The electrochemical nitrate reduction reaction (NO
RR) to ammonia is an essential step toward restoring the globally disrupted nitrogen cycle. In search of highly efficient electrocatalysts, ...tailoring catalytic sites with ligand and strain effects in random alloys is a common approach but remains limited due to the ubiquitous energy-scaling relations. With interpretable machine learning, we unravel a mechanism of breaking adsorption-energy scaling relations through the site-specific Pauli repulsion interactions of the metal d-states with adsorbate frontier orbitals. The non-scaling behavior can be realized on (100)-type sites of ordered B2 intermetallics, in which the orbital overlap between the hollow *N and subsurface metal atoms is significant while the bridge-bidentate *NO
is not directly affected. Among those intermetallics predicted, we synthesize monodisperse ordered B2 CuPd nanocubes that demonstrate high performance for NO
RR to ammonia with a Faradaic efficiency of 92.5% at -0.5 V
and a yield rate of 6.25 mol h
g
at -0.6 V
. This study provides machine-learned design rules besides the d-band center metrics, paving the path toward data-driven discovery of catalytic materials beyond linear scaling limitations.
Engineering strong metal-support interactions (SMSI) is an effective strategy for tuning structures and performances of supported metal catalysts but induces poor exposure of active sites. Here, we ...demonstrate a strong metal-support interaction via a reverse route (SMSIR) by starting from the final morphology of SMSI (fully-encapsulated core-shell structure) to obtain the intermediate state with desirable exposure of metal sites. Using core-shell nanoparticles (NPs) as a building block, the Pd-FeO
NPs are transformed into a porous yolk-shell structure along with the formation of SMSIR upon treatment under a reductive atmosphere. The final structure, denoted as Pd-Fe
O
-H, exhibits excellent catalytic performance in semi-hydrogenation of acetylene with 100% conversion and 85.1% selectivity to ethylene at 80 °C. Detailed electron microscopic and spectroscopic experiments coupled with computational modeling demonstrate that the compelling performance stems from the SMSIR, favoring the formation of surface hydrogen on Pd instead of hydride.
The ketogenic diet (KD) is a high-fat, adequate-protein, and very-low-carbohydrate diet regimen that mimics the metabolism of the fasting state to induce the production of ketone bodies. The KD has ...long been established as a remarkably successful dietary approach for the treatment of intractable epilepsy and has increasingly garnered research attention rapidly in the past decade, subject to emerging evidence of the promising therapeutic potential of the KD for various diseases, besides epilepsy, from obesity to malignancies. In this review, we summarize the experimental and/or clinical evidence of the efficacy and safety of the KD in different diseases, and discuss the possible mechanisms of action based on recent advances in understanding the influence of the KD at the cellular and molecular levels. We emphasize that the KD may function through multiple mechanisms, which remain to be further elucidated. The challenges and future directions for the clinical implementation of the KD in the treatment of a spectrum of diseases have been discussed. We suggest that, with encouraging evidence of therapeutic effects and increasing insights into the mechanisms of action, randomized controlled trials should be conducted to elucidate a foundation for the clinical use of the KD.
Fully ordered face-centered tetragonal (fct) FePt nanoparticles (NPs) are synthesized by thermal annealing of the MgO-coated dumbbell-like FePt-Fe3O4 NPs followed by acid washing to remove MgO. These ...fct-FePt NPs show strong ferromagnetism with room temperature coercivity reaching 33 kOe. They serve as a robust electrocatalyst for the oxygen reduction reaction (ORR) in 0.1 M HClO4 and hydrogen evolution reaction (HER) in 0.5 M H2SO4 with much enhanced activity (the most active fct-structured alloy NP catalyst ever reported) and stability (no obvious Fe loss and NP degradation after 20 000 cycles between 0.6 and 1.0 V (vs RHE)). Our work demonstrates a reliable approach to FePt NPs with much improved fct-ordering and catalytic efficiency for ORR and HER.
