Communication Issue
NiO@Ni nanoparticles embedded in N-doped carbon for efficient photothermal CO2 methanation coupled with H2O splitting
Nano Research 2024, 17 (4): 2283-2290
Published: 31 October 2023
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Photothermal carbon dioxide (CO2) methanation has attracted increasing interest in solar fuel synthesis, which employs the advantages of photocatalytic H2O splitting as a hydrogen source and photothermal catalytic CO2 reduction. This work prepared three-dimensional (3D) honeycomb N-doped carbon (NC) loaded with core–shell NiO@Ni nanoparticles generated in situ at 500 °C (NiO@Ni/NC-500). Under the photothermal catalysis (200 °C, 1.5 W/cm2), the CH4 evolution rate of NiO@Ni/NC-500 reached 5.5 mmol/(g·h), which is much higher than that of the photocatalysis (0.8 mmol/(g·h)) and the thermal catalysis (3.7 mmol/(g·h)). It is found that the generated localized surface plasmon resonance enhances the injection of hot electrons from Ni to NiO, while thermal heating accelerates the thermal motion of radicals, thus generating a strong photo-thermal synergistic effect on the reaction. The CO2 reduction to CH4 follows the *OCH pathway. This work demonstrates the synergistic effect of NiO@Ni and NC can enhance the catalytic performance of photothermal CO2 reduction reaction coupled with water splitting reaction.

Research Article Issue
Engineering oxygen vacancies and localized amorphous regions in CuO-ZnO separately boost catalytic reactivity and selectivity
Nano Research 2023, 16 (2): 2126-2132
Published: 07 October 2022
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Generating different types of defects in heterogeneous catalysts for synergetic promotion of the reactivity and selectivity in catalytic reactions is highly challenging due to the lack of effective theoretical guidance. Herein, we demonstrate a facile strategy to introduce two types of defects into the CuO-ZnO model catalyst, namely oxygen vacancies (OVs) induced by H2 partial reduction and localized amorphous regions (LARs) generated via the ball milling process. Using industrially important Rochow–Müller reaction as a representative, we found OVs predominantly improved the target product selectivity of dimethyldichlorosilane, while LARs significantly increased the conversion of reactant Si. The CuO-ZnO catalyst with optimized OVs and LARs contents achieved the best catalytic property. Theoretical calculation further revealed that LARs promote the generation of the Cu3Si active phase, and OVs impact the electronic structure of the Cu3Si active phase. This work provides a new understanding of the roles of different catalyst defects and a feasible way of engineering the catalyst structure for better catalytic performances.

Research Article Issue
Dual single-atom Ce-Ti/MnO2 catalyst enhances low-temperature NH3-SCR performance with high H2O and SO2 resistance
Nano Research 2023, 16 (1): 299-308
Published: 11 August 2022
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Mn-based catalysts have exhibited promising performance in low-temperature selective catalytic reduction of NOx with NH3 (NH3-SCR). However, challenges such as H2O- or SO2-induced poisoning to these catalysts still remain. Herein, we report an efficient strategy to prepare the dual single-atom Ce-Ti/MnO2 catalyst via ball-milling and calcination processes to address these issues. Ce-Ti/MnO2 showed better catalytic performance with a higher NO conversion and enhanced H2O- and SO2-resistance at a low-temperature window (100−150 °C) than the MnO2, single-atom Ce/MnO2, and Ti/MnO2 catalysts. The in situ infrared Fourier transform spectroscopy analysis confirmed there is no competitive adsorption between NOx and H2O over the Ce-Ti/MnO2 catalyst. The calculation results showed that the synergistic interaction of the neighboring Ce-Ti dual atoms as sacrificial sites weakens the ability of the active Mn sites for binding SO2 and H2O but enhances their binding to NH3. The insight obtained in this work deepens the understanding of catalysis for NH3-SCR. The synthesis strategy developed in this work is easily scaled up to commercialization and applicable to preparing other MnO2-based single-atom catalysts.

Research Article Issue
Partially charged single-atom Ru supported on ZrO2 nanocrystals for highly efficient ethylene hydrosilylation with triethoxysilane
Nano Research 2022, 15 (7): 5857-5864
Published: 13 April 2022
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Homogeneous noble metal catalysts used in alkene hydrosilylation reactions to manufacture organosilicon compounds commercially often suffer from difficulties in catalyst recovering and recycling, undesired disproportionation reactions, and energy-intensive purification of products. Herein, we report a heterogeneous 0.5Ruδ+/ZrO2 catalyst with partially charged single-atom Ru (0.5 wt.% Ru) supported on commercial ZrO2 nanocrystals synthesized by the simple impregnation method followed by H2 reduction. When used in the ethylene hydrosilylation with triethoxysilane to produce the desired ethyltriethoxysilane, 0.5Ruδ+/ZrO2 showed excellent catalytic performance with the maximum Ru atom utilization and good recyclability, even superior to homogeneous catalyst (RuCl3·H2O). Structural characterizations and density functional theory calculations reveal the atomic dispersion of the active Ru species and their unique electronic properties distinct from the homogeneous catalyst. The reaction route over this catalyst is supposed to follow the typical Chalk–Harrod mechanism. This highly efficient and supported single-atom Ru catalyst has the potential to replace the current homogeneous catalyst for a greener hydrosilylation industry.

