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Hydrazine hydrate as a hydrogen source has a good effect on nitro reduction, but overuse has environmental toxicity and is prone to over‐hydrogenation, resulting in low selectivity. Herein, we report a magnetically separable Rh/Fe3O4 (1.26 wt%) catalyst containing an optimal Rh content that can completely convert 3‐nitrostyrene to 3‐vinylaniline (> 99% selectivity) using a stoichiometric molar ratio of hydrazine hydrate (‐NO2:N2H4·H2O = 1:1.5). This is due to the synergy between Rh and Fe3O4 and the natural selectivity of N2H4·H2O for nitro. The synergy can reduce the activation energy of the reaction (36.6 kJ/mol), increasing the reduction rate of nitro group and avoiding the combination of active hydrogen species (H*) to H2 as well as the hydrogenation of N2H4 to NH3. Moreover, the active H* produced by N2H4·H2O is different from that produced by H2, and excess dose of N2H4 will inevitably yield H2 thus decline the selectivity. [ABSTRACT FROM AUTHOR]

Nanocatalysts are likely to contain undetected single-atom components, which may have been ignored but have significant effect in catalytic reactions. Herein, we report a catalyst composed of Mo single atoms (SAs) and MoO2 nanoparticles (NPs) (MoSAs-MoO2@NC), which is an exact model to understand how the SAs contribute to the nanocatalyst. Both experimental results and the density functional theory calculations reveal that Mo SAs on nitrogen-doped carbon provides the reaction zone for nitro reduction, while MoO2 is the active site for decomposing hydrazine hydrate to produce H⋆. Thanks to the synergy between Mo SAs and MoO2 NPs, this catalyst exhibits noble metal-like catalytic activity (100% conversion at 4 min) for the dechlorination-proof transfer hydrogenation. Additionally, the hydrogen migration on the catalyst is verified by the electrochemical tests in the absence of a hydrogen source. This work provides a model for further study on the coexistence of single atoms in nanoparticle catalysts. [ABSTRACT FROM AUTHOR]

Surface wettability of heterogeneous catalysts plays a crucial role in the catalytic activity and selectivity. In this work, an ultra‐thin modified silica coating is firstly used as the "skin" to adjust the surface hydrophilicity of the catalyst, which promotes the catalytic activity and selectivity in the transfer hydrogenation of nitriles. The ultrathin‐modified silica "skin" with 2–3 nm thickness is fabricated by the consecutive hydrolysis of (3‐aminopropyl)triethoxysilane and n‐propyltriethoxysilane, and the bimetallic catalyst Fe3O4@PtCu is encapsulated in the coating. The modified catalyst demonstrated significant catalytic efficiency for hydrogenation of benzonitrile to dibenzylamine. The reaction performs 93% conversion and 99% selectivity in "green" solvent H2O. Furthermore, the modified silica "skin" encapsulates the PtCu nanoparticles to prevent the leaching of active sites, thus brings excellent catalytic recyclability. More than Fe3O4@PtCu, the modified silica "skin" is applicable to a diverse range of catalysts, that is, PtCu/SiO2, PtCu/Al2O3, and PtCu/UiO‐66, endowing them with additional catalytic activity and selectivity in the hydrogenation of nitriles. [ABSTRACT FROM AUTHOR]

A novel armor‐type composite of metal–organic framework (MOF)‐encapsulated CoCu nanoparticles with a Fe3O4 core (Fe3O4@SiO2‐NH2‐CoCu@UiO‐66) has been designed and synthesized by the half‐way injection method, which successfully serves as an efficient and recyclable catalyst for the selective transfer hydrogenation. In this half‐way injection approach, the pre‐synthetic Fe3O4@SiO2‐NH2‐CoCu was injected into the UiO‐66 precursor solution halfway through the MOF budding period. The formed MOF armor could play a role of providing significant additional catalytic sites besides CoCu nanoparticles, protecting CoCu nanoparticles, and improving the catalyst stability, thus facilitating the selective transfer hydrogenation of nitrobenzaldehydes into corresponding nitrobenzyl alcohols in high selectivity (99 %) and conversion (99 %) rather than nitro group reduction products. Notably, this method achieves the precise assembly of a MOF‐encapsulated composite, and the ingenious combination of MOF and nanoparticles exhibits excellent catalytic performance in the selective hydrogen transfer reaction, implementing a "1+1>2" strategy in catalysis. [ABSTRACT FROM AUTHOR]

