Aqueous zinc metal batteries are appealing candidates for grid energy storage. However, the inadequate electrochemical reversibility of the zinc metal negative electrode inhibits the battery ...performance at the large-scale cell level. Here, we develop practical ampere-hour-scale aqueous Zn metal battery pouch cells by engineering the electrolyte solution. After identifying the proton reduction as the primary source of H
evolution during Zn metal electrodeposition, we design an electrolyte solution containing reverse micelle structures where sulfolane molecules constrain water in nanodomains to hinder proton reduction. Furthermore, we develop and validate an electrochemical testing protocol to comprehensively evaluate the cell's coulombic efficiency and zinc metal electrode cycle life. Finally, using the reverse micelle electrolyte, we assemble and test a practical ampere-hour Zn||Zn
V
O
•nH
O multi-layer pouch cell capable of delivering an initial energy density of 70 Wh L
(based on the volume of the cell components), capacity retention of about 80% after 390 cycles at 56 mA g
and ~25 °C and prolonged cycling for 5 months at 56 mA g
and ~25 °C.
Development of high‐performance and low‐cost nonprecious metal electrocatalysts is critical for eco‐friendly hydrogen production through electrolysis. Herein, a novel nanoflower‐like electrocatalyst ...comprising few‐layer nitrogen‐doped graphene‐encapsulated nickel–copper alloy directly on a porous nitrogen‐doped graphic carbon framework (denoted as Nix
Cuy
@ NG‐NC) is successfully synthesized using a facile and scalable method through calcinating the carbon, copper, and nickel hydroxy carbonate composite under inert atmosphere. The introduction of Cu can effectively modulate the morphologies and hydrogen evolution reaction (HER) performance. Moreover, the calcination temperature is an important factor to tune the thickness of graphene layers of the Nix
Cuy
@ NG‐NC composites and the associated electrocatalytic performance. Due to the collective effects including unique porous flowered architecture and the synergetic effect between the bimetallic alloy core and graphene shell, the Ni3Cu1@ NG‐NC electrocatalyst obtained under optimized conditions exhibits highly efficient and ultrastable activity toward HER in harsh environments, i.e., a low overpotential of 122 mV to achieve a current density of 10 mA cm−2 with a low Tafel slope of 84.2 mV dec−1 in alkaline media, and a low overpotential of 95 mV to achieve a current density of 10 mA cm−2 with a low Tafel slope of 77.1 mV dec−1 in acidic electrolyte.
A novel nanoflower‐like electrocatalyst comprising few‐layer nitrogen‐doped graphene‐encapsulated nickel–copper alloy on a porous nitrogen‐doped graphic carbon framework is synthesized by a facile and scalable method, and exhibits high activity and excellent stability for hydrogen evolution due to the collective effects, including unique porous flowered architecture and the synergetic effect between the bimetallic alloy core and the graphene shell.
Li–S batteries present great potential to realize high-energy-density storage, but their practical implementation is severely hampered by the notorious polysulfide shuttling and the sluggish redox ...kinetics. While rationally designed redox mediators can optimize polysulfide conversion, the efficiency and stability of such a mediation process still remain formidable challenges. Herein, a strategy of constructing a “dual mediator system” is proposed for achieving efficient and durable modulation of polysulfide conversion kinetics by coupling well-selected solid and electrolyte-soluble mediators. Theoretical prediction and detailed electrochemical analysis reveal the structure–activity relationships of the two mediators in synergistically optimizing the redox conversions of sulfur species, thus achieving a deeper mechanistic understanding of a function-supporting mediator system design toward sulfur electrochemistry promotion. Specifically, such a dual mediator system realizes the bridging of full-range “electrochemical catalysis” and strengthened “chemical reduction” processes of sulfur species as well as greatly suppressed mediator deactivation/loss due to the beneficial interactions between each mediator component. Attributed to these advantageous features, the Li–S batteries enable a slow capacity decay of 0.026% per cycle over 1200 cycles and a desirable capacity of 8.8 mAh cm–2 with 8.2 mg cm–2 sulfur loading and lean electrolyte condition. This work not only proposes an effective mediator system design strategy for promoting Li–S battery performance but also inspires its potential utilization facing other analogous sophisticated electrochemical conversion processes.
