We report a novel modulation strategy by introducing transition metals into NiS2 nanosheets (NSs) to flexibly optimize the electronic configurations and atomic arrangement. The Co‐NiS2 NSs exhibit ...excellent hydrogen evolution reaction (HER) performance with an overpotential of 80 mV at j=10 mA cm−2 and long‐term stability of 90 h in alkaline media. The turnover frequencies (TOFs) of 0.55 and 4.1 s−1 at an overpotential of 100 and 200 mV also confirm their remarkable performance. DFT calculations reveal that the surface dopants abnormally sensitize surface Ni‐3d bands in the long‐range order towards higher electron‐transfer activity, acting as the electron‐depletion center. Meanwhile, the high lying surface S‐sites possess substantially high selectivity for splitting the adsorbing H2O that guarantee the high HER performance within alkaline conditions. This work opens opportunities for enhancing water splitting by atomic‐arrangement‐assisted electronic modulation via a facile doping strategy.
Co doped: Cobalt‐doped NiS2 nanosheets (NSs) with optimal eg1 electron configurations and enhanced Ni3+ content exhibit excellent activity and stability for the hydrogen evolution reaction (HER) in alkaline media. DFT results reveal that a Co‐NiS2 NSs surface abnormally sensitizes Ni‐3d bands towards higher electron‐transfer.
Manipulating the active species and improving the structural stabilization of sulfur‐containing catalysts during the OER process remain a tremendous challenge. Herein, we constructed NiO/NiS2 and ...Fe−NiO/NiS2 as catalyst models to study the effect of Fe doping. As expected, Fe−NiO/NiS2 exhibits a low overpotential of 270 mV at 10 mA cm−2. The accumulation of hydroxyl groups on the surface of materials after Fe doping can promote the formation of highly active NiOOH at a lower OER potential. Moreover, we investigated the level of corrosion of M−S bonds and compared the stability variation of M−S bonds with Fe at different locations. Interestingly, Fe bonded with S in the bulk as the sacrificial agent can alleviate the oxidation corrosion of partial Ni−S bonds and thus endow Fe−NiO/NiS2 long‐term durability. This work could motivate the community to focus more on resolving the corrosion of sulfur‐containing materials.
Bulk doped Fe not only accelerates the surface reconstruction of NiO/NiS2 into the active NiOOH phase at a lower oxygen evolution reaction (OER) overpotential but also alleviates the oxidation corrosion of partial Ni−S bonds to provide a promising way to balance the activity and stability of sulfur‐containing materials in the OER process.
Owing to the unique electronic properties, rare‐earth modulations in noble‐metal electrocatalysts emerge as a critical strategy for a broad range of renewable energy solutions such as water‐splitting ...and metal–air batteries. Beyond the typical doping strategy that suffers from synthesis difficulties and concentration limitations, the innovative introduction of rare‐earth is highly desired. Herein, a novel synthesis strategy is presented by introducing CeO2 support for the nickel–iron–chromium hydroxide (NFC) to boost the oxygen evolution reaction (OER) performance, which achieves an ultralow overpotential at 10 mA cm−2 of 230.8 mV, the Tafel slope of 32.7 mV dec−1, as well as the excellent durability in alkaline solution. Density functional theory calculations prove the established d–f electronic ladders, by the interaction between NFC and CeO2, evidently boosts the high‐speed electron transfer. Meanwhile, the stable valence state in CeO2 preserves the high electronic reactivity for OER. This work demonstrates a promising approach in fabricating a nonprecious OER electrocatalyst with the facilitation of rare‐earth oxides to reach both excellent activity and high stability.
A novel and highly efficient hybrid electrocatalyst is synthesized by NiFeCr hydroxide deposited on a porous peapod‐like Cu@CeO2 nanotube array. The introduction of CeO2 supplies abundant d–f orbital ladders to construct a highly efficient electron transfer expressway, leading to superior alkaline oxygen evolution reaction performance.
The hydrogen evolution reaction (HER) usually has sluggish kinetics in alkaline solution due to the difficulty in forming binding protons. Herein we report an electrocatalyst in which sulfur atoms ...are doping in the oxygen vacancies (VO) of inverse spinel NiFe2O4 (S‐NiFe2O4) to create active sites with enhanced electron transfer capability. This electrocatalyst has an ultralow overpotential of 61 mV at the current density of 10 mA cm−2 and long‐term stability of 60 h at 1.0 Acm−2 in 1.0 M KOH media. In situ Raman spectroscopy revealed that S sites adsorb hydrogen adatom (H*) and in situ form S‐H*, which favor the production of hydrogen and boosts HER in alkaline solution. DFT calculations further verified that S introduction lowered the energy barrier of H2O dissociation. Both experimental and theoretical investigations confirmed S atoms are active sites of the S‐NiFe2O4.