Developing efficient, sustainable, and stable nanocatalysts continue being the struggling goal both for academia and for industrial. Carbocatalysts have attracted great attention due to high mass transfer ability, environmental sustainability and stability. Fabricating well‐defined carbonaceous nanocatalysts for heterogeneous catalysis is intensively pursuing. In this work, a newly developed economic and facile method was applied for the large‐scale fabrication of graphite sheet encapsulated magnetic carbocatalysts. The carbocatalysts was constructed via in‐situ pyrolysis of melamine‐metallo‐supramolecular polymer precursors (MMSP) under vacuum condition. The framework of MMSP was synthesized through the condensation reaction. As a proof‐of‐concept, this method was successfully applied for the fabrication of three kinds of graphite encapsulated magnetic carbocatalysts. Based on systematically optimization, the Pt−NiO‐1000@NC‐650 nanocatalyst demonstrated highly efficient and remarkable stability for the catalytic transfer hydrogenation of 4‐nitrophenol to produce corresponding 4‐aminophenol. The kinetics study of this catalytic system illustrates the reaction order is 1st for Pt−NiO‐1000@NC‐650. Furthermore, the kinetic constant (Kapp) is 1.57 min−1 and the turnover frequency (TOF) is up to 4, 268 h−1. [ABSTRACT FROM AUTHOR]

As a typical 3d transition metal, Cu exhibits competitive potential in the catalytic transfer hydrogenation of nitriles due to its low price and appropriate catalytic activity. Unfortunately, the Cu-based catalyst usually requires additional metals to realize good catalytic activity, this makes it difficult to understand the role of Cu. Herein, an amino-modified hollow mesoporous double-shell SiO 2 @C (AmHMSiO 2 @C) microsphere was applied as a nanoreactor, which achieves the high selective hydrogenation of nitriles over the Cu-only catalyst. The conversion and selectivity to primary amines were 100% and 96% respectively at 60 °C using amino borane as the hydrogen source, and the TOF reaches 199.75 h−1 for Cu. The unique structure of the Cu@AmHMSiO 2 @C enhances the activity and stability of the Cu active sites. Comparative experiments demonstrate that the synergy between the nanoreactor and Cu nanoparticles enables the desirable catalytic performance toward the hydrogenation of nitriles to primary amines under mild reaction conditions. This work offers a distinct case for constructing an efficient Cu-based catalyst for heterogeneous hydrogenation reactions. [Display omitted] • Cu@AmHMSiO 2 @C exhibits desirable catalytic performance for the hydrogenation of nitriles to primary amines. • The Cu@AmHMSiO 2 @C nanoreactor exhibited excellent TOF values of 199.75 h−1. • Cu metal, the void-confinement effect, and modified mesoporous SiO 2 @C double-shell are indispensable in this nanoreactor. [ABSTRACT FROM AUTHOR]

The recycle and reutilization of antimony in industrial sewage is an important issue. Here, we developed a protocol for the efficient antimony adsorption and the resourcization of the waste adsorbent. Following the concept of "treat waste by waste", the adsorbent was produced with a kind of waste, pomelo peel, which was transferred to the biochar loaded ferric oxide (Fe 3 O 4 /BC) as the adsorbent. The Fe 3 O 4 /BC exhibited a fast procedure for the adsorption of antimony, and its maximum Sb(III) adsorption capacity reached 246.19 mg g−1 at 40 °C. Next, the re-utilization of the waste adsorbents was considered to avoid the secondary pollution of the solid waste. Taking the treatment of textile printing waste water as a real application, we realized the stepwise resourcization of the waste adsorbents as catalysts. The used adsorbents, Sb(III)/Fe 3 O 4 /BC, were extracted by KOH glycol solution and the eluent was directly used in synthesizing polyethylene terephthalate (PET). The remained part of the adsorbents could be converted into the catalyst for transfer hydrogenation (CTH) of nitroarenes. This work helps to achieve the waste-free application of antimony, and delivers an overall solution of Sb-containing waste water, which follows the concept of "turning waste into treasure". [Display omitted] • We developed a biochar loaded ferric oxide (Fe3O4/BC) as the adsorbent. • The maximum adsorption capacity of the adsorbent for Sb(III) was 246.19 mg/g. • The eluent could be directly used in the synthesis of polyethylene terephthalate. • The used adsorbents could be converted into a catalyst for reduction of nitroarenes. [ABSTRACT FROM AUTHOR]

