Abstract
Electrochemical CO
2
reduction reaction (CO
2
RR) to liquid fuels is currently challenged by low product concentrations, as well as their mixture with traditional liquid electrolytes, such ...as KHCO
3
solution. Here we report an all-solid-state electrochemical CO
2
RR system for continuous generation of high-purity and high-concentration formic acid vapors and solutions. The cathode and anode were separated by a porous solid electrolyte (PSE) layer, where electrochemically generated formate and proton were recombined to form molecular formic acid. The generated formic acid can be efficiently removed in the form of vapors via inert gas stream flowing through the PSE layer. Coupling with a high activity (formate partial current densities ~450 mA cm
−2
), selectivity (maximal Faradaic efficiency ~97%), and stability (100 hours) grain boundary-enriched bismuth catalyst, we demonstrated ultra-high concentrations of pure formic acid solutions (up to nearly 100 wt.%) condensed from generated vapors via flexible tuning of the carrier gas stream.
Electrochemically converting nitrate, a widespread water pollutant, back to valuable ammonia is a green and delocalized route for ammonia synthesis, and can be an appealing and supplementary ...alternative to the Haber-Bosch process. However, as there are other nitrate reduction pathways present, selectively guiding the reaction pathway towards ammonia is currently challenged by the lack of efficient catalysts. Here we report a selective and active nitrate reduction to ammonia on Fe single atom catalyst, with a maximal ammonia Faradaic efficiency of ~ 75% and a yield rate of up to ~ 20,000 μg h
mg
(0.46 mmol h
cm
). Our Fe single atom catalyst can effectively prevent the N-N coupling step required for N
due to the lack of neighboring metal sites, promoting ammonia product selectivity. Density functional theory calculations reveal the reaction mechanisms and the potential limiting steps for nitrate reduction on atomically dispersed Fe sites.
Abstract
Oxygen reduction reaction towards hydrogen peroxide (H
2
O
2
) provides a green alternative route for H
2
O
2
production, but it lacks efficient catalysts to achieve high selectivity and ...activity simultaneously under industrial-relevant production rates. Here we report a boron-doped carbon (B-C) catalyst which can overcome this activity-selectivity dilemma. Compared to the state-of-the-art oxidized carbon catalyst, B-C catalyst presents enhanced activity (saving more than 210 mV overpotential) under industrial-relevant currents (up to 300 mA cm
−2
) while maintaining high H
2
O
2
selectivity (85–90%). Density-functional theory calculations reveal that the boron dopant site is responsible for high H
2
O
2
activity and selectivity due to low thermodynamic and kinetic barriers. Employed in our porous solid electrolyte reactor, the B-C catalyst demonstrates a direct and continuous generation of pure H
2
O
2
solutions with high selectivity (up to 95%) and high H
2
O
2
partial currents (up to ~400 mA cm
−2
), illustrating the catalyst’s great potential for practical applications in the future.
Cost‐effective aqueous rechargeable batteries are attractive alternatives to non‐aqueous cells for stationary grid energy storage. Among different aqueous cells, zinc‐ion batteries (ZIBs), based on ...Zn2+ intercalation chemistry, stand out as they can employ high‐capacity Zn metal as the anode material. Herein, we report a layered calcium vanadium oxide bronze as the cathode material for aqueous Zn batteries. For the storage of the Zn2+ ions in the aqueous electrolyte, we demonstrate that the calcium‐based bronze structure can deliver a high capacity of 340 mA h g−1 at 0.2 C, good rate capability, and very long cycling life (96 % retention after 3000 cycles at 80 C). Further, we investigate the Zn2+ storage mechanism, and the corresponding electrochemical kinetics in this bronze cathode. Finally, we show that our Zn cell delivers an energy density of 267 W h kg−1 at a power density of 53.4 W kg−1.
A new cathode material, layered calcium vanadium oxide bronze, was synthesized for aqueous zinc‐ion battery applications. The calcium‐based bronze shows promising performance for storage of Zn2+ ions from the aqueous electrolyte (see picture). The Zn cell delivers an energy density of 267 W h kg−1 at a power density of 53.4 W kg−1.
A facile one-step electrodeposition method is developed to prepare ternary nickel cobalt sulfide interconnected nanosheet arrays on conductive carbon substrates as electrodes for supercapacitors, ...resulting in exceptional energy storage performance. Taking advantages of the highly conductive, mesoporous nature of the nanosheets and open framework of the three-dimensional nanoarchitectures, the ternary sulfide electrodes exhibit high specific capacitance (1418 F g–1 at 5 A g–1 and 1285 F g–1 at 100 A g–1) with excellent rate capability. An asymmetric supercapacitor fabricated by the ternary sulfide nanosheet arrays as positive electrode and porous graphene film as negative electrode demonstrates outstanding electrochemical performance for practical energy storage applications. Our asymmetric supercapacitors show a high energy density of 60 Wh kg–1 at a power density of 1.8 kW kg–1. Even when charging the cell within 4.5 s, the energy density is still as high as 33 Wh kg–1 at an outstanding power density of 28.8 kW kg–1 with robust long-term cycling stability up to 50 000 cycles.
