Tuning the surface strain of heterogeneous catalysts represents a powerful strategy to engineer their catalytic properties by altering the electronic structures. However, a clear and systematic understanding of strain effect in electrochemical reduction of carbon dioxide is still lacking, which restricts the use of surface strain as a tool to optimize the performance of electrocatalysts. Herein, we demonstrate the strain effect in electrochemical reduction of CO by using Pd octahedra and icosahedra with similar sizes as a well-defined platform. The Pd icosahedra/C catalyst shows a maximum Faradaic efficiency for CO production of 91.1 % at -0.8 V versus reversible hydrogen electrode (vs. RHE), 1.7-fold higher than the maximum Faradaic efficiency of Pd octahedra/C catalyst at -0.7 V (vs. RHE). The combination of molecular dynamic simulations and density functional theory calculations reveals that the tensile strain on the surface of icosahedra boosts the catalytic activity by shifting up the d-band center and thus strengthening the adsorption of key intermediate COOH*. This strain effect was further verified directly by the surface valence-band photoemission spectra and electrochemical analysis.

For the first time, we report herein bottom-up fabrication of a conductive nickel phthalocyanine-based 2D MOF and use it as a highly active electrocatalyst for OER (overpotential < 250 mV) without further pyrolysis or adding conductive materials, which can facilitate the development of 2D MOFs for energy applications.

Highlights d High-alcohol-producing strains of Klebsiella pneumoniae exist in humans d HiAlc Kpn is associated with NAFLD in a human cohort d Transplant of HiAlc Kpn into mice causes NAFLD d Feeding mice glucose led to detectable blood alcohol, suggesting a biomarker for NAFLD

In the originally published version of this article, the ultra-high blood alcohol concentration was mistakenly given as 400 mg/L instead of 400 mg/dL. The correction has now been made online. This error does not affect the conclusions of the paper. The authors apologize for any confusion that this error may have caused.

All-inorganic cesium lead halide perovskite nanocrystals have emerged as attractive optoelectronic nanomaterials owing to their stabilities and highly efficient photoluminescence. However, the inorganic perovskites of CsPbBr3 synthesized by the solution method often suffer from byproducts such as Cs4PbBr6 and CsPb2Br5. Herein, we have investigated thoroughly the solvent-related effect on the phase formation in CsBr–PbBr2 system through single crystal X-ray diffraction measurement. It is found that the prepared product is dominantly determined by the coordination number (CN) of Pb­(II) and the ratio of precursors. By use of dimethyl sulfoxide (DMSO) or dimethylformamide (DMF) as the solvent, Pb2+ is found to be surrounded by six-coordination sites, and the products can be tuned from CsPbBr3 to Cs4PbBr6 by increasing the precursor ratio of CsBr to PbBr2. On the contrary, in the solvent of water, only Pb2+ eight-coordinated crystal of CsPb2Br5 can be produced, regardless of the ratio of CsBr to PbBr2. More importantly, with the investigation of the extended X-ray absorption fine structure (EXAFS) for Pb L-II edge in precursor solutions, we identify that the CNs of Pb­(II) of resultants are the same as those of the corresponding plumbite oligomers in precursor solutions. In addition, the phase transitions from Cs4PbBr6 to CsPbBr3, amorphous state, and CsPb2Br5 triggered by water vapor have also been observed clearly. This work not only enriches our understanding of the phase formation of CsBr–PbBr2 system but also provides the knowledge of the degradation of halide perovskites in the environment of humidity.

Instability of emerging perovskite organometallic halide in humidity environment is the biggest obstacle for its potential applications in solar energy harvest and electroluminescent display. Understanding the detailed decay mechanism of these materials in moisture is a critical step towards the final appropriate solutions. As a model study presented in this work, in situ synchrotron radiation x-ray diffraction was combined with microscopy and gravimetric analysis to study the degradation process of CH3NH3PbI3 in moisture, and the results reveal that: 1) intermediate monohydrated CH3NH3PbI3·H2O is detected in the degradation process of CH3NH3PbI3 and the final decomposition products are PbI2 and aqueous CH3NH3I; 2) the aqueous CH3NH3I could hardly further decompose into volatile CH3NH2, HI or I2; 3) the moisture disintegrate CH3NH3PbI3 and then alter the distribution of the decomposition products, which leads to an incompletely-reversible reaction of CH3NH3PbI3 hydrolysis and degrades the photoelectric properties. These findings further elucidate the picture of hydrolysis process of perovskite organometallic halide in humidity environment.

Tuning the surface strain of heterogeneous catalysts represents ap owerful strategy to engineer their catalytic properties by altering the electronic structures.H owever, ac lear and systematic understanding of strain effect in electrochemical reduction of carbon dioxide is still lacking, which restricts the use of surface strain as atool to optimize the performance of electrocatalysts.H erein, we demonstrate the strain effect in electrochemical reduction of CO 2 by using Pd octahedra and icosahedra with similar sizes as aw ell-defined platform. The Pd icosahedra/C catalyst shows am aximum Faradaic efficiency for CO production of 91.1 %a tÀ0.8 V versus reversible hydrogen electrode (vs.RHE), 1.7-fold higher than the maximum Faradaic efficiency of Pd octahedra/C catalyst at À0.7 V( vs.R HE). The combination of molecular dynamic simulations and density functional theory calculations reveals that the tensile strain on the surface of icosahedra boosts the catalytic activity by shifting up the d-band center and thus strengthening the adsorption of key intermediate COOH*. This strain effect was further verified directly by the surface valence-band photoemission spectra and electrochemical analysis.

Mechanism of metal-insulator transition (MIT) in strained VO2 thin films is very complicated and incompletely understood despite three scenarios with potential explanations including electronic correlation (Mott mechanism), structural transformation (Peierls theory) and collaborative Mott-Peierls transition. Herein, we have decoupled coactions of structural and electronic phase transitions across the MIT by implementing epitaxial strain on 13-nm-thick (001)-VO2 films in comparison to thicker films. The structural evolution during MIT characterized by temperature-dependent synchrotron radiation high-resolution X-ray diffraction reciprocal space mapping and Raman spectroscopy suggested that the structural phase transition in the temperature range of vicinity of the MIT is suppressed by epitaxial strain. Furthermore, temperature-dependent Ultraviolet Photoelectron Spectroscopy (UPS) revealed the changes in electron occupancy near the Fermi energy EF of V 3d orbital, implying that the electronic transition triggers the MIT in the strained films. Thus the MIT in the bi-axially strained VO2 thin films should be only driven by electronic transition without assistance of structural phase transition. Density functional theoretical calculations further confirmed that the tetragonal phase across the MIT can be both in insulating and metallic states in the strained (001)-VO2/TiO2 thin films. This work offers a better understanding of the mechanism of MIT in the strained VO2 films.