Latest ArticlesDeveloping high-efficiency, inexpensive, and steady non-precious metal oxygen reduction reaction (ORR) catalysts to displace Pt-based catalysts is significant for commercial applications of Al-air battery. Here, we have prepared the Cu/Cu2O-NC catalyst with excellent ORR performance and high stability, due to the synergistic effect of Cu and Cu2O nanoparticles. The half-wave potential (0.8 V) and the limiting-current density (5.20 mA/cm2) of the Cu/Cu2O-NC are very close to those of the 20% Pt/C catalyst (0.82 V, 5.10 mA/cm2). Besides, it exhibits excellent performance with a maximal power density of 250 mW/cm2 and a stable continuous discharge for more than 90 h in the Al-air battery test. The promoting effects of Cu2O towards Cu-based ORR catalysts are illustrated as follows: (i) Cu2O is the major ORR active site by the redox of Cu(Ⅱ)/Cu(Ⅰ), which provides excellent ORR activities; (ii) Cu can stabilize the location of Cu2O by assisting the electron transfer to Cu(Ⅱ)/Cu(Ⅰ) redox, which is conducive to the high stability of the catalyst. This work provides a useful strategy for enhancing the ORR performance of Cu-based catalysts.
In the crystal engineering area, it is important to clearly demonstrating the relationship of structure and certain functionality. Herein, we present the study of the relationship of structure with phosphorescent nature for two new room temperature phosphorescence (RTP) coordination polymers (CPs). [Pb(FDA)(H2O)] (1) and [NH3(CH3)NH2(CH3)2][Pb4(FDA)5] (2), where H2FDA is 2, 5-furandicarboxylic acid, have been synthesized by solvothermal method using different solvents and Pb2+ sources and characterized by microanalysis, powder X-ray diffraction (PXRD), thermogravimetric (TG), IR and UV–vis spectra. The Pb2+ ions adopt bicapped triangle prism coordination sphere in 1 and 2, which are connected together via FDA2− ligands into bilayer structure in 1 while pillared-layer framework in 2. The FDA2− ligands show different bridging modes in 1 and 2, leading to distinct coordination interactions between Pb2+ ion and FDA2− ligand in both CPs. Both 1 and 2 emit ligand-centered RTP due to the heavy atom of Pb2+ ion, with a lifetime and quantum yield of 0.62 ms and 14.9% in 1 versus 1.69 ms and 15.7% in 2. The emission peak shows significant redshift (79 nm) in 2 regarding 1, which arises from their distinction of coordination interactions between Pb2+ ion and FDA2− ligand in both CPs.
Environmental risks posed by discharge of the emerging contaminant antimony (Sb) into water bodies have raised global concerns recently. The toxicity of Sb has been shown to be species-dependent, with Sb(III) demonstrating much greater toxicity than Sb(V). Here, we proposed an electrochemical filtration system to achieve rapid detoxification of Sb(III) via a non-radical pathway. The key to this technology was an electroactive carbon nanotube filter functionalized with nanoscale Ti-Ce binary oxide. Under an electric field, in situ generated H2O2 could react with the Ti-Ce binary oxide to produce hydroperoxide complexes, which enabled an efficient transformation of Sb(III) to the less toxic Sb(V) (τ < 2 s) at neutral pH. The impact of important operational parameters was assessed and optimized, and system efficacy could be maintained over a wide pH range and long-term operation. An optimum detoxification efficiency of > 90% was achieved using lake water spiked with Sb(III) at 500 μg/L. The results showed that Ti/Ce-hydroperoxo surface complexes were the dominant species responsible for the non-radical oxidation of Sb(III) based on extensive experimental evidences and advanced characterizations. This study provides a robust and effective strategy for the detoxification of water containing Sb(III) and other similar heavy metal ions by integrating state-of-the-art advanced oxidation processes, electrochemistry and nano-filtration technology.
Fabrication of well-designed heterojunctions is an extraordinarily attractive pathway for boosting the photocatalytic activity toward CO2 photoreduction. Herein, a novel kind of nanosheet-based intercalation hybrid coupled with CdSe quantum dots (QDs) was successfully fabricated by a facile solvothermal method and served as photocatalyst for full-spectrum-light-driven CO2 reduction. Ultra-small CdSe QDs were rationally in-situ introduced and coupled with lamellar ZnSe-intercalation hybrid nanosheet, resulting in the formation of CdSe QDs/ZnSe hybrid heterojunction. Significantly, the concentration of Cd2+ could change directly the crystallinity and micromorphology of ZnSe intercalation hybrid, which in turn would impact on the photocatalysis activity. The optimized CdSe QDs/ZnSe hybrid-5 composite demonstrated a considerable CO yield rate of the 25.6 μmol g-1 h-1 without any additional cocatalysts or sacrificial agents assisting, making it one of the best reported performance toward CO2 photoreduction under full-spectrum light. The elevated CO2 photoreduction activity could be attributed to the special surface heterojunction, leading to improving the ability of light absorption and promoting the separation/transfer of photogenerated carriers. This present study developed a new strategy for designing inorganic-organic heterojunctions with enhanced photocatalyst for CO2 photoreduction and provided an available way to simultaneously mitigate the greenhouse effect and alleviate energy shortage pressure.