The increasing global demand for energy and the potential environmental impact of increased energy consumption require greener, safer, and more cost-efficient energy storage technologies. Lithium-ion ...batteries (LIBs) have been successful in meeting much of today’s energy storage demand; however, lithium (Li) is a costly metal, is unevenly distributed around the world, and poses serious safety and environmental concerns. Alternate battery technologies should thus be developed. Zinc-ion batteries (ZIBs) have recently attracted attention due to their safety, environmental friendliness, and lower cost, compared to LIBs. They use aqueous electrolytes, which give them an advantage over multivalent ion batteries (e.g., Mg2+, Ca2+, Al3+) that require more complex electrolytes. However, as with every new technology, many fundamental and practical challenges must be overcome for ZIBs to become commercial products. In this manuscript, we present a timely review and offer perspectives on recent developments and future directions in ZIBs research. The review is divided into five parts: (i) cathode material development, including an understanding of their reaction mechanism; (ii) electrolyte development and characterization; (iii) zinc anode, current collector, and separator design; (iv) applications; and (v) outlook and perspective.
Background and Aims
Cancer‐associated fibroblasts (CAFs) are key players in multicellular, stromal‐dependent alterations leading to HCC pathogenesis. However, the intricate crosstalk between CAFs and ...other components in the tumor microenvironment (TME) remains unclear. This study aimed to investigate the cellular crosstalk among CAFs, tumor cells, and tumor‐associated neutrophils (TANs) during different stages of HCC pathogenesis.
Approach and Results
In the HCC‐TME, CAF‐derived cardiotrophin‐like cytokine factor 1 (CLCF1) increased chemokine (C‐X‐C motif) ligand 6 (CXCL6) and TGF‐β secretion in tumor cells, which subsequently promoted tumor cell stemness in an autocrine manner and TAN infiltration and polarization in a paracrine manner. Moreover, CXCL6 and TGF‐β secreted by HCC cells activated extracellular signal‐regulated kinase (ERK) 1/2 signaling of CAFs to produce more CLCF1, thus forming a positive feedback loop to accelerate HCC progression. Inhibition of ERK1/2 or CLCF1/ciliary neurotrophic factor receptor signaling efficiently impaired CLCF1‐mediated crosstalk among CAFs, tumor cells, and TANs both in vitro and in vivo. In clinical samples, up‐regulation of the CLCF1−CXCL6/TGF‐β axis exhibited a marked correlation with increased cancer stem cells, “N2”‐polarized TANs, tumor stage, and poor prognosis.
Conclusions
This study reveals a cytokine‐mediated cellular crosstalk and clinical network involving the CLCF1−CXCL6/TGF‐β axis, which regulates the positive feedback loop among CAFs, tumor stemness, and TANs, HCC progression, and patient prognosis. These results may support the CLCF1 cascade as a potential prognostic biomarker and suggest that selective blockade of CLCF1/ciliary neurotrophic factor receptor or ERK1/2 signaling could provide an effective therapeutic target for patients with HCC.
Abstract
Electrochemical water oxidation reaction (WOR) to hydrogen peroxide (H
2
O
2
) via a 2e
−
pathway provides a sustainable H
2
O
2
synthetic route, but is challenged by the traditional 4e
−
...counterpart of oxygen evolution. Here we report a CO
2
/carbonate mediation approach to steering the WOR pathway from 4e
−
to 2e
−
. Using fluorine-doped tin oxide electrode in carbonate solutions, we achieved high H
2
O
2
selectivity of up to 87%, and delivered unprecedented H
2
O
2
partial currents of up to 1.3 A cm
−2
, which represents orders of magnitude improvement compared to literature. Molecular dynamics simulations, coupled with electron paramagnetic resonance and isotope labeling experiments, suggested that carbonate mediates the WOR pathway to H
2
O
2
through the formation of carbonate radical and percarbonate intermediates. The high selectivity, industrial-relevant activity, and good durability open up practical opportunities for delocalized H
2
O
2
production.
In this work, a microwave approach is developed to rapidly synthesize ultralong zinc pyrovanadate (Zn3V2O7(OH)2·2H2O, ZVO) nanowires with a porous crystal framework. It is shown that our synthesis ...strategy can easily be extended to fabricate other metal pyrovanadate compounds. The zinc pyrovanadate nanowires show significantly improved electrochemical performance when used as intercalation cathode for aqueous zinc–ion battery. Specifically, the ZVO cathode delivers high capacities of 213 and 76 mA h g−1 at current densities of 50 and 3000 mA g−1, respectively. Furthermore, the Zn//ZVO cells show good cycling stability up to 300 cycles. The estimated energy density of this Zn cell is ≈214Wh kg−1, which is much higher than commercial lead–acid batteries. Significant insight into the Zn‐storage mechanism in the pyrovanadate cathodes is presented using multiple analytical methods. In addition, it is shown that our prototype device can power a 1.5 V temperature sensor for at least 24 h.
Porous framework zinc pyrovanadate (Zn3V2O7(OH)2·2H3O, ZVO) nanowires are rapidly synthesized using a novel microwave technique. When used as a cathode for an aqueous zinc–ion battery, it is demonstrated that the ZVO cathode can deliver high capacities of 213 and 76 mA h g−1 at current densities of 50 and 3000 mA g−1, respectively.
A
bstract
Formation and evolution of topological defects in course of non-equilibrium symmetry breaking phase transitions is of wide interest in many areas of physics, from cosmology through ...condensed matter to low temperature physics. Its study in strongly coupled systems, in absence of quasiparticles, is especially challenging. We investigate breaking of U(1) symmetry and the resulting spontaneous formation of vortices in a (2 + 1)-dimensional holographic superconductor employing gauge/gravity duality, a ‘first-principles’ approach to study strongly coupled systems. Magnetic fluxons with quantized fluxes are seen emerging in the post-transition superconducting phase. As expected in type II superconductors, they are trapped in the cores of the order parameter vortices. The dependence of the density of these topological defects on the quench time, the dispersion of the typical winding numbers, and the vortex-vortex correlations are consistent with predictions of the Kibble-Zurek mechanism.
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