Chemoselective hydrogenation of nitrostyrene to aminostyrene still faces the trouble of low selectivity and poor activity. The bimetallic catalysts, which adjust the activity of noble metal nanoparticles through the doping of non-noble metals, are promising for selectively catalytic transfer hydrogenation (CTH). For another aspect, the hydrogen source also plays a vital role in selective CTH. Based on this, we prepared activity-inhibited bimetallic RhIn/ZIF-8 catalyst to study the catalytic performance towards different hydrogen sources (N 2 H 4 ·H 2 O, NaBH 4 , NH 3 ·BH 3 and H 2) and to explore the natural selectivity of these hydrogen sources. We found that the hydrazine hydrate was the most selective H-donor for the nitro group, while the H 2 had the highest natural selectivity to olefins. The H 2 produced from hydrazine hydrate is responsible for the formation of completely reduced products. The potential reduction by the intermediate imine did not occur to C C double bonds, this indicates controlling the decomposition of N 2 H 4 will enhance the selectivity of nitroarenes. Based on this, the reaction system with the catalyst bimetallic RhIn/ZIF-8 and N 2 H 4 ·H 2 O as the hydrogen source is established, which can fully reduce many nitrostyrenes with >98% selectivity to corresponding aminostyrenes. [Display omitted] • Exploring the intrinsic selectivity of different hydrogen sources. • The reduction of the nitro group by the imine intermediate is excluded. • Inhibiting the decomposition of hydrazine hydrate is a key factor to ensure the selectivity of this card. • Developing a catalytic reaction system with selectivity >99% with the help of the above rules. [ABSTRACT FROM AUTHOR]

Designing and developing efficient synergistic catalytic systems has always been an exciting topic. In this work, a sandwich-type nanocomposite, UiO-66-NH 2 @Pt@PCN-222, was utilized as a synergistic catalytic system for the selective reduction of nitrobenzaldehydes to nitrobenzyl alcohols. Benefiting from the synergy of PCN-222 and Pt NPs, the catalyst can efficiently promote the formation of 10 nitrobenzyl alcohols under mild conditions within as short as 30 min. Moreover, the PCN-222 provides not only active sites but also protection for metal nanoparticles, so the catalyst remained intact activity in cycles. This work has reference significance for the construction of synergistic catalytic systems. Ultrafast selective hydrogenation reduction of nitrobenzaldehydes to nitrobenzyl alcohols was catalyzed by a stable and synergistic sandwich-type catalyst UiO-66-NH 2 @Pt@PCN-222. [Display omitted] • Ultrafast selective hydrogenation of nitrobenzaldehydes to nitrobenzyl alcohols. • A sandwich-type MOF@Pt@MOF catalyst with synergistic active sites. • Mesoporous MOF, PCN-222, as the active armor of both catalytic activity and protection. [ABSTRACT FROM AUTHOR]

[Display omitted] • Hollow PtCu nanoparticles encapsulated in microporous silica shells were prepared by galvanic displacement replacement. • H-PtCu@SiO 2 nanoreactor shows significantly enhanced catalytic activity and selectivity for benzonitrile hydrogenation. • The reaction can be completed within only 0.5 h, which is the fastest catalytic reaction among the previously reported literature. • The void-confinement effect and limiting diffusion effect of nanoreactor are essential for outstanding catalytic performance. Hollow metal nanoparticles have attracted great interest in heterogeneous catalysis research due to their unique structures as nanoreactors. Here, we report hollow PtCu nanoparticles encapsulated in microporous silica shells (H-PtCu@SiO 2), which can serve as the nanoreactor with high catalytic activity and high stability. The H-PtCu@SiO 2 nanoreactor shows the state-of-the-art catalytic performance for the transfer hydrogenation of benzonitrile to dibenzylamine, which achieves up to 100% conversion and 99% selectivity in only 0.5 h. The void-confinement effect of H-PtCu@SiO 2 is crucial for the outstanding catalytic performance by encaging the reactants in the nanoreactor. The computation demonstrates the limiting diffusion effect of the silica shell toward the ammonia borane, thus reduces the concentration of reductant species and prolongs the lifetime of the intermediate imine to improve the selectivity of secondary amine. Moreover, the silica shells can effectively enhance the catalytic stability of the H-PtCu@SiO 2 nanoreactor. [ABSTRACT FROM AUTHOR]