Metallic phthalocyanines (MePcs) have shown their potential as catalysts for CO2 reduction reactions (CO2RR). However, their low conductivity, easy agglomeration, and poor stability enslave the ...further progress of their CO2RR applications. Herein, an integrated heterogeneous molecular catalyst through anchoring CoPc molecules on 3D nitrogen‐doped vertical graphene arrays (NVG) on carbon cloth (CC) is reported. The CoPc‐NVG/CC electrodes exhibit superior performance for reducing CO2 to CO with a Faradic efficiency of above 97.5% over a wide potential range (99% at an optimal potential), a very high turnover frequency of 35800 h−1, and decent stability. It is revealed that NVG interacts with CoPc to form highly efficient channels for electron transfer from NVG to CoPc, facilitating the Co(II)/Co(I) redox of CO2 reduction. The strong coupling effect between NVG and CoPc molecules not only endows CoPc with high intrinsic activity for CO2RR, but also enhances the stability of electrocatalysts under high potentials. This work paves an efficient approach for developing high‐performance heterogeneous catalysts by using rationally designed 3D integrated graphene arrays to host molecular metallic phthalocyanines so as to ameliorate their electronic structures and engineer stable active sites.
Three‐dimensional nitrogen‐doped vertical graphene arrays (NVG) are designed and utilized as scaffolds to anchor highly dispersed CoPc molecules to obtain an integrated heterogeneous molecular catalyst (CoPc‐NVG/CC). The strong coupling effect between NVG with CoPc not only endows CoPc with high intrinsic activity for CO2RR but also enhances the stability of electrocatalysts under high potentials.
Metallic phthalocyanines (MePcs) have shown their potential as catalysts for CO
reduction reactions (CO
RR). However, their low conductivity, easy agglomeration, and poor stability enslave the ...further progress of their CO
RR applications. Herein, an integrated heterogeneous molecular catalyst through anchoring CoPc molecules on 3D nitrogen-doped vertical graphene arrays (NVG) on carbon cloth (CC) is reported. The CoPc-NVG/CC electrodes exhibit superior performance for reducing CO
to CO with a Faradic efficiency of above 97.5% over a wide potential range (99% at an optimal potential), a very high turnover frequency of 35800 h
, and decent stability. It is revealed that NVG interacts with CoPc to form highly efficient channels for electron transfer from NVG to CoPc, facilitating the Co(II)/Co(I) redox of CO
reduction. The strong coupling effect between NVG and CoPc molecules not only endows CoPc with high intrinsic activity for CO
RR, but also enhances the stability of electrocatalysts under high potentials. This work paves an efficient approach for developing high-performance heterogeneous catalysts by using rationally designed 3D integrated graphene arrays to host molecular metallic phthalocyanines so as to ameliorate their electronic structures and engineer stable active sites.
Single‐atom catalysts (SACs) have received widespread interest for their high atomic efficiency, enriched active sites, excellent catalytic performance, and low cost. However, the agglomeration of ...single metal atoms and the use of inactive additives for affixing powdery SACs on planar electrodes may reduce the density of active sites, diminish the charge transport to active sites, and thus suppress their performance. Herein, a series of metal–nitrogen–carbon single‐atom aerogels (M‐SAAs, M: Cu, Ni, Au, Ru) are synthesized via a universal strategy, in which the merits of metal organic frameworks and carbon aerogels are perfectly combined to prevent the agglomeration of single metal atoms and overcome the problem of poor electrical conductivity. The as‐prepared M‐SAAs can be directly employed as self‐supporting electrodes for the electrochemical dechlorination of 1,2‐dichloroethane, and outstanding activity and stability are observed. Significantly, the Cu‐SAA with abundant Cu−N4 sites shows an extraordinarily high ethylene production rate of 446 µmol h−1, with a selectivity of 99% and Faradaic efficiency of 64%. Moreover, theoretical calculations are performed to demonstrate the selectivity and activity of different metal active sites. This study provides a new strategy to exploit highly effective SACs and offers an intensive insight into the mechanism of electrochemical dechlorination reactions.
A series of metal–nitrogen–carbon single‐atom aerogels are developed via a new strategy and employed as self‐supporting electrodes for the electrochemical dechlorination of 1,2‐dichloroethane. The strategy can not only prevent the agglomeration of metal atoms, but also overcome the poor electrical conductivity caused by the binder. Therefore, the electrodes show outstanding performance with high ethylene production rate, selectivity, and Faradaic efficiency.
