Rationally designing active and durable catalysts for the oxygen evolution reaction (OER) is of primary importance in water splitting. Perovskite oxides (ABO3) with versatile structures and multiple ...physicochemical properties have triggered considerable interest in the OER. The leaching of A site cations can create nanostructures and amorphous motifs on the perovskite matrix, thus facilitating the OER process. However, selectively dissolving A site cations and simultaneously obtaining more active amorphous motifs derived from the B site cations remains a great challenge. Herein, a top‐down strategy is proposed to transform bulk crystalline perovskite (LaNiO3) into a nanostructured amorphous hydroxide by FeCl3 post‐treatment, resulting in an extremely low overpotential of 189 mV at 10 mA cm−2. The top‐down‐constructed amorphous catalyst with a large surface area has dual NiFe active sites, where high‐valence Ni3+‐based edge‐sharing octahedral frameworks are surrounded by interstitial distorted Fe octahedra and contribute to the superior OER performance. This top‐down strategy provides a valid way to design novel perovskite‐derived catalysts.
An amorphous NiFe‐based catalyst (a‐LNF(t‐d)) is constructed from LaNiO3 perovskite oxide through a top‐down strategy involving FeCl3 post‐treatment, which selectively dissolves the La ions and deposits the Fe ions. The a‐LNF(t‐d) sample, with large surface area and unusual electronic/geometrical structure shows extremely high oxygen evolution reaction (OER) activity and stability.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Developing efficient and low‐cost electrocatalysts for the oxygen evolution reaction (OER) is of paramount importance to many chemical and energy transformation technologies. The diversity and ...flexibility of metal oxides offer numerous degrees of freedom for enhancing catalytic activity by tailoring their physicochemical properties, but the active site of current metal oxides for OER is still limited to either metal ions or lattice oxygen. Here, a new complex oxide with unique hexagonal structure consisting of one honeycomb‐like network, Ba4Sr4(Co0.8Fe0.2)4O15 (hex‐BSCF), is reported, demonstrating ultrahigh OER activity because both the tetrahedral Co ions and the octahedral oxygen ions on the surface are active, as confirmed by combined X‐ray absorption spectroscopy analysis and theoretical calculations. The bulk hex‐BSCF material synthesized by the facile and scalable sol–gel method achieves 10 mA cm−2 at a low overpotential of only 340 mV (and small Tafel slope of 47 mV dec−1) in 0.1 m KOH, surpassing most metal oxides ever reported for OER, while maintaining excellent durability. This study opens up a new avenue to dramatically enhancing catalytic activity of metal oxides for other applications through rational design of structures with multiple active sites.
A new complex oxide with unique hexagonal structure consisting of one ordered (Co/Fe)O15 cluster, Ba4Sr4(Co0.8Fe0.2)4O15 (hex‐BSCF), is reported to show ultrahigh oxygen evolution reaction (OER) electrocatalytic activity because both the tetrahedral Co ions and the octahedral oxygen ions on the surface are active, as confirmed by combined X‐ray absorption spectroscopy analysis and theoretical calculations.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Reversible post-translational modifications represent a mechanism to control tumor metabolism. Here we show that mitochondrial Sirtuin5 (SIRT5), which mediates lysine desuccinylation, ...deglutarylation, and demalonylation, plays a role in colorectal cancer (CRC) glutamine metabolic rewiring. Metabolic profiling identifies that deletion of SIRT5 causes a marked decrease in
C-glutamine incorporation into tricarboxylic-acid (TCA) cycle intermediates and glutamine-derived non-essential amino acids. This reduces the building blocks required for rapid growth. Mechanistically, the direct interaction between SIRT5 and glutamate dehydrogenase 1 (GLUD1) causes deglutarylation and functional activation of GLUD1, a critical regulator of cellular glutaminolysis. Consistently, GLUD1 knockdown diminishes SIRT5-induced proliferation, both in vivo and in vitro. Clinically, overexpression of SIRT5 is significantly correlated with poor prognosis in CRC. Thus, SIRT5 supports the anaplerotic entry of glutamine into the TCA cycle in malignant phenotypes of CRC via activating GLUD1.
