years, especially when there is increasing concern about the safety issue of lithium-ion batteries (LIBs), aqueous Zn-ion batteries (ZIBs) have been getting a lot of attention because of their cost-effectiveness, materials abundance, high safety, and ecological friendliness. Their working voltage and specific capacity are mainly determined by their cathode materials. Vanadium oxides are promising cathode materials for aqueous ZIBs owing to their low cost, abundant resources, and multivalence. However, vanadium oxide cathodes still suffer from unsatisfactory capacity, poor stability, and low electrical conductivity. In this work, cascading V2O3/nitrogen doped carbon (V2O3/NC) hybrid nanosheets are prepared for high-performance aqueous ZIBs by pyrolyzing pentyl viologen dibromide (PV) intercalated V2O5 nanosheets. The unique structure features of V2O3/NC nanosheets, including thin sheet-like morphology, small crystalline V2O3 nanoparticles, and conductive NC layers, endow V2O3/NC with superior performance compared to most of the reported vanadium oxide cathode materials for aqueous ZIBs. The V2O3/NC cathode exhibits the discharge capacity of 405 mAh/g at 0.5 A/g, excellent rate capability (159 mAh/g at 20 A/g), and outstanding cycling stability with 90% capacity retention over 4000 cycles at 20 A/g.
The effects of two solid-based hydrogen peroxides sodium percarbonate (SPC) and calcium peroxide (CP) on waste activated sludge (WAS) disintegration were investigated. Both oxidants achieved efficient WAS disintegration for the synergistic effect of alkaline and oxidation. The strong alkaline condition led to the leakage of ammonia and the existence of abundant calcium ions accelerated the fixation of phosphorus via precipitation in CP WAS disintegration process. However, the spongy-like layer and low pH condition retarded the release of gaseous ammonia in SPC group. Hydroxyl radical was the main oxygen reactive species in SPC approaches which were more intense than CP by electron spin resonance (ESR) analysis. CP treated WAS contented more small particle size matter and total suspended solids (TSS) increased dramatically. In conclusion, CP pretreated sludge was more suitable for fertilization, while SPC was in favor of anaerobic digestion. This study clarified the differences between these two oxidants and their intermediates on nutrients release in sludge disintegration.
2D transition metal dichalcogenides (TMDCs) have drawn an enormous amount of attention due to their fascinating properties and application potential in next-generation information process and storage. However, the lack of proper synthesis approach limits their application. Here, we report a controllable synthesis method to grow ultrathin MS2 (M = Ti, Nb, Zr) nanosheets with H2S-assisted chemical vapor deposition (CVD). We found that the presence of H2S plays an important role to control the morphology of nanosheets including the lateral size and the nucleation density. With the assistance of H2S, the growth of MS2 shows much thinner thickness with largely decreased nucleation density, beneficial for the device application, which can be attributed to the kinetics dominated growth. Our method hence opens a new avenue for the CVD growth of 2D TMDCs and the corresponding heterojunction, and paves the way for exploring their intriguing properties and applications.
Morphology-controlled electrocatalysts with the ability of CO2 adsorption/activation, mass transfer, high stability and porosity are much desired in electrochemical CO2 reduction reaction (CO2RR). Here, three kinds of multi-dimensional nanostructures (i.e., hollow sphere, nanosheets and nanofibers) have been successfully produced through the modulation of porphyrin-based covalent organic frameworks (COFs) with various modulators. The obtained nanostructures with high-stability, large surface-area, and single metal sites enable efficient CO2RR into CH4. Notably, they all exhibit higher FE (hollow sphere, 68.2%; nanosheet, 64.2% and nanofiber, 71.0%, −0.9 V) than COF-366-Cu (43.0%, −0.9 V) after morphology control. Noteworthy, the FE of COF-366-Cu (HS) keeps higher than 52.4% over a wide potential range from −0.9 V to −1.1 V and the achieved FECH4+C2H4 (82.8%, −0.9 V) is superior to most of reported COFs and copper-based electrocatalysts. This work paves a new way in the exploration of COF-based multi-dimensional nanostructures applicable in efficient CO2RR to CH4.
Chemodynamic therapy (CDT) has attracted tremendous interest in cancer therapy because it is independent of oxygen and photoirradiation. However, the therapeutic efficacy of CDT is restricted by insufficient H2O2 levels in tumor cells. Herein, employing endogenous GSH as a template and cationic polymeric chitosan (CS) as crosslinker and stabilizer exhibiting easy cell uptake, red luminescent gold nanoclusters (denoted CS-GSH@AuNCs) were successfully synthesized in HeLa cells. The in situ synthesized CS-GSH@AuNCs exhibited both superoxidase dismutase (SOD) and peroxidase (POD)-like activity, which could promote the production of H2O2 from superoxide anion radicals (O2·−) and then ·OH. The combination of GSH elimination and H2O2 elevation boosted the generation of ·OH, which could trigger cancer cell apoptosis and death. The enzyme-like activity of CS-GSH@AuNCs could be effectively activated under acidic conditions, and showed a high killing effect on tumor cells but minimal toxicity to normal cells. The developed GSH consumption and ·OH promotion theranostic platform is an innovative route for enhanced CDT by the amplification of oxidative stress.