The rational design of high-performance electrocatalysts based on nonprecious metals is a key for the development of water-splitting technology. In this work, porous nickel-cobalt nitride–oxide ...(NiCo–N–O) nanosheet hybrids in a networked configuration are synthesized on carbon cloth through in situ plasma treatment of nickel-cobalt layered double hydroxide (LDH) precursors. The self-supported NiCo–N–O electrodes exhibit the outstanding catalytic activity of hydrogen evolution reaction (HER) with a low overpotential of 50 mV at 10 mA cm−2 in alkaline conditions. The synergistic effects of the morphology, microstructure, and electron transfer between nickel-cobalt nitride and oxide and the favorable role of introducing bimetallic Ni and Co sites on the enhanced electrocatalytic activities are discussed. This work provides a simple and feasible pathway to prepare porous bimetal nitride–oxide hybrid HER electrocatalysts with high efficiency and stability.
Display omitted
•Porous nickel-cobalt nitride–oxide (NiCo–N–O) hybrids are synthesized through in situ plasma treatment of LDH precursors.•Self-supported NiCo-N-O electrode delivers superior performance and favorable stability of HER.•The synergistic effects of the morphology, microstructure, and electron transfer between nickel cobalt nitride and oxide are discussed.
Acute myeloid leukemia (AML) is a highly heterogenous cancer in hematopoiesis, and its subtype specification is greatly important in the clinical practice for AML diagnosis and prognosis. Increasing ...evidence has shown the association between microRNA (miRNA) phenotype and AML therapeutic outcomes, emphasizing the need for novel techniques for convenient, sensitive, and efficient miRNA profiling in clinical practices. Here, we describe a nanoneedle-based discrete single-cell microRNA profiling technique for multiplexed phenotyping of AML heterogeneity without the requirement of sequencing or polymerase chain reaction (PCR). In virtue of a biochip-based and non-destructive nature of the assay, the expression of nine miRNAs in large number of living AML cells can be simultaneously analyzed with discrete single-cell level information, thus providing a proof-of-concept demonstration of an AML subtype classifier based on the multidimensional miRNA data. We showed successful analysis of subtype-specific cellular composition with over 90% accuracy and identified drug-responsive leukemia subpopulations among a mixed suspension of cells modeling different AML subtypes. The adoption of machine learning algorithms for processing the large-scale nanoneedle-based miRNA data shows the potential for powerful prediction capability in clinical applications to assist therapeutic decisions. We believe that this platform provides an efficient and cost-effective solution to move forward the translational prognostic usage of miRNAs in AML treatment and can be readily and advantageously applied in analyzing rare patient-derived clinical samples.
Synthesis of highly-efficiency electrocatalysts with controllable morphology, enriched active sites, and low cost is of great significance for urea oxidation reaction (UOR) applications. In this ...work, novel two-dimensional (2D) nickel-based metal-organic framework (Ni-MOF) nanosheets comprising Ni2+ and an organic ligand of 4-Dimethylaminopyridine (Ni-DMAP-t, where t is the synthesis time) are firstly synthesized by a facile one-pot solvothermal method. By thickness regulation of Ni-DMAP-t nanosheets, the self-supported Ni-DMAP-2 with the smallest thickness on Ni foam (Ni-DMAP-2/NF) exhibits high electrocatalytic activity toward UOR with a low potential of 1.45 V at a current density of 100 mA cm−2. Moreover, by further coupling with the cathodic hydrogen evolution reaction, the urea-assisted electrolytic hydrogen production system using Ni-DMAP-2/NF as anode displays a dramatic voltage reduction by 290 mV at a current density of 50 mA cm−2 as compared with that of conventional water electrolysis using the same electrodes. Such a superior UOR electrocatalytic activity of Ni-DMAP-2/NF is ascribed to the abundant Ni active sites exposed on the surface of Ni-DMAP-2, as well as the accelerated electron/ion transfer properties endowed by its ultrathin 2D nanosheets structure. This work offers some new ideas into the design and development of ultrathin 2D Ni-based MOF electrocatalysts for urea-related energy storage devices.
Display omitted
•Ni-MOFs comprising Ni2+ and 4-Dimethylaminopyridine are firstly synthesized.•The Ni-DMAP-2 with the smallest thickness shows remarkable UOR activity.•A urea-assisted H2 production with reduced cell voltage is constructed.
