P2‐Na0.67AlxMn1−xO2: Cost‐Effective,Stable and High‐Rate Sodium Electrodes by Suppressing Phase Transitions and Enhancing Sodium Cation Mobility

Sodium layered P2‐stacking Na_0.67MnO₂ materials have shown great promise for sodium‐ion batteries. However, the undesired Jahn–Teller effect of the Mn⁴⁺/Mn³⁺ redox couple and multiple biphasic structural transitions during charge/discharge of the materials lead to anisotropic structure expansion and rapid capacity decay. Herein, by introducing abundant Al into the transition‐metal layers to decrease the number of Mn³⁺, we obtain the low cost pure P2‐type Na_0.67Al_xMn_1?xO₂ (x=0.05, 0.1 and 0.2) materials with high structural stability and promising performance. The Al‐doping effect on the long/short range structural evolutions and electrochemical performances is further investigated by combining in situ synchrotron XRD and solid‐state NMR techniques. Our results reveal that Al‐doping alleviates the phase transformations thus giving rise to better cycling life, and leads to a larger spacing of Na⁺ layer thus producing a remarkable rate capability of 96 mAh g^‐1 at 1200 mA g^‐1.     

Engineering of Ruthenium–Iron Oxide Colloidal Heterostructures: Improved Yields in CO2 Hydrogenation to Hydrocarbons

Catalytic CO₂ reduction to fuels and chemicals is a major pursuit in reducing greenhouse gas emissions. One approach utilizes the reverse water‐gas shift reaction, followed by Fischer–Tropsch synthesis, and iron is a well‐known candidate for this process. Some attempts have been made to modify and improve its reactivity, but resulted in limited success. Now, using ruthenium–iron oxide colloidal heterodimers, close contact between the two phases promotes the reduction of iron oxide via a proximal hydrogen spillover effect, leading to the formation of ruthenium–iron core–shell structures active for the reaction at significantly lower temperatures than in bare iron catalysts. Furthermore, by engineering the iron oxide shell thickness, a fourfold increase in hydrocarbon yield is achieved compared to the heterodimers. This work shows how rational design of colloidal heterostructures can result in materials with significantly improved catalytic performance in CO₂ conversion processes.     

DNP‐Supported Solid‐State NMR Spectroscopy of Proteins Inside Mammalian Cells

Elucidating at atomic level how proteins interact and are chemically modified in cells represents a leading frontier in structural biology. We have developed a tailored solid‐state NMR spectroscopic approach that allows studying protein structure inside human cells at atomic level under high‐sensitivity dynamic nuclear polarization (DNP) conditions. We demonstrate the method using ubiquitin (Ub), which is critically involved in cellular functioning. Our results pave the way for structural studies of larger proteins or protein complexes inside human cells, which have remained elusive to in‐cell solution‐state NMR spectroscopy due to molecular size limitations.     

Strong Metal–Support Interactions between Copper and Iron Oxide during the High‐Temperature Water‐Gas Shift Reaction

The commercial high‐temperature water‐gas shift (HT‐WGS) catalyst consists of CuO‐Cr₂O₃‐Fe₂O₃, where Cu functions as a chemical promoter to increase the catalytic activity, but its promotion mechanism is poorly understood. In this work, a series of iron‐based model catalysts were investigated with in situ or pseudo in situ characterization, steady‐state WGS reaction, and density function theory (DFT) calculations. For the first time, a strong metal‐support interaction (SMSI) between Cu and FeO_x was directly observed. During the WGS reaction, a thin FeO_x overlayer migrates onto the metallic Cu particles, creating a hybrid surface structure with Cu‐FeO_x interfaces. The synergistic interaction between Cu and FeO_x not only stabilizes the Cu clusters, but also provides new catalytic active sites that facilitate CO adsorption, H₂O dissociation, and WGS reaction. These new fundamental insights can potentially guide the rational design of improved iron‐based HT‐WGS catalysts.     

