The development of an efficient pH‐universal hydrogen evolution reaction (HER) electrocatalyst is essential for practical hydrogen production. Here, an efficient and stable pH‐universal HER ...electrocatalyst composed of the strongly coupled 2D NiCo2S4 and 2D ReS2 nanosheets (NiCo2S4/ReS2) is demonstrated. The NiCo2S4/ReS2 2D–2D nanocomposite is directly grown on the surface of the carbon cloth substrate, which exhibits excellent HER performance with overpotentials of 85 and 126 mV at a current density of 10 mA cm−2 and Tafel slopes of 78.3 and 67.8 mV dec−1 under both alkaline and acidic conditions, respectively. Theoretical and experimental characterizations reveal that the chemical coupling between NiCo2S4 and ReS2 layers induces electron transfer from Ni and Co to interfacial Re‐neighbored S atoms, enabling beneficial H atom adsorption and desorption for both acidic and alkaline HER. Simultaneously, an electron transfer‐induced spin‐crossover generates high‐spin interfacial Ni and Co atoms that promote water dissociation kinetics at the NiCo2S4/ReS2 interface, which is the origin of the superior alkaline HER activity. NiCo2S4/ReS2 also shows decent catalytic activity and long‐term durability for oxygen evolution reaction, and finally bifunctionality for overall water splitting. This study suggests a rational strategy to enhance water dissociation kinetics by inducing spin‐crossover via electron transfer.
Hybrid electrochemical catalyst of NiCo2S4 nanosheets adequately covered by 2D ReS2 (NiCo2S4/ReS2) is successfully designed and exhibits excellent performance in pH‐universal hydrogen evolution and alkaline water splitting. In addition to the advantages of hierarchical structure, the result mainly comes from the electron transfer‐induced metal spin‐crossover at NiCo2S4/ReS2 interfaces simultaneously enabling beneficial H atom adsorption/desorption and accelerating water dissociation.
We decompose the energy error of any variational density functional theory calculation into a contribution due to the approximate functional and that due to the approximate density. Typically, the ...functional error dominates, but in many interesting situations the density-driven error dominates. Examples range from calculations of electron affinities to preferred geometries of ions and radicals in solution. In these abnormal cases, the error in density functional theory can be greatly reduced by using a more accurate density. A small orbital gap often indicates a substantial density-driven error.
Urea oxidation reaction (UOR) has been utilized to substitute the oxygen evolution reaction (OER), to escalate the energy conversion efficiency in electrochemical hydrogen generation processes with ...denitrification of widespread urea in wastewater. This study reports breakthroughs in Ni‐based UOR electrocatalysts, particularly with NiFe oxalate (O‐NFF), derived from Ni3Fe alloy foam with prismatic nanostructures and elevated surface area. The O‐NFF achieves cutting‐edge performances, representing 500 mA cm−2 of current density at 1.47 V RHE and exceptionally low Tafel slope of 12.1 mV dec−1 (in 1 m KOH with 0.33 m urea). X‐ray photoelectron/absorption spectroscopy (XPS/XAS) coupled with density functional theory calculations unveil that oxalate ligands induce charge deficient Ni center, promoting stable urea‐O adsorption. Furthermore, Fe dopants enhance oxalate‐O charge density and H‐bond strength, facilitating C‐N cleavage for N2 and NO2− formation. The extraordinary UOR kinetics by the tandem effects of oxalate and Fe prevent Ni over‐oxidation, corroborated by operando XAS, minimizing OER interference. It agrees with an adaptive reconstruction to Fe‐doped β‐NiOOH on top surface in extended urea electrolysis with marginal loss in UOR kinetics. This findings shed light to bimetal‐organic‐framework as (pre)catalysts to improve industrial electrolytic H2 production.
Self‐supported NiFe‐oxalate (O‐NFF) pillars show outstanding kinetics (500 mA cm−2 at 1.47 V RHE and Tafel slope of 12.1 mV dec−1) in urea oxidation reaction. In O‐NFF, Operando X‐ray absorption near edge structure confirms that the reaction with urea is dominant compared to Ni3+ being converted to Ni(3+δ)+. Density functional theory calculations highlight favorable bonding of oxalate ligand and Fe with urea‐O.
A simple, low‐cost, large area, and continuous scalable coating method is proposed for the fabrication of hybrid organic–inorganic perovskite solar cells. A megasonic spray‐coating method utilizing a ...1.7 MHz megasonic nebulizer that could fabricate reproducible large‐area planar efficient perovskite films is developed. The coating method fabricates uniform large‐area perovskite film with large‐sized grain since smaller and narrower sized mist droplets than those generated by existing ultrasonic spray methods could be generated by megasonic spraying. The volume flow rate of the CH3NH3PbI3 precursor solution and the reaction temperature are controlled, to obtain a high quality perovskite active layer. The devices reach a maximum efficiency of 16.9%, with an average efficiency of 16.4% from 21 samples. The applicability of megasonic spray coating to the fabrication of large‐area solar cells (1 cm2), with a power conversion efficiency of 14.2%, is also demonstrated. This is a record high efficiency for large‐area perovskite solar cells fabricated by continuous spray coating.