Due to the technology limitation and inferior deNOx efficiency of urea selective catalytic reduction (SCR) catalysts at low temperatures, passive NOx adsorber (PNA) for decrease of NOx, CO and hydrocarbons (HCs) during "cold start" of vehicles was proposed to meet the further tighten NOx emission regulations in future. Among them, Pd modified zeolite PNA materials have received more attention because of their excellent NOx storage capacity, anti-poisoning and hydrothermal stability and since Pd/zeolite PNA was proposed, a variety of advanced characterization methods have been applied to investigate its adsorption behavior and structure-performance relationship. The comprehension of the active sites and adsorption chemistry of Pd/zeolite PNA was also significantly improved. However, there are few reviews that systematically summarize the recent progress and application challenges in atomic-level understanding of this material. In this review, we summarized the latest research progress of Pd/zeolite PNA, including active adsorption sites, adsorption mechanism, material physicochemical properties, preparation methods, storage and release performance and structure-performance relationships. In addition, the deactivation challenges faced by Pd/zeolite PNA in practical applications, such as chemical poisoning, high temperature hydrothermal aging deactivation, etc., were also discussed at the micro-level, and some possible effective countermeasures are given. Besides, some possible improvements and research hotspots were put forward, which could be helpful for designing and constructing more efficient PNA materials for meeting the ultra-low NOx emission regulation in the future.
A facile solvo-thermal approach was successfully employed to prepare titanium oxide (TiO2) nano-aggregates with simultaneous copper particles anchoring. The as-synthesized composite could convert CO2 into CH4 and CO products under simulated solar irradiation. The impact of copper loading amounts on the photo-reduction capability was evaluated. It was found proper amount of Cu loading could enhance the activity of CO2 photo-reduction. As a result, the optimal composite (TiO2-Cu-5%) consisting of TiO2 supported with 5% (mole ratio) Cu exhibits 2.2 times higher CH4 yield and 3 times higher CO yield compared with pure TiO2. Conduction band calculated from the band gap and valence X-ray photoelectron spectroscopy (XPS) indicated TiO2 nano-aggregates have suitable band edge alignment with respect to the CO2/CH4 and CO2/CO redox potential. Furthermore, with involving of Cu particles, an efficient separation of photo-generated charges was achieved on the basis of photocurrent response and photoluminescence spectra results, which contributed to the improved photo-catalytic performance. The present work suggested that the Cu-decorated TiO2 could serve as an efficient photo-catalyst for solar-driven CO2 photo-reduction.
Two pairs of Pt(II) enantiomers ((RR)/(SS)-PyPt, ((RR)/(SS)-Py: N, N'-(1, 2-diphenylethane-1, 2-diyl)dipicolinamide; (RR)-P/M-QPt, ((RR)/(SS)-Q: N, N'-((1R, 2R)-1, 2-diphenylethane-1, 2-diyl)bis(quinoline-2-carboxamide)) were synthesized, respectively, with good circularly polarized luminescence (CPL) and tunable dissymmetry factors (g) by molecular self-induction with (RR)/(SS)-1, 2-diphenylethane-1, 2-diamine as carbon chiral sources. In the (RR)-P-QPt and (SS)-M-QPt, specific P- and M-configurations were effectively induced from intrinsic chiral carbon centres (R or S), ingeniously avoiding the racemic mixture formation and chiral separation. Furthermore, the chirality originating from both chiral carbon centres and helicene-like structure improves the g factor significantly, which provides a new molecular design strategy for chiral Pt(II) enantiomers with good CPL properties.
Localized surface plasmon resonance (LSPR) enhanced photocatalysis has fascinated much interest and considerable efforts have been devoted toward the development of plasmonic photocatalysts. In the past decades, noble metal nanoparticles (Au and Ag) with LSPR feature have found wide applications in solar energy conversion. Numerous metal-based photocatalysts have been proposed including metal/semiconductor heterostructures and plasmonic bimetallic or multimetallic nanostructures. However, high cost and scarce reserve of noble metals largely limit their further practical use, which drives the focus gradually shift to low-cost and abundant nonmetallic nanostructures. Recently, various heavily doped semiconductors (such as WO3-x, MoO3-x, Cu2-xS, TiN) have emerged as potential alternatives to costly noble metals for efficient photocatalysis due to their strong LSPR property in visible-near infrared region. This review starts with a brief introduction to LSPR property and LSPR-enhanced photocatalysis, the following highlights recent advances of plasmonic photocatalysts from noble metal to semiconductor-based plasmonic nanostructures. Their synthesis methods and promising applicability in plasmon-driven photocatalytic reactions such as water splitting, CO2 reduction and pollution decomposition are also summarized in details. This review is expected to give guidelines for exploring more efficient plasmonic systems and provide a perspective on development of plasmonic photocatalysis.
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