Research Article Issue
In-situ growth of heterophase Ni nanocrystals on graphene for enhanced catalytic reduction of 4-nitrophenol
Nano Research 2022, 15 (2): 1230-1237
Published: 09 July 2021
Abstract PDF (24.7 MB) Collect

Generating heterophase structures in nanomaterials, e.g., heterophase metal nanocrystals, is an effective way to tune their physicochemical properties because of their high-energy nature and unique electronic environment of the generated interfaces. However, the direct synthesis of heterophase metal nanocrystals remains a great challenge due to their unstable nature. Herein, we report the in situ and direct synthesis of heterophase Ni nanocrystals on graphene. The heterostructure of face-centered cubic (fcc) and hexagonal close-packed (hcp) phase was generated via the epitaxial growth of hcp Ni and the partial transformation of fcc Ni and stabilized by the anchoring effect of graphene toward fcc Ni nanocrystal and the preferential adsorption of surfactant polyethylenimine (PEI) toward epitaxial hcp Ni. Comparing with the fcc Ni nanocrystals grown on graphene, the heterophase (fcc/hcp) Ni nanocrystals in situ grown on graphene showed a greatly improved catalytic activity and reusability in 4-nitrophenol (4-NP) reduction to 4-aminophenol (4-AP). The measured apparent rate constant and the activity parameter were 2.958 min–1 and 102 min–1·mg–1, respectively, higher than that of the best reported non-noble metal catalysts and most noble metal catalysts. The control experiments and density functional theory calculations reveal that the interface of the fcc and hcp phases enhances the adsorption of substrate 4-NP and thus facilitates the reaction kinetics. This work proves the novel idea for the rational design of heterophase metal nanocrystals by employing the synergistic effect of surfactant and support, and also the potential of creating the heterostructure for enhancing their catalytic reactivity.

Research Article Issue
A general bottom-up synthesis of CuO-based trimetallic oxide mesocrystal superstructures for efficient catalytic production of trichlorosilane
Nano Research 2020, 13 (10): 2819-2827
Published: 05 October 2020
Abstract PDF (29.8 MB) Collect

Mesocrystals, the non-classical crystals with highly ordered nanoparticle superstructures, have shown great potential in many applications because of their newly collective properties. However, there is still a lack of a facile and general synthesis strategy to organize and integrate distinct components into complex mesocrystals, and of reported application for them in industrial catalytic reactions. Herein we report a general bottom-up synthesis of CuO-based trimetallic oxide mesocrystals (denoted as CuO-M1Ox-M2Oy, where M1 and M2 = Zn, In, Fe, Ni, Mn, and Co) using a simple precipitation method followed by a hydrothermal treatment and a topotactic transformation via calcination. When these mesocrystals were used as the catalyst to produce trichlorosilane (TCS) via Si hydrochlorination reaction, they exhibited excellent catalytic performance with much increased Si conversion and TCS selectivity. In particular, the TCS yield was increased 19-fold than that of the catalyst-free process. The latter is the current industrial process. The efficiently catalytic property of these mesocrystals is attributed to the formation of well-defined nanoscale heterointerfaces that can effectively facilitate the charge transfer, and the generation of the compressive and tensile strain on CuO near the interfaces among different metal oxides. The synthetic approach developed here could be applicable to fabricate versatile complicated metal oxide mesocrystals as novel catalysts for various industrial chemical reactions.

Research Article Issue
Rambutan-like hierarchically heterostructured CeO2-CuO hollow microspheres: Facile hydrothermal synthesis and applications
Nano Research 2017, 10 (2): 381-396
Published: 27 October 2016
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Hierarchically heterostructured hollow spheres are of great interest for a wide range of applications owing to their unique structural features and properties. However, the fabrication of well-defined hollow spheres with highly specific morphology for mixed transition metal oxides on a large scale remains challenging. In this work, uniform rambutan-like heterostructured CeO2-CuO hollow microspheres with numerous copper–ceria interfacial sites and nanorods and nanoparticles as building blocks are prepared via a facile hydrothermal method followed by calcination. Importantly, this approach can be readily scaled up and is applicable to the synthesis of various CuO-based mixed metal oxide complex hollow spheres. The as-prepared CeO2-CuO hollow rambutans exhibit superior performance both as electrode materials for supercapacitors and as Cu-based catalysts for the Rochow reaction, mainly due to the small primary nanoparticle constituents, high surface area, and formation of numerous interior heterostructures.

Research Article Issue
One-dimensional Cu-based catalysts with layered Cu–Cu2O–CuO walls for the Rochow reaction
Nano Research 2016, 9 (5): 1377-1392
Published: 29 September 2016
Abstract PDF (3.4 MB) Collect

A series of copper catalysts with a core–shell or tubular structure containing various contents of Cu, Cu2O, and CuO were prepared via controlled oxidation of Cu nanowires (NWs) and used in the synthesis of dimethyldichlorosilane (M2) via the Rochow reaction. The Cu NWs were prepared from copper (Ⅱ) nitrate using a solution-based reduction method. The samples were characterized by X-ray diffraction, thermogravimetric analysis, temperature-programmed reduction, X-ray photoelectron spectroscopy, transmission electron microscopy, and scanning electron microscopy. It was found that the morphology and composition of the catalysts could be tailored by varying the oxidation temperature and time. During the gradual oxidation of Cu NWs, the oxidation reaction initiated on the outer surface and gradually developed into the bulk of the NWs, leading to the formation of catalysts with various structures and layered compositions, e.g., Cu NWs with surface Cu2O, ternary Cu–Cu2O–CuO core–shell NWs, binary Cu2O–CuO nanotubes (NTs), and single CuO NTs. Among these catalysts, ternary Cu–Cu2O–CuO core–shell NWs exhibited superior M2 selectivity and Si conversion in the Rochow reaction. The enhanced catalytic performance was mainly attributed to improved mass and heat transfer resulting from the peculiar heterostructure and the synergistic effect among layered components. Our work indicated that the catalytic property of Cu-based nanoparticles can be improved by carefully controlling their structures and compositions.

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