A megasonic spray‐coating system is developed for continuous fabrication of highly uniform, and large‐grain MAPbI3 films. The large‐area MAPbI3 layer (56.25 cm2) is coated via a megasonic spray‐coating system and the fabricated solar cells achieve a maximum efficiency of 16.9% with an average efficiency of 16.4% for small active area cells and 14.2% for large active area (1 cm2) cells, respectively.
Why metalloenzymes often show dramatic changes in their catalytic activity when subjected to chemically similar but non-native metal substitutions is a long-standing puzzle. Here, we report on the ...catalytic roles of metal ions in a model metalloenzyme system, human carbonic anhydrase II (CA II). Through a comparative study on the intermediate states of the zinc-bound native CA II and non-native metal-substituted CA IIs, we demonstrate that the characteristic metal ion coordination geometries (tetrahedral for Zn
, tetrahedral to octahedral conversion for Co
, octahedral for Ni
, and trigonal bipyramidal for Cu
) directly modulate the catalytic efficacy. In addition, we reveal that the metal ions have a long-range (~10 Å) electrostatic effect on restructuring water network in the active site. Our study provides evidence that the metal ions in metalloenzymes have a crucial impact on the catalytic mechanism beyond their primary chemical properties.
Highlights • We observed upregulation of SRSF 5–7 proteins in SCLC tissue for the first time. • SRSF 5–7 protein levels in SCLC were higher than in ADC or SQC types of NSCLC. • SRSFs 5–7 detected ...SCLC in the lung more efficiently than CEA or proGRP. • SRSF5 showed great diagnostic potential for SCLC and extrapulmonary cancer in PE. • SRSF5 is a novel marker for SCLC and extrapulmonary pleural metastatic cancer.
Well-defined mesoporous nanostructure electrodes have been known to have improved lithium ion reaction properties such as the lithium ion reaction, cyclability, and high rate performance. We suggest ...mesoporous tungsten nitride nanoplates prepared via a template-free synthesis for lithium-ion batteries. The as-prepared tungsten nitride (m-WN) exhibited a face-centered cubic WN phase, well-defined mesoporous structure. Furthermore, to investigate a formation mechanism of the well-defined mesoporous WN structure formed from two-dimensional WO3 nanoplates. Finally, the m-WN showed improved electrochemical reaction properties of lithium ions such as high specific capacity and high rate cycling performance due to low transport resistance and high lithium ion diffusion coefficient.
Abstract
Here,nonprecious high‐entropy chalcogenide glasses (N‐HECGs) consisting of Co, Fe, Ni, Mo, W, and Te are demonstrated in a first demonstration of acidic oxygen evolution reaction (OER). ...N‐HECGs electrocatalysts with high activity and stability are synthesized using a hierarchical hybrid approach based on a combination of electrochemical deposition and tellurization process. The as‐prepared CoFeNiMoWTe N‐HECGs electrocatalysts exhibit an amorphous, porous structure of arrayed nanosheets with abundant active sites and the increased valence states of metal cations due to the incorporated non‐metallic Te, enabling the enhancement of glass forming ability and the valence states of metal elements. Thanks to the combination of their unique geometrical and chemical structure, as well as high configuration entropy nature and high corrosion‐resistance ability, the resultant CoFeNiMoWTe N‐HECGs exhibit excellent acidic OER catalytic performance with a superior overpotential of 373 mV and outstanding stability of 100 h at the current density of 10 mA cm
−2
in 0.5
m
H
2
SO
4
. Moreover, the CoFeNiMoWTe‐based proton exchange membrane water electrolyzer is demonstrated to require a cell voltage of 1.81 V at 70 °C to obtain the practically high current density of 1 A cm
−2
, and exhibits remarkably long‐term stability for 100 h with small potential degradation of only 30 mV.
Synthesis of heterocycles from 1,2‐diarylalkene derivatives through electrosynthesis under metal‐ and oxidant‐free conditions has been discovered. Cathodic reduction of 2‐alkenylbenzoic acid or ...anodic oxidation of 2‐alkenylbenzamide, 2‐alkenylphenol and 2‐alkenylaniline leads to the formation of reactive radical intermediates which afford corresponding phthalide, isochroman‐1‐one, isoindolin‐1‐one, benzofuran, and indole in satisfying yields with good functional group tolerance. Interestingly, different chemoselectivities were found in different reaction solvents. Several mechanistic investigations including cyclic voltammetry studies and control experiments were carried out to elucidate the reaction mechanisms.
Standard density functional approximations often give questionable results for odd-electron radical complexes, with the error typically attributed to self-interaction. In density corrected density ...functional theory (DC-DFT), certain classes of density functional theory calculations are significantly improved by using densities more accurate than the self-consistent densities. We discuss how to identify such cases, and how DC-DFT applies more generally. To illustrate, we calculate potential energy surfaces of HO·Cl(-) and HO·H2O complexes using various common approximate functionals, with and without this density correction. Commonly used approximations yield wrongly shaped surfaces and/or incorrect minima when calculated self consistently, while yielding almost identical shapes and minima when density corrected. This improvement is retained even in the presence of implicit solvent.
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