Abstract
The state-of-the-art active HER catalysts in acid media (e.g., Pt) generally lose considerable catalytic performance in alkaline media mainly due to the additional water dissociation step. ...To address this issue, synergistic hybrid catalysts are always designed by coupling them with metal (hydro)oxides. However, such hybrid systems usually suffer from long reaction path, high cost and complex preparation methods. Here, we discover a single-phase HER catalyst, SrTi
0.7
Ru
0.3
O
3-δ
(STRO) perovskite oxide highlighted with an unusual super-exchange effect, which exhibits excellent HER performance in alkaline media via atomic-scale synergistic active centers. With insights from first-principles calculations, the intrinsically synergistic interplays between multiple active centers in STRO are uncovered to accurately catalyze different elementary steps of alkaline HER; namely, the Ti sites facilitates nearly-barrierless water dissociation, Ru sites function favorably for OH* desorption, and non-metal oxygen sites (i.e., oxygen vacancies/lattice oxygen) promotes optimal H* adsorption and H
2
desorption.
Gemcitabine (GEM) resistance in pancreatic adenocarcinoma mediated by the receptor for advanced glycation end products (RAGE) has been demonstrated. Therefore, investigating the safety and the ...potential of new auxiliary methods for pancreatic cancer treatment is urgent. Ursolic acid (UA), a natural pentacyclic triterpenoid found in apple peels, rosemary, and thyme, has been reported to have anticancer capacity. This study aimed to reveal the underlying mechanisms of UA in cell death and drug enhancement, especially in GEM‐resistant pancreatic cancer cells. First, GEM‐resistant cells (MIA Paca‐2GEMR cells) were established by incrementally increasing GEM culture concentrations. UA treatment reduced cell viability through cell cycle arrest and endoplasmic reticulum (ER) stress, resulting in apoptosis and autophagy in a dose‐dependent manner in MIA Paca‐2 and MIA Paca‐2GEMR cells. High RAGE expression in MIA Paca‐2GEMR cells was suppressed by UA treatment. Interestingly, knocking down RAGE expression showed similar UA‐induced effects in both cell lines. Remarkably, UA had a drug‐enhancing effect by decreasing cell viability and increasing cell cytotoxicity when combined with GEM treatment. In conclusions, UA triggered ER stress, subsequently regulating apoptosis‐ and autophagy‐related pathways and increasing GEM chemosensitivity in pancreatic cancer cells by inhibiting the expression of RAGE.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The development of efficient bifunctional electrodes with extraordinary mass activity and robust stability is an eternal yet challenging goal for the water‐splitting process. Surface reconstruction ...during electrocatalysis can form fresh‐composition electrocatalysts with unusual amorphous phases in situ, which are more active but difficult to prepare by conventional methods. Here, a facile strategy based on fast reconstruction of amorphous nanofilm precursors is proposed for exploring precious‐metal‐free catalysts with good electronic conductivity, ultrahigh activity, and robust stability. As a proof of concept, an amorphous SrCo0.85Fe0.1P0.05O3−δ (SCFP) nanofilm precursor with weak chemical bonds deposited onto a conductive nickel foam (NF) substrate (SCFP‐NF) is synthesized by utilizing a high‐energy argon plasma to break the strong chemical bonds in a crystalline SCFP target. The quickly reconstructed SCFP‐NF bifunctional catalysts show ultrahigh mass activity of up to 1000 mA mg−1 at an overpotential of 550 mV and extremely long operational stability of up to 650 h at 10 mA cm−2, significantly overperforming state‐of‐the‐art precious‐metal catalysts. Such a strategy is further demonstrated to be a universal method, which can be applied to accelerate the reconstruction of other material systems to obtain various efficient electrocatalysts.
A universal strategy based on electrochemically induced fast reconstruction of amorphous nanofilm precursors is proposed for exploring ultrahigh mass activity and extremely stable bifunctional water‐splitting catalysts. The facile reconstruction strategy is promising for the development of novel efficient catalysts for other advanced energy conversion and storage devices.
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The ability to determine the electronic structure of catalysts during electrochemical reactions is highly important for identification of the active sites and the reaction mechanism. Here we ...successfully applied soft X-ray spectroscopy to follow in operando the valence and spin state of the Co ions in Li
Co
O
under oxygen evolution reaction (OER) conditions. We have observed that a substantial fraction of the Co ions undergo a voltage-dependent and time-dependent valence state transition from Co
to Co
accompanied by spontaneous delithiation, whereas the edge-shared Co-O network and spin state of the Co ions remain unchanged. Density functional theory calculations indicate that the highly oxidized Co
site, rather than the Co
site or the oxygen vacancy site, is mainly responsible for the high OER activity.
