Calcium‐metal batteries (CMBs) provide a promising option for high‐energy and cost‐effective energy‐storage technology beyond the current state‐of‐the‐art lithium‐ion batteries. Nevertheless, the ...development of room‐temperature CMBs is significantly impeded by the poor reversibility and short lifespan of the calcium‐metal anode. A solvation manipulation strategy is reported to improve the plating/stripping reversibility of calcium‐metal anodes by enhancing the desolvation kinetics of calcium ions in the electrolyte. The introduction of lithium salt changes the electrolyte structure considerably by reducing coordination number of calcium ions in the first solvation shell. As a result, an unprecedented Coulombic efficiency of up to 99.1 % is achieved for galvanostatic plating/stripping of the calcium‐metal anode, accompanied by a very stable long‐term cycling performance over 200 cycles at room temperature. This work may open up new opportunities for development of practical CMBs.
Lithium salt added to the electrolyte of a calcium‐metal battery reduces the oxygen coordination number for the 43Ca nucleus in the first solvation shell, thereby promoting the desolvation kinetics of Ca2+ ions and the cycling performance of the calcium‐metal anode. Excellent reversibility of calcium plating and stripping is realized.
Nitrate can be electrochemically degraded to produce ammonia while treating sewage while it remains grand challenge to simultaneously realize high Faradaic efficiency and production rate over ...wide-range concentrations in real wastewater. Herein, we report the defect-rich Cu nanowire array electrode generated by in-situ electrochemical reduction, exhibiting superior performance in the electrochemical nitrate reduction reaction benefitting from the triple synergistic modulation. Notably, the defect-rich Cu nanowire array electrode delivers current density ranging from 50 to 1100 mA cm
across wide nitrate concentrations (1-100 mM) with Faradaic efficiency over 90%. Operando Synchrotron radiation Fourier Transform Infrared Spectroscopy and theoretical calculations revealed that the defective Cu sites can simultaneously enhance nitrate adsorption, promote water dissociation and suppress hydrogen evolution. A two-electrode system integrating nitrate reduction reaction in industrial wastewater with glycerol oxidation reaction achieves current density of 550 mA cm
at -1.4 V with 99.9% ammonia selectivity and 99.9% nitrate conversion with 100 h stability, demonstrating outstanding practicability.
A hybrid catalyst structure can provide abundant active sites and tailored electronic properties, but the major challenge lies in achieving delicate control over its composition and architecture to ...improve the catalytic activity toward different electrochemical reactions simultaneously. Herein, we present the rational design of a magic hybrid structure with low Pt loading (5.90 wt%), composed of CoPt3 and CoPt nanoparticles supported on N-doped carbon (CoPt3/CoPt⊂PLNC). Importantly, it shows superior multifunctional catalytic activity in alkaline conditions, requiring a low overpotential of 341 and 20 mV to achieve 10 mA cm−2 for the hydrazine oxidation reaction (HzOR)/hydrogen evolution reaction (HER), respectively, and it delivers a half-wave potential of 0.847 V for the oxygen reduction reaction (ORR). Theoretical calculations reveal that the metal–carbon hybrid modulates kinetic behavior and induces electron redistribution, achieving the energetic requirements for multiple electrocatalysis. We demonstrate sustainable H2 production utilizing solely the CoPt3/CoPt⊂PLNC catalyst, without external electric power input, suggesting its inspiring practical utility.
The featured nanohybrid structure displays highly efficient multifunctional electrocatalysis ability towards hydrazine electrolysis, oxygen reduction, and hydrogen evolution and fulfills the practical applications integrated with energy-saving H2 generation without external electricity input. Display omitted
•The delicate construction of a metal–carbon nanohybrid enhances electrocatalytic activity exceeding benchmark Pt/C.•Symbiotic CoPt and CoPt3 coupled with carbon enables excellent multifunctional electrocatalytic performance.•An integrated system for green H2 production without external electric power input is demonstrated.
Improving energy/fuel efficiency by converting waste heat into electricity using thermoelectric materials is of great interest due to its simplicity and reliability. However, many thermoelectric ...materials are composed of either toxic or scarce elements. Here, we report the experimental realization of using nontoxic and abundant copper zinc tin sulfide (CZTS) nanocrystals for potential thermoelectric applications. The CZTS nanocrystals can be synthesized in large quantities from solution phase reaction and compressed into robust bulk pellets through spark plasma sintering and hot press while still maintaining nanoscale grain size inside. Electrical and thermal measurements have been performed from 300 to 700 K to understand the electron and phonon transports. Extra copper doping during the nanocrystal synthesis introduces a significant improvement in the performance.
Tube in a tube: A general strategy for the fabrication of novel complex tube‐in‐tube nanostructures for many metal oxides has been developed. The method involves coating carbon nanofibers with a ...layer of metal glycolate followed by calcination in air. The unique complex tubular structures of metal oxides are shown to exhibit promising properties for the title applications.
