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•Strong metal–support interaction (SMSI) is observed within monodisperse nanoparticles.•These monodisperse nanoparticles consist of PdGa alloy and Ga2O3.•The typical composite ...structure of nanoparticles leads to SMSI.•PdGa nanoparticles can be used as self-support catalysts for semi-hydrogenation.
The strong metal–support interaction (SMSI) between metals and reducible supports (e.g., CeO2, TiO2, and SnO2), which has been widely investigated, plays a very important role in heterogeneous catalysis. We report the first example of SMSI between palladium (Pd) and gallium oxide (Ga2O3) within a PdGa nanoparticle (denoted as PdxGay NP, where x:y is the atomic ratio of Pd and Ga). The typical features of classic SMSI, such as electron transfer between Ga2O3 and Pd and suppression of H2 and CO adsorption, are successfully observed on PdxGay NPs. Detailed characterizations and control experiments demonstrate that the coexistence of PdGa alloy and Ga2O3 in PdxGay NPs plays a vital role in the formation of SMSI. To systematically study the effects of SMSI on catalytic performance, PdxGay NPs were used as “self-supported catalysts” for propyne semi-hydrogenation (PSH), a critical process for removing trace propyne from propylene in industry. It is shown that optimized Pd0.34Ga1 NPs give a propylene selectivity of 98.2% at a propyne conversion of 96.6% at 30 °C and atmospheric pressure, which is much higher than that of pure Pd NPs and Pd/Ga2O3 catalysts prepared by a conventional wet-impregnation method. The reaction paths of PSH on PdxGay NPs have been further revealed by density functional theory (DFT) calculations. This work may not only deepen the basic understanding of SMSI, but also promote the design and application of heterogeneous catalysts.
Developing efficient Pt-based electrocatalysts for the methanol oxidation reaction (MOR) is of pivotal importance for large-scale application of direct methanol fuel cells (DMFCs), but Pt suffers ...from severe deactivation brought by the carbonaceous intermediates such as CO. Here, we demonstrate the formation of a bismuth oxyhydroxide (BiO x (OH) y )-Pt inverse interface via electrochemical reconstruction for enhanced methanol oxidation. By combining density functional theory calculations, X-ray absorption spectroscopy, ambient pressure X-ray photoelectron spectroscopy, and electrochemical characterizations, we reveal that the BiO x (OH) y -Pt inverse interface can induce the electron deficiency of neighboring Pt; this would result in weakened CO adsorption and strengthened OH adsorption, thereby facilitating the removal of the poisonous intermediates and ensuring the high activity and good stability of Pt2Bi sample. This work provides a comprehensive understanding of the inverse interface structure and deep insight into the active sites for MOR, offering great opportunities for rational fabrication of efficient electrocatalysts for DMFCs.
Building a reliable relationship between the electronic structure of alloyed metallic catalysts and catalytic performance is important but remains challenging due to the interference from many ...entangled factors. Herein, a PdBi surface alloy structural model, by tuning the deposition rate of Bi atoms relative to the atomic interdiffusion rate at the interface, realizes a continuous modulation of the electronic structure of Pd. Using advanced X-ray characterization techniques, we provide a precise depiction of the electronic structure of the PdBi surface alloy. As a result, the PdBi catalysts show enhanced propene selectivity compared with the pure Pd catalyst in the selective hydrogenation of propyne. The prevented formation of saturated β-hydrides in the subsurface layers and weakened propene adsorption on the surface contribute to the high selectivity. Our work provides in-depth understanding of the electronic properties of surface alloy structure and underlies the study of the electronic structure–performance relationship in bimetallic catalysts.
Butadiene (BD) is a critical raw material in chemical industry, which is conventionally produced from naphtha cracking. The fast‐growing demand of BD and the limited oil reserve motivate chemists to ...develop alternative methods for BD production. Shale gas, which mainly consists of light alkanes, has been considered as cheap raw materials to replace oil for BD production via n‐butane direct dehydrogenation (n‐BDH). However, the quest for highly‐efficient catalysts for n‐BDH is driven by the current drawback of low BD selectivity. Here, we demonstrate a strategy for boosting the selectivity of BD by suppressing dehydroisomerization, an inevitable step in the conventional n‐BDH process which largely reduces the selectivity of BD. Detailed investigations show that the addition of alkali‐earth metals (e. g., Mg and Ca) into Pt‐Ga2O3/S10 catalysts increases Pt dispersity, suppresses coke deposition and dehydroisomerization, and thus leads to the significant increase of BD selectivity. The optimized catalyst displays an initial BD selectivity of 34.7 % at a n‐butane conversion of 82.1 % at 625 °C, which outperforms the reported catalysts in literatures. This work not only provides efficient catalysts for BD production via n‐BDH, but also promotes the researches on catalyst design in heterogeneous catalysis.
The addition of alkaline‐earth metals into Pt‐Ga2O3 catalyst can significantly suppress the dehydroisomerization and coke deposition during n‐butane dehydrogenation, increase the Pt dispersity and stabilize Pt atoms at high temperature. Consequently, the optimal catalyst of 0.1Pt6Mg2Ga/S10 displays a n‐butane conversion of 82.1 % at a butadiene selectivity of 34.7 % at 625 °C, which has outperformed the reported catalysts for n‐butane dehydrogenation.