Taming interfacial electronic effects on Pt nanoparticles modulated by their concomitants has emerged as an intriguing approach to optimize Pt catalytic performance. Here, we report Pt nanoparticles ...assembled on vacancy-abundant hexagonal boron nitride nanosheets and their use as a model catalyst to embrace an interfacial electronic effect on Pt induced by the nanosheets with N-vacancies and B-vacancies for superior CO oxidation catalysis. Experimental results indicate that strong interaction exists between Pt and the vacancies. Bader charge analysis shows that with Pt on B-vacancies, the nanosheets serve as a Lewis acid to accept electrons from Pt, and on the contrary, when Pt sits on N-vacancies, the nanosheets act as a Lewis base for donating electrons to Pt. The overall-electronic effect demonstrates an electron-rich feature of Pt after assembling on hexagonal boron nitride nanosheets. Such an interfacial electronic effect makes Pt favour the adsorption of O
, alleviating CO poisoning and promoting the catalysis.
Pt alloy nanowires (NWs) were synthesized and applied as catalysts in the title reaction. The specific activity and mass activity of 2.5 nm wide FePt NWs (see TEM picture) were higher than those of a ...commercial Pt catalyst. The stability of FePt NWs was tested by scanning the potential in an O2‐saturated HClO4 solution. The corresponding polarization curves before and after the test (see picture) indicate that these NWs are robust catalysts.
We report the synthesis of core/shell face-centered tetragonal (fct)-FePd/Pd nanoparticles (NPs) via reductive annealing of core/shell Pd/Fe3O4 NPs followed by temperature-controlled Fe etching in ...acetic acid. Among three different kinds of core/shell FePd/Pd NPs studied (FePd core at ∼8 nm and Pd shell at 0.27, 0.65, or 0.81 nm), the fct-FePd/Pd-0.65 NPs are the most efficient catalyst for the oxygen reduction reaction (ORR) in 0.1 M HClO4 with Pt-like activity and durability. This enhanced ORR catalysis arises from the desired Pd lattice compression in the 0.65 nm Pd shell induced by the fct-FePd core. Our study offers a general approach to enhance Pd catalysis in acid for ORR.
Controlling nanoparticle (NP) surface strain, i.e. compression (or stretch) of surface atoms, is an important approach to tune NP surface chemistry and to optimize NP catalysis for chemical ...reactions. Here we show that surface Pt strain in the core/shell FePt/Pt NPs with Pt in three atomic layers can be rationally tuned via core structural transition from cubic solid solution denoted as face centered cubic (fcc) structure to tetragonal intermetallic denoted as face centered tetragonal (fct) structure. The high activity observed from the fct-FePt/Pt NPs for oxygen reduction reaction (ORR) is due to the release of the overcompressed Pt strain by the fct-FePt as suggested by quantum mechanics–molecular mechanics (QM–MM) simulations. The Pt strain effect on ORR can be further optimized when Fe in FePt is partially replaced by Cu. As a result, the fct-FeCuPt/Pt NPs become the most efficient catalyst for ORR and are nearly 10 times more active in specific activity than the commercial Pt catalyst. This structure-induced surface strain control opens up a new path to tune and optimize NP catalysis for ORR and many other chemical reactions.
To further enhance the catalytic activity and durability of nanocatalysts for the oxygen reduction reaction (ORR), we synthesized a new class of 20 nm × 2 nm ternary alloy FePtM (M = Cu, Ni) nanorods ...(NRs) with controlled compositions. Supported on carbon support and treated with acetic acid as well as electrochemical etching, these FePtM NRs were converted into core/shell FePtM/Pt NRs. These core/shell NRs, especially FePtCu/Pt NRs, exhibited much improved ORR activity and durability. The Fe10Pt75Cu15 NRs showed a mass current densities of 1.034 A/mgPt at 512 mV vs Ag/AgCl and 0.222 A/mgPt at 557 mV vs Ag/AgCl, which are much higher than those for a commercial Pt catalyst (0.138 and 0.035 A/mgPt, respectively). Our controlled synthesis provides a general approach to core/shell NRs with enhanced catalysis for the ORR or other chemical reactions.
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