In power storage technology, ion exchange is widely used to modify the electronic structures of electrode materials to stimulate their electrochemical properties. Here, we proposed a multistep ion exchange (cation exchange and anion exchange) strategy to synthesize amorphous Ni-Co-S and β-Co(OH)2 hybrid nanomaterials with a hollow polyhedron structures. The synergistic effects of different components and the remarkable superiorities of hollow structure endow Ni-Co-S/Co(OH)2 electrode with outstanding electrochemical performance, including ultra-high specific capacity (1440.0 C/g at 1 A/g), superior capacitance retention rate (79.1% retention at 20 A/g) and long operating lifespan (81.4% retention after 5000 cycles). Moreover, the corresponding hybrid supercapacitor enjoys a high energy density of 58.4 Wh/kg at the power density of 0.8 kW/kg, and a decent cyclability that the capacitances are maintained at 80.8% compared with the initial capacitance. This research presents a high-performance electrode material and provides a promising route for the construction of electrode materials for supercapacitors with both structural and component advantages.
Li-O2 batteries (LOBs) have been perceived as the most potential clean energy system for fast-growing electric vehicles by reason of their environmentally friendlier, high energy density and high reversibility. However, there are still some issues limiting the practical application of LOBs, such as the large gap between the actual capacity level and the theoretical capacity, low rate performance as well as short cycle life. Herein, hollow CeO2/Co3O4 polyhedrons have been synthesized by MOF template with a simple method. And it is was further served as a cathode catalyst in Li-O2 batteries. By means of the synergistic effect of two different transition metal oxides, nano-sized hollow porous CeO2/Co3O4 cathode obtained better capacity and cycle performance. As a result, excellent cyclability of exceeding 140 and 90 cycles are achieved at a fixed capacity of 600 and 1000 mAh/g, respectively. The successful application of this catalyst in LOBs offers a novel route in the aspect of the synthesis of other hollow porous composite oxides as catalysts for cathodes in LOBs systems by the MOF template method.
Hydrogen sulfide (H2S) is a signaling molecule that plays important roles in biological systems. The exploration of H2S as a new drug release trigger and its related fluorescent theranostic system is crucial for cancer bio-imaging and therapy. Herein, we designed a new two-photon ratiometric fluorescent theranostic prodrug (compound 1) and studied its spectroscopic properties and application in in vivo imaging. Compound 1 specifically reacted with H2S and released the free active therapeutic component of 7-ethyl-10-hydroxycamptothecin, which was accompanied with a red-shift fluorescence emission signal from 460 nm to 545 nm. The exogenous and endogenous H2S in living cells were imaged by compound 1 under one-photon and two-photon excitation. Furthermore, compound 1 monitored the H2S concentration changes in Caenorhabditis elegans by fluorescence imaging. Additionally, it showed effective drug release activation in situ tumor with exogenous and endogenous H2S as the trigger. The H2S-sensitive activation and drug-release properties highlight the potential of theranostic compound 1 in future cancer treatment and therapy.
Electrochemical water splitting is a facile and effective route to generate pure hydrogen and oxygen. However, the sluggish kinetics of hydrogen evolution reaction (HER) and especially oxygen evolution reaction (OER) hinder the water splitting efficiency. Meanwhile, the high-cost of noble-metal catalysts limit their actual application. It is thus highly urgent to exploit an economical and earth-abundant bifunctional HER and OER electrocatalyst to simplify procedure and reduce cost. Herein, we synthesize the three-dimensionally ordered macro-/mesoporous (3DOM/m) NixCo100-x alloys with distinctive structure and large surface area via a dual-templating technique. Among them, the 3DOM/m Ni61Co39 shows the lowest overpotentials of 121 mV and 241 mV at 10 mA/cm2 for HER and OER, respectively. Furthermore, when employed for water splitting, the Ni61Co39 only requires 1.60 V to approach 10 mA/cm2 and presents excellent stability. These encouraging performances of the Ni61Co39 render it a promising bifunctional catalyst for overall water splitting.
Prussian whites (PWs) with a three-dimensional framework can accommodate the insertion and extraction of ions with large radius, which have been widely used in potassium ion batteries. However, PWs show the poor cycling performance and inferior rate ability because of high coordinated water. In this work, PWs with different water content were synthesized via a coprecipitation method by controlling the reaction temperature. The sample with low-coordination water prohibits the best electrochemical performance. It shows a high capacity of 120.5 mAh/g at 100 mA/g for potassium-ion batteries (KIBs). It also exhibits a good rate performance, displaying a capacity of 73.2 mAh/g at 500 mA/g.
Carbon nanofiber-based supercapacitors have broad prospects in powering wearable electronics owing to their high specific capacity, fast charge/discharge process, along with long-cycling life. Herein, a poly(acrylonitrile-co-β-methylhydrogen itaconate) copolymer was prepared and used to synthesize flexible hollow carbon nanofibers (HCNFs) via an electrospinning method without breaking after multiple bending. Subsequently, the inner and outer surfaces of HCNFs were evenly covered with ordered needle-like polyaniline (PANI) through in-situ polymerization methods to obtain three-dimensional flexible HCNFs/PANI composites, which exhibited a high capacity 1196.7 F/g at 1 A/g and good cycling stability (90.1% retention at 5 A/g after 3000 cycles). The symmetrical supercapacitor based on the HCNFs/PANI composites also delivered an outstanding electrochemical performance with high energy/power density (60.28 Wh/kg at 1000 W/kg) and superior cycling durability (90% capacitance retention after at 5 A/g 3000 cycles), which confirmed that the HCNFs/PANI composites had a wide application potential in flexible energy storage devices.
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