Sulfur‐atom doping of inverse spinel NiFe2O4 results in the occupation of the oxygen vacancies. S sites in the S‐NiFe2O4 likely adsorb H adatoms and form S‐H* in situ, which boosts the hydrogen evolution reaction (HER) in alkaline solution. DFT calculations further verified that the lowered energy barrier for H2O dissociation induced by S doping is the key reason for the remarkable HER performance.
Structural engineering and compositional controlling are extensively applied in rationally designing and fabricating advanced freestanding electrocatalysts. The key relationship between the spatial ...distribution of components and enhanced electrocatalysis performance still needs further elaborate elucidation. Here, CeO2 substrate supported CoS1.97 (CeO2‐CoS1.97) and CoS1.97 with CeO2 surface decorated (CoS1.97‐CeO2) materials are constructed to comprehensively investigate the origin of spatial architectures for the oxygen evolution reaction (OER). CeO2‐CoS1.97 exhibits a low overpotential of 264 mV at 10 mA cm−2 due to the stable heterostructure and faster mass transfer. Meanwhile, CoS1.97‐CeO2 has a smaller Tafel slope of 49 mV dec−1 through enhanced adsorption of OH−, fast electron transfer, and in situ formation of Co(IV)O2 species under the OER condition. Furthermore, operando spectroscopic characterizations combined with theoretical calculations demonstrate that spatial architectures play a distinguished role in modulating the electronic structure and promoting the reconstruction from sulfide to oxyhydroxide toward higher chemical valence. The findings highlight spatial architectures and surface reconstruction in designing advanced electrocatalytic materials.
Two novel CeO2/CoS1.97 heterostructure electrocatalysts (CeO2‐CoS1.97 and CoS1.97‐CeO2) are constructed to investigate the relationships between spatial architectures and oxygen evolution reaction (OER) performances, where different configuration endows hybrids with distinct intermediate adsorption, modulated electronic structures, and promoted electrochemical reconstruction, thus improving the OER kinetics and performances. This work sheds light on the importance of rational design and synthesis of advanced hybrid electrocatalysts with functional spatial architectures.
The atroposelective synthesis of axially chiral styrenes remains a formidable challenge due to their relatively lower rotational barriers compared to the biaryl atropoisomers. Herein, we describe the ...construction of axially chiral styrenes through PdII‐catalyzed atroposelective C−H olefination, using a bulky amino amide as a transient chiral auxiliary. Various axially chiral styrenes were produced with good yields and high enantioselectivity (up to 95 % yield and 99 % ee). Carboxylic acid derivatives of the resulting axially chiral styrenes showed superior enantiocontrol over the biaryl counterparts in CoIII‐catalyzed enantioselective C(sp3)−H amidation of thioamide. Mechanistic studies suggest that C−H cleavage is the enantioselectivity‐determining step.
Axially chiral styrenes were constructed through a PdII‐catalyzed atroposelective C−H olefination with a bulky amino amide as a transient chiral auxiliary. Various axially chiral styrenes were produced with good yields and high enantioselectivity. Carboxylic acid derivatives of these axially chiral styrenes showed superior enantiocontrol compared to the biaryl counterparts in CoIII‐catalyzed enantioselective C(sp3)−H amidation of ferrocenes.
Layered double hydroxides (LDHs) have been considered as promising electrodes for supercapacitors due to their adjustable composition, designable function and superior high theoretic capacity. ...However, their experimental specific capacity is significantly lower than the theoretical value due to their small interlayer spacing. Therefore, obtaining large interlayer spacing through the intercalation of large‐sized anions is an important means to improve capacity performance. Herein, a metal organic framework derived cobalt‐nickel layered double hydroxide hollowcage intercalated with different concentrations of 1,4‐benzenedicarboxylic acid (H2BDC) through in‐situ cationic etching and organic ligand intercalation method is designed and fabricated. The superior specific capacity and excellent rate performance are benefit from the large specific surface area of the hollow structure and increasing interlayer spacing of LDH after H2BDC intercalation. The sample with the largest layer spacing displays a maximum specific capacity of 229 mA h g−1 at 1 A g−1. In addition, the hybrid supercapacitor assembled from the sample with the largest layer spacing and active carbon electrode has a maximum specific capacity of 158 mA h g−1 at 1 A g−1; the energy density is as high as 126.4 W h kg−1 at 800 W kg−1 and good cycle stability.
