Nanocavity in hollow sandwiched catalysts as substrate regulator for boosting hydrodeoxygenation of biomass-derived carbonyl compounds.

Hydrodeoxygenation of oxygen-rich molecules toward hydrocarbons is attractive yet challenging in the sustainable biomass upgrading. The typical supported metal catalysts often display unstable catalytic performances owing to the migration and aggregation of metal nanoparticles (NPs) into large sizes under harsh conditions. Here, we develop a crystal growth and post-synthetic etching method to construct hollow chromium terephthalate MIL-101 (named as HoMIL-101) with one layer of sandwiched Ru NPs as robust catalysts. Impressively, HoMIL-101@Ru@MIL-101 exhibits the excellent activity and stability for hydrodeoxygenation of biomass-derived levulinic acid to gamma-valerolactone under 50°C and 1-megapascal H2, and its activity is about six times of solid sandwich counterparts, outperforming the state-of-the-art heterogeneous catalysts. Control experiments and theoretical simulation clearly indicate that the enrichment of levulinic acid and H2 by nanocavity as substrate regulator enables self-regulating the backwash of both substrates toward Ru NPs sandwiched in MIL-101 shells for promoting reaction with respect to solid counterparts, thus leading to the substantially enhanced performance.

Generalized Rapid Synthesis of Supported Nanocluster Catalyst for Mild Hydrogenation of Phenol toward KA Oil.

Homogeneous and nanometric metal clusters with unique electronic structures are promising for catalysis, however, common synthesis techniques for metal clusters suffer from large size and even metal nanocrystals attributing to their high surface energy and unsaturated configurations. Herein, a generalized rapid annealing strategy for synthesizing a series of supported metal clusters as superior catalysts is developed. Remarkably, TiO2 supported platinum nanoclusters (Pt NC/TiO2 ) exhibits the excellent catalytic activity to realize phenol hydrogenation under mild conditions. The complete phenol conversion rate and 100% selectivity toward KA oil are achieved in aqueous solution at room temperature and normal pressure. Semi-continuous scale up production of KA oil is successfully performed under mild conditions. Such excellent performance mainly originates from the partial reconstruction of Pt NC/TiO2 in aqueous phenol solution. Considering that the phenol can be produced from lignin, this study underpins a facile, sustainable, and economical route to synthesize nylon from biomass.

Recent progress on selective hydrogenation of phenol toward cyclohexanone or cyclohexanol.

Phenol is considered as an important platform molecule for synthesizing value-added chemical intermediates and products. To date, various strategies for phenol transformation have been developed, and among them, selective hydrogenation of phenol toward cyclohexanone (K), cyclohexanol (A) or the mixture KA oil has been attracted great interest because they are both the key raw materials for the synthesis of nylon 6 and 66, as well as many other chemical products, including polyamides. However, until now it is still challengeable to realize the industrilized application of phenol hydrogenation toward KA oils. To better understand the selective hydrogenation of phenol and fabricate the enabled nanocatalysts, it is necessary to summarize the recent progress on selective hydrogenation of phenol with different catalysts. In this review, we first summarize the selective hydrogenation of phenol toward cyclohexanone or cyclohexanol by different nanocatalysts, and simultaneously discuss the relationship among the active components, type of supports and their performances. Then, the possible reaction mechanism of phenol hydrogenation with the typical metal nanocatalysts is summarized. Subsequently, the possible ways for scale-up hydrogenation of phenol are discussed. Finally, the potential challenges and future developments of metal nanocatalysts for the selective hydrogenation of phenol are proposed.

Cobalt Catalysts Enable Selective Hydrogenation of CO2 toward Diverse Products: Recent Progress and Perspective.