Microstructure analysis indicates that Te/Bi core/shell nanowires are formed by a solution phase epitaxial growth process. The obtained Te/Bi core/shell nanowire composites possess a greatly enhanced ...Seebeck coefficient and a lowered thermal conductivity.
We present a design principle to develop new categories of telluride-based thermoelectric nanowire heterostructures through rational solution-phase reactions. The catalyst-free synthesis yields ...Te–Bi2Te3 “barbell” nanowire heterostructures with a narrow diameter and length distribution as well as a rough control over the density of the hexagonal Bi2Te3 plates on the Te nanowire bodies, which can be further converted to other telluride-based compositional-modulated nanowire heterostructures such as PbTe–Bi2Te3. Initial characterizations of the hot-pressed nanostructured bulk pellets of the Te–Bi2Te3 heterostructure show a largely enhanced Seebeck coefficient and greatly reduced thermal conductivity, which lead to an improved thermoelectric figure of merit. This approach opens up new platforms to investigate the phonon scattering and energy filtering.
P2‐type Na0.67Ni0.33Mn0.67O2 is considered as a potential cathode material for sodium‐ion batteries due to the merits of high voltage, low cost, and air stability. However, the unsatisfied cycling ...stability and rate performance caused by the destructive phase transition and side reactions hinder its practical application. Herein, we present a feasible dual strategy of Mg2+ doping integrated with ZrO2 surface modification for P2‐Na0.67Ni0.33Mn0.67O2, which can well address the issues of phase transition and side reactions benefitting from the enhanced structural and interfacial stabilities. Specifically, it exhibits a decent cycling stability with a capacity retention of 81.5% at 1 C and promising rate performance with a discharge capacity of 76.6 mA h g−1 at 5 C. The in situ X‐ray diffraction measurement confirms that the damaged P2–O2 phase transition is suppressed with better reversibility in high‐voltage region, whereas the side reactions are inhibited due to the protective ZrO2 surface modification. Commendably, the full cell achieves an outstanding operating voltage of 3.57 V and a fabulous energy density of 238.91 W h kg−1 at 36.73 W kg−1, demonstrating great practicability. This work is expected to provide a new insight for designing stable high‐voltage cathode materials and high energy density full cells for sodium ion batteries.
A dual strategy of Mg2+ doping integrated with ZrO2 surface modification is applied on P2‐Na0.67Ni0.33Mn0.67O2 to optimize its electrochemical performance. The damaged P2–O2 phase transition as well as side reactions between cathode and electrolyte are both suppressed after dual‐strategy modification, thus realizing stable high‐voltage cathode and high energy density full cell for sodium ion batteries.
Bismuth‐based electrocatalysts are promising candidates for electrochemical CO2 reduction to formate attributing to the accelerated formation of *OCHO intermediate, while the high‐energy consumption ...remains a major challenge for practicability. Herein, we present the ultrathin Bi2O2CO3 nanosheets with abundant oxygen vacancy (Vo‐BOC‐NS) reconstructed from S, N‐co‐doped bismuth oxides that can act as durable electrocatalyst for CO2‐to‐formate conversion with faradic efficiency (FEformate) of >95%, partial current density of 286 mA cm−2 with energy efficiency of 73.8% at −0.62 V (vs. RHE) and low overpotential of 200 mV in a flow electrolyzer. The theoretical calculations decipher that the oxygen vacancy can optimize *OCOH adsorption/desorption for the accelerated conversion kinetics. The pair‐electrosynthesis tactic of formate co‐production can enable a superior FEformate of >90% at wide cell voltage of 2–3.3 V and total yield rate of 3742 μmol cm−2 h−1 at 3.3 V, suggesting great potential for future industrialization.
Cathodic Bi‐based electrocatalyst with abundant oxygen vacancy displays highly efficient electrochemical CO2 reduction reaction (CRR) activity toward producing formate coupling with anodic methanol oxidation reaction (MOR), which provides an energy‐efficient and economic strategy for exclusively producing formate. The pair‐electrosynthesis tactic of formate co‐production can enable a superior FEformate of >90% at wide cell voltage of 2–3.3 V and total yield rate of 3742 μmol cm−2 h−1 at 3.3 V, suggesting great potential for future industrialization.
General synthesis of both binary and ternary V−VI based thermoelectric alloy hexagonal platelets was carried out for the first time in a unified system using a modified solvothermal method, which ...adopted convenient oxides as source materials and friendly ethylene glycol as both solvent and reducing agent. The structure and composition analysis reveal that the samples are pure phase with corresponding atomic ratios. Electron microscopy results indicate that the as-prepared products are uniform and highly crystallized. The formation process was studied in detail by observing time-dependent products, and it was found that the oriented attachment mechanism could be responsible for the growth of these hexagonal platelets, which exhibits intrinsic difference compared with the inferred seed-mediated growth mechanism in previous reports. The influence of pH value and polyvinyl pyrrolidone on the morphology of the products was investigated as well. This work may open up a new rationale on designing the solution synthesis of nanostructures for materials possessing similar intrinsic crystal symmetry.
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