Driving metal-cluster-catalyzed high-temperature chemical reactions by sunlight holds promise for the development of negative-carbon-footprint industrial catalysis, which has yet often been hindered ...by the poor ability of metal clusters to harvest and utilize the full spectrum of solar energy. Here, we report the preparation of Mo2TiC2 MXene-supported Ru clusters (Ru/Mo2TiC2) with pronounced broadband sunlight absorption ability and high sintering resistance. Under illumination of focused sunlight, Ru/Mo2TiC2 can catalyze the reverse water–gas shift (RWGS) reaction to produce carbon monoxide from the greenhouse gas carbon dioxide and renewable hydrogen with enhanced activity, selectivity, and stability compared to their nanoparticle counterparts. Notably, the CO production rate of MXene-supported Ru clusters reached 4.0 mol·gRu –1·h–1, which is among the best reported so far for photothermal RWGS catalysts. Detailed studies suggest that the production of methane is kinetically inhibited by the rapid desorption of CO from the surface of the Ru clusters.
Auto‐programmable shape memory polymers (AP‐SMPs) can deform automatically without external manipulation, exhibiting either a free‐standing temporary shape or a permanent shape. The unique shape ...memory behaviors derive mainly from control by two factors, water and temperature. However, the control mechanism is unknown. This study analyzes and demonstrates the dual‐control mechanism of water and temperature in the three shape‐changing processes of AP‐SMPs. First, the AP‐SMP is immersed in warm water (50 °C). Asymmetric swelling of bilayer films provides the driving force for the shape auto‐programming of the AP‐SMP. The solvent effect of water reduces the glass transition temperature (Tg) of the AP‐SMP, which becomes lower than the medium temperature in warm water. AP‐SMP can be programmed automatically. Then, the AP‐SMP is removed from water and placed in air at room temperature. The Tg value of the matrix film increases notably in air and exceeds the medium temperature. The temporary shape of the AP‐SMP can thus be fixed. Finally, the AP‐SMP can quickly return to its permanent shape when the medium temperature exceeds the matrix film Tg in air. The dual control shape memory mechanism provides insights into the design and development of AP‐SMPs.
The dual‐control mechanism of water and temperature in automatically programmable shape memory polymers (AP‐SMPs) is studied. Water provides a driving force and controls the Tg value of the matrix film. Temperature controls the relationship between the medium temperature and matrix film Tg.
Hydro-depolymerization presents a promising avenue for transforming plastic waste into high-value hydrocarbons, offering significant potential for value-added recycling. However, a major challenge in ...this method arises from kinetic limitations due to insufficient hydrogen concentration near the active sites, requiring optimal catalytic performance only at higher hydrogen pressures. In this study, we address this hurdle by developing “hydrogen bubble catalysts” featuring Ru nanoparticles within mesoporous SBA-15 channels (Ru/SBA). The distinctive feature of Ru/SBA catalysts lies in their capacity for physical hydrogen storage and chemically reversible hydrogen spillover, ensuring a timely and ample hydrogen supply. Under identical reaction conditions, the catalytic activity of Ru/SBA surpassed that of Ru/SiO2 (no hydrogen storage capacity) by over 4-fold. This substantial enhancement in catalytic performance provides significant opportunities for near atmospheric pressure hydro-depolymerization of plastic waste.
Even though extensive efforts have been devoted to mixing Pd nanocrystals with Ni(OH)2 for the enhanced synergy, it remains a great challenge to incorporate nanosized Ni(OH)2 species on the Pd ...electrode and reveal their synergy. Herein, we present spongelike Pd nanocrystals with the modification of amorphous Ni(OH)2 species. The catalyst configuration is first considered by compositing Pd with Ni(OH)2 species to optimize the Pd–Pd interatomic distance and then constructing a strongly coupled interface between Pd nanostructures and Ni(OH)2 species. For the ethanol oxidation reaction (EOR) and the formic acid oxidation reaction (FAOR), Pd-Ni(OH)2 composites exhibit an impressive mass activity of 4.98 and 2.65 A mgPd –1, respectively. Most impressively, there is no significant decrease in the EOR activity during five consecutive cycles (50 000 s). A series of CO-poisoning tests have proved that the enhanced EOR and FAOR performances involve synergy between Pd nanostructures and Ni(OH)2 species.
Two-dimensional (2D) metal carbides, carbonitrides, and nitrides (MXenes) have recently emerged as promising candidates in catalysis due to their unique properties. In this work, we composited Ti3C2 ...with Co-embedded N-doped carbon nanotubes (CNTs) via the pyrolysis of zeolitic imidazolate frameworks (ZIF-67) for propyne selective hydrogenation. Detailed characterizations show that strong synergistic effects are observed between the Ti3C2 and Co-embedded N-doped CNTs in the composite catalysts. This work provides an efficient strategy to achieve N-doping on Co nanoparticles, which play a vital role in the propyne selective hydrogenation. The optimized catalyst gives a high propyne conversion (∼99%) and high propene selectivity (∼96%) on propyne selective hydrogenation at 150 °C, which surpasses the reported non-noble metal catalysts in literature works. This work may not only open an avenue for obtaining active and selective catalysts for propyne selective hydrogenation but also promote research on the role of MXenes in catalysis.