CoNi‐BDC hollowcage is obtained by intercalating H2BDC ligand into the CoNi‐LDH nanocage through in‐situ cationic etching and organic ligand intercalation methods for the first time. The structure design and engineering strategies of molecular layer spacing regulation endow larger specific surface areas and increase the interlayer spacing of CoNi‐LDH, thereby evidently boosting their electrochemical performance.
The proton exchange membrane (PEM) water electrolysis is one of the most promising hydrogen production techniques. The oxygen evolution reaction (OER) occurring at the anode dominates the overall ...efficiency. Developing active and robust electrocatalysts for OER in acid is a longstanding challenge for PEM water electrolyzers. Most catalysts show unsatisfied stability under strong acidic and oxidative conditions. Such a stability challenge also leads to difficulties for a better understanding of mechanisms. This review aims to provide the current progress on understanding of OER mechanisms in acid, analyze the promising strategies to enhance both activity and stability, and summarize the state‐of‐the‐art catalysts for OER in acid. First, the prevailing OER mechanisms are reviewed to establish the physicochemical structure–activity relationships for guiding the design of highly efficient OER electrocatalysts in acid with stable performance. The reported approaches to improve the activity, from macroview to microview, are then discussed. To analyze the problem of instability, the key factors affecting catalyst stability are summarized and the surface reconstruction is discussed. Various noble‐metal‐based OER catalysts and the current progress of non‐noble‐metal‐based catalysts are reviewed. Finally, the challenges and perspectives for the development of active and robust OER catalysts in acid are discussed.
Developing proton exchange membrane water electrolyzers requires a fundamental understanding of the oxygen evolution reaction (OER) in acid, which is the primary focus of this review. The water electrolyzer in alkaline and acid are compared; and the recent advances in OER mechanisms, the strategies for enhancing activity and stability of electrocatalysts, surface reconstruction, and the state‐of‐the‐art electrocatalysts are discussed.
Background and Aim
Coronavirus disease 2019 (COVID‐19) has attracted increasing worldwide attention. While diabetes is known to aggravate COVID‐19 severity, it is not known whether nondiabetic ...patients with metabolic dysfunction are also more prone to more severe disease. The association of metabolic associated fatty liver disease (MAFLD) with COVID‐19 severity in nondiabetic patients was investigated here.
Methods
The study cohort comprised 65 patients with (i.e. cases) and 65 patients without MAFLD (i.e. controls). Each case was randomly matched with one control by sex (1:1) and age (±5 years). The association between the presence of MAFLD (as exposure) and COVID‐19 severity (as the outcome) was assessed by binary logistic regression analysis.
Results
In nondiabetic patients with COVID‐19, the presence of MAFLD was associated with a four‐fold increased risk of severe COVID‐19; the risk increased with increasing numbers of metabolic risk factors. The association with COVID‐19 severity persisted after adjusting for age, sex, and coexisting morbid conditions.
Conclusion
Health‐care professionals caring for nondiabetic patients with COVID‐19 should be cognizant of the increased likelihood of severe COVID‐19 in patients with MAFLD.
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•Combined effects of MPs and BHA on zebrafish embryos/larvae were evaluated.•MPs promoted the accumulation of BHA in zebrafish larvae.•MPs enhanced the toxicity of BHA in larvae ...development.•Coexposure disturbed arachidonic acid, glycerophospholipid, and lipids metabolism.
Coexposure of MPs and other contaminants adsorbed from the environment has raised many attentions, but the understanding of the combined effects of MPs and plastic additives are limited. Butylated hydroxyanisole (BHA), a widely used synthetic phenolic antioxidant in plastics, has gained high concerns due to their unintended environmental release and potential threat to aquatic organisms. This study was conducted to reveal the influences of MPs on the bioaccumulation and developmental toxicity of BHA in zebrafish larvae. As a result, MPs promoted the accumulation of BHA in zebrafish larvae and enhanced the toxicity of BHA in larvae development manifested by reduced hatching rates, increased malformation rates and decreased calcified vertebrae. Although the concentration of MPs was not sufficient to cause obvious developmental toxicity, the impacts of MPs on thyroid hormones status might contribute to the aggravated join toxicity. The metabolomic mechanism was revealed to be that the coexposure of BHA and MPs affected the development of zebrafish larvae via disturbing the metabolism of arachidonic acid, glycerophospholipid, and lipids. Our results emphasized that MPs, even at the nontoxic concentrations, in combination with additives caused health risk that should not be ignored.
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