Selective hydrogenation of carbon dioxide (CO2) into value-added chemicals has aroused great interest. The chemical inertness of CO2 and diverse reaction pathways usually require the construction of enabled catalysts. To date, cobalt (Co) catalysts characteristic of metallic and/or divalent Co components show great potential for CO2 hydrogenation. To better regulate the CO2 hydrogenation, it is necessary to summarize the current progress of cobalt catalysts for selective hydrogenation of CO2. In this Perspective, first, hydrogenation of CO2 into methane over metallic Co sites is introduced. Second, hydrogenation of CO2 into methanol and C2+ alcohols is discussed by constructing mixed-valent cobalt sites. Third, hydrogenation of CO2 into light olefins and C5+ liquid fuels over cobalt-containing hybrid catalysts is introduced. Fourth, the reaction paths for selective hydrogenation of CO2 over cobalt catalysts are illustrated. Finally, the current challenges and prospects of cobalt-based nanocatalysts for hydrogenation of CO2 are proposed.

Fe-O Clusters Anchored on Nodes of Metal-Organic Frameworks for Direct Methane Oxidation.

Direct methane oxidation into value-added organic oxygenates with high productivity under mild condition remains a great challenge. We show Fe-O clusters on nodes of metal-organic frameworks (MOFs) with tunable electronic state for direct methane oxidation into C1 organic oxygenates at 50 °C. The Fe-O clusters are grafted onto inorganic Zr6 nodes of UiO-66, while the organic terephthalic acid (H2 BDC) ligands of UiO-66 are partially substituted with monocarboxylic modulators of acetic acid (AA) or trifluoroacetic acid (TFA). Experiments and theoretical calculation disclose that the TFA group coordinated with Zr6 node of UiO-66 enhances the oxidation state of adjacent Fe-O cluster due to its electron-withdrawing ability, promotes the activation of C-H bond of methane, and increases its selective conversion, thus leading to the extraordinarily high C1 oxygenate yield of 4799 µmol gcat -1 h-1 with 97.9 % selectivity, circa 8 times higher than those modulated with AA.

Laser-Assisted Multiscale Fabrication of Configuration-Editable Supercapacitors with High Energy Density.

The construction of multidimensional, diversified microsupercapacitors (MSC) is urgently needed for fast-changing flexible and wearable microelectronics, which still meets the challenges of tedious construction and difficult integration. Herein, a laser direct writing strategy has been developed for the one-step preparation of multiscale MSCs from editable macro-supercapacitors. The microstructured supercapacitors with predefined multiscale shapes not only maintain the high capacitance performance and stability but also display the tensile properties in arbitrary direction. The heat-treated ion liquid-modified reduced graphene oxide guarantees the thermal stability of an electrode material during laser cutting, and its high ion-accessible surface area improves the capacitance performance of the supercapacitor. The as-fabricated MSC demonstrates a wide voltage window (0-3 V), high areal specific capacitance (27.4 mF cm-2), and high energy density (32.1 µW h cm-2), which are far higher than those of most reported articles. Notably, the editable supercapacitors can imitate the stereo paper cutting to achieve an arbitrary one-dimensional to three-dimensional configuration, promising for various portable, stretchable, and wearable devices.

Laser-Assisted Large-Scale Fabrication of All-Solid-State Asymmetrical Micro-Supercapacitor Array.

The micro-supercapacitors are of great value for portable, flexible, and integrated electronic equipments. Here, the large-scale and integrated asymmetrical micro-supercapacitor (AMSC) array is fabricated in virtue of the laser direct writing and electrodeposition technology. The AMSC shows the ideal flexibility, high areal specific capacitance (21.8 mF cm-2 ), and good rate capability. Moreover, its energy density reaches 12.16 µW h cm-2 , outperforming most micro-supercapacitors reported previously. Meanwhile, large-scale series-connected AMSCs are integrated on the flexible substrates (e.g., indium tin oxide-polyethylene terephthalate film), which can power a veriety of the commercial electronics. The combination of AMSCs array, solar cell, and electronic device proves the feasibility for practical application in the portable, flexible, and integrated electronic equipments.