Knight Shift in 13C NMR Resonances Confirms the Coordination of N‐Heterocyclic Carbene Ligands to Water‐Soluble Palladium Nanoparticles

The coordination of N‐heterocyclic carbene (NHC) ligands to the surface of 3.7 nm palladium nanoparticles (PdNPs) can be unambiguously established by observation of Knight shift (KS) in the ¹³C resonance of the carbenic carbon. In order to validate this coordination, PdNPs with sizes ranging from 1.3 to 4.8 nm were prepared by thermal decomposition or reduction with CO of a dimethyl NHC Pd^II complex. NMR studies after ¹³CO adsorption established that the KS shifts the ¹³C resonances of the chemisorbed molecules several hundreds of ppm to high frequencies only when the particle exceeds a critical size of around 2 nm. Finally, the resonance of a carbenic carbon is reported to be Knight‐shifted to 600 ppm for ¹³C‐labelled NHCs bound to PdNPs of 3.7 nm. The observation of these very broad KS resonances was facilitated by using Car–Purcell–Meiboom–Gill (CPMG) echo train acquisition NMR experiments.     

探究Cu/ZnO相互作用对CO2加氢制甲醇反应性能的影响

Using renewable green hydrogen and carbon dioxide (CO₂) to produce methanol is one of the fundamental ways to reduce CO₂ emissions in the future, and research and development related to catalysts for efficient and stable methanol synthesis is one of the key factors in determining the entire synthesis process. Metal nanoparticles stabilized on a support are frequently employed to catalyze the methanol synthesis reaction. Metal-support interactions (MSIs) in these supported catalysts can play a significant role in catalysis. Tuning the MSI is an effective strategy to modulate the activity, selectivity, and stability of heterogeneous catalysts. Numerous studies have been conducted on this topic; however, a systematic understanding of the role of various strengths of MSI is lacking. Herein, three Cu/ZnO-SiO₂ catalysts with different strengths of MSI, namely, normal precipitation Cu/ZnO-SiO₂ (Nor-CZS), co-precipitation Cu/ZnO-SiO₂ (Co-CZS), and reverse precipitation Cu/ZnO-SiO₂ (Re-CZS), were successfully prepared to determine the role of such interactions in the hydrogenation of CO₂ to methanol. The results of temperature-programmed reduction (H₂-TPR) and X-ray photoelectron spectroscopy (XPS) characterization illustrated that the MSI of the catalysts was considerably affected by the precipitation sequence. Fourier transform infrared reflection spectroscopy (FT-IR) results indicated that the Cu species existed as CuO in all cases and that copper phyllosilicate was absent (except for strong Cu-SiO₂ interaction). Transmission electron microscopy (TEM), X-ray diffraction (XRD), and N₂O chemical titration results revealed that strong interactions between the Cu and Zn species would promote the dispersion of Cu species, thereby leading to a higher CO₂ conversion rate and improved catalytic stability. As expected, the Re-CZS catalyst exhibited the highest activity with 12.4% CO₂ conversion, followed by the Co-CZS catalyst (12.1%), and the Nor-CZS catalyst (9.8%). After the same reaction time, the normalized CO₂ conversion of the three catalysts decreased in the following order: Re-CZS (75%) > Co-CZS (70%) > Nor-CZS (65%). Notably, the methanol selectivity of the Re-CZS catalyst was found to level off after a prolonged period, in contrast to that of Co-CZS and Nor-CZS. Investigation of the structural evolution of the catalyst with time on stream revealed that the high methanol selectivity of the catalyst was caused by the reconstruction of the catalyst, which was induced by the strong MSI between the Cu and Zn species, and the migration of ZnO onto Cu species, which caused an enlargement of the Cu/ZnO interface. This work offers an alternative strategy for the rational and optimized design of efficient catalysts.     

Hydrogenation of CO2‐Derived Carbonates and Polycarbonates to Methanol and Diols by Metal–Ligand Cooperative Manganese Catalysis

The first base‐metal‐catalysed hydrogenation of CO₂‐derived carbonates to alcohols is presented. The reaction proceeds under mild conditions in the presence of a well‐defined manganese complex with a loading as low as 0.25 mol %. The non‐precious‐metal homogenous catalytic system provides an indirect route for the conversion of CO₂ into methanol with the co‐production of value‐added (vicinal) diols in yields of up to 99 %. Experimental and computational studies indicate a metal–ligand cooperative catalysis mechanism.