The oxygen evolution reaction (OER) is pivotal in multiple gas‐involved energy conversion technologies, such as water splitting, rechargeable metal–air batteries, and CO2/N2 electrolysis. Emerging ...anion‐redox chemistry provides exciting opportunities for boosting catalytic activity, and thus mastering lattice‐oxygen activation of metal oxides and identifying the origins are crucial for the development of advanced catalysts. Here, a strategy to activate surface lattice‐oxygen sites for OER catalysis via constructing a Ruddlesden–Popper/perovskite hybrid, which is prepared by a facile one‐pot self‐assembly method, is developed. As a proof‐of‐concept, the unique hybrid catalyst (RP/P‐LSCF) consists of a dominated Ruddlesden–Popper phase LaSr3Co1.5Fe1.5O10‐δ (RP‐LSCF) and second perovskite phase La0.25Sr0.75Co0.5Fe0.5O3‐δ (P‐LSCF), displaying exceptional OER activity. The RP/P‐LSCF achieves 10 mA cm−2 at a low overpotential of only 324 mV in 0.1 m KOH, surpassing the benchmark RuO2 and various state‐of‐the‐art metal oxides ever reported for OER, while showing significantly higher activity and stability than single RP‐LSCF oxide. The high catalytic performance for RP/P‐LSCF is attributed to the strong metal–oxygen covalency and high oxygen‐ion diffusion rate resulting from the phase mixture, which likely triggers the surface lattice‐oxygen activation to participate in OER. The success of Ruddlesden–Popper/perovskite hybrid construction creates a new direction to design advanced catalysts for various energy applications.
A hybrid (RP/P‐LSCF) consisting of a dominated Ruddlesden–Popper phase LaSr3Co1.5Fe1.5O10‐δ and second perovskite phase La0.25Sr0.75Co0.5Fe0.5O3‐δ, which is prepared by a facile one‐pot self‐assembly method, exhibits exceptional oxygen evolution reaction activity due to surface lattice‐oxygen activation triggered by strong metal–oxygen covalency and high oxygen‐ion diffusion rate.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Sluggish kinetics and poor reversibility of cathode chemistry is the major challenge for magnesium batteries to achieve high volumetric capacity. Introduction of the cuprous ion (Cu+) as a charge ...carrier can decouple the magnesiation related energy storage from the cathode electrochemistry. Cu+ is generated from a fast equilibrium between copper selenide electrode and Mg electrolyte during standing time, rather than in the electrochemical process. A reversible chemical magnesiation/de‐magnesiation can be driven by this solid/liquid equilibrium. During a typical discharge process, Cu+ is reduced to Cu and drives the equilibrium to promote the magnesiation process. The reversible Cu to Cu+ redox promotes the recharge process. This novel Cu+ mediated cathode chemistry of Mg battery leads to a high reversible areal capacity of 12.5 mAh cm−2 with high mass loading (49.1 mg cm−2) of the electrode. 80 % capacity retention can be achieved for 200 cycles after a conditioning process.
The right chemistry: A chemical, rather than electrochemical, magnesiation/de‐magnesiation process with the assistance of the Cu+ equilibrium is revealed. It guarantees fast charging/discharging processes and long‐term durability of rechargeable Mg batteries under practically high mass‐loading conditions.
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Abstract
The radius valley, a dip in the radius distribution of exoplanets at ∼1.9
R
⊕
, separates compact rocky super-Earths and sub-Neptunes with lower density. Various hypotheses have been put ...forward to explain the radius valley. Characterizing the radius valley morphology and its correlation to stellar properties will provide crucial observation constraints on its origin mechanism and deepen the understanding of planet formation and evolution. In this paper, the third part of the Planets Across Space and Time series, using the LAMOST-Gaia-Kepler catalog, we perform a systematical investigation into how the radius valley morphology varies in the Galactic context, i.e., thin/thick galactic disks, stellar age, and metallicity abundance (Fe/H and
α
/Fe). We find the following: (1) The valley becomes more prominent with the increase of both age and Fe/H. (2) The number ratio of super-Earths to sub-Neptunes monotonically increases with age but decreases with Fe/H and
α
/Fe. (3) The average radius of planets above the valley (2.1–6
R
⊕
) decreases with age but increases with Fe/H. (4) In contrast, the average radius of planets below the valley (
R
< 1.7
R
⊕
) is broadly independent of age and metallicity. Our results demonstrate that the valley morphology, as well as the whole planetary radius distribution, evolves on a long timescale of gigayears, and metallicities (not only Fe but also other metal elements, e.g., Mg, Si, Ca, Ti) play important roles in planet formation and in the long-term planetary evolution.
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