Delicate elaboration of the nanostructures of multimetal catalytic materials with well-defined shapes and compositions to reveal their potential use as heterogeneous nanocatalysts for organic synthetic reactions with the combined merits of heterogeneous and homogeneous catalysis is both scientifically and technologically important, but this type of investigation has remained rarely pursued. In this work, we demonstrated a facile hydrothermal approach toward the one-pot shape-selective syntheses of Pd−Rh nanocrystals with tunable compositions and morphologies, including hollow nanocubes (NCs), nanoicosahedrons (NIs), and nanotruncated octahedrons (NTOs), using poly(vinylpyrrolidone) as both reductant and capping agent and halide anions (Br − /I − ) as shape control agents. The formation of Pd−Rh hollow NCs was induced by an iodine adsorbate-induced reconstruction mechanism with KI, whereas the formation of Pd−Rh NIs and NTOs were realized by controlling the selective nucleation of twinned seeds or single crystal seeds and their relative growth rates along different facets (e.g., ( 111) and (100) facets) through finely adjusting the Pd/Rh ratio and the amount of KBr added in the absence of KI. Due to the great significance of Pd-catalyzed organic reactions, the catalytic performances of Pd−Rh nanocrystals for Suzuki cross-coupling reactions with different reactants were evaluated. The measured turnover frequencies (TOFs) suggested that Pd−Rh hollow NCs held considerably enhanced catalytic activities (at least 3 times) than other Pd-based solid nanocrystals including Pd−Rh NIs, Pd−Rh NTOs, Pd−Rh NCs, Pd NCs, and commercial Pd/C, with iodobenzene as the reactant. In addition, even for more inert reactants such as bromobenzene or 4-bromotoluene, the catalytic activities of Pd−Rh hollow NCs were still impressive (showing similar TOFs to those of other shapes for reactions with iodobenzene as the reactant), indicating the promising application of Pd-based nanocatalysts for other powerful Pd-catalyzed organic synthesis reactions. Meanwhile, Pd-based solid NCs, enclosed with (100) facets only, showed better catalytic performance than NIs as well as NTOs, which had a larger fraction of (111) facets other than (100) ones, further suggesting that morphology differences were vitally significant to tune the catalytic performances of bimetallic nanocatalysts.

Multidimensional fabrication of metal-organic frameworks (MOFs) into multilevel channel integrated devices are in high demanded for Li-S separators.S uchs eparators have advantages in pore-engineering that might fulfill requirements such as intercepting the diffusing polysulfides and improving the Li + /electrolyte transfer in Li-S batteries.H owever,most reported works focus on the roles of MOFs as ionic sieves for polysulfides while offering limited investigation on the tuning of Li + transfer across the separators.Ap hotoinduced heat-assisted processing strategy is proposed to fabricate MOFs into multidimensional devices (e.g., hollow/ Janus fibers,d ouble-or triple-layer membranes). Fort he first time,at riple-layer separator with stepped-channels has been designed and demonstrated as ap owerful separator with outstanding specific capacity (1365.0 mAh g À1 )a nd cycling performance (0.03 %fading per cycle from 100 th to 700 th cycle), which is superior to single/double-layer and commercial separators.T he findings may expedite the development of MOF-based membranes and extend the scope of MOFs in energy-storage technologies.

Atomic-scale construction and high-throughput screening of robust multicomponent nanocatalysts with tunable well-defined surface structures and associated active sites for ethanol electro-oxidation reaction (EOR) in high activity and selectivity, referring to C−C bond cleavage and full oxidation of ethanol as a clean and sustainable energy source, has remained a great challenge. Herein, we demonstrate a powerful conceptual approach to design, synthesize and optimize single-crystalline Pt−Pd−Rh nanocrystals of altered shapes and compositions for enhanced EOR performance, based on combined density functional theory (DFT) calculations and experiment study. (111)-terminated Pt−Pd−Rh nano-truncated-octahedrons (NTOs) and (100)-terminated Pt−Pd−Rh nanocubes (NCs) with varied-compositions were prepared by regulating the reduction tendency of metal precursors in a facile hydrothermal method. Aided by DFT calculations, Pt3PdRh NTOs, PtPdRh NTO, and 8.8 nm PtPdRh NCs-200 were screened to be the best performing catalysts with the highest EOR activity (five times as much as that of commercial Pt black) at 0.5 V vs. NHE. Amongst these catalysts, PtPdRh NTOs exhibited the highest selectivity to CO2 at 0.5 V and the noteworthy capability to fully oxidize ethanol at extremely low potential (0.35 V); 8.8 nm PtPdRh NCs-200 possessed the best durability. Morphology and surface composition correlated to the synergistic effect of three metals were verified to affect the EOR performance of well-shaped Pt−Pd−Rh nanocrystals. Combined with in situ FTIR, it was deduced that appropriate surface composition and exposed facets were the key factors to the promoted capability in the cleavage of C−C bond down to low potential. Through adjusting surface composition and morphology of Pt−Pd−Rh nanocrystals with homogeneous element distribution, enhanced EOR performance was achieved in light of DFT simulations of the two elementary reactions (i.e., breakdown of C−C bond, and oxidation of COad). This work has offered an effective and useful strategy to promote the reactivity of multicomponent heterogeneous nanocatalysts with optimized compositions and surface structures for many industrial catalytic processes.