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104. Synthesis of a ruthenium–graphene quantum dot–graphene hybrid as a promising single-atom catalyst for electrochemical nitrogen reduction with ultrahigh yield rate and selectivity

Author

Li Nana, He Keyang, Wang Wendong, Zhu Haiyan, Li Ruiyi, Xu Pengwu, Li Zaijun, and Liu Xiaohao

Subjects
Materials science, Renewable Energy, Sustainability and the Environment, Graphene, Oxide, chemistry.chemical_element, General Chemistry, Electrochemistry, Ascorbic acid, Graphene quantum dot, Catalysis, Ruthenium, law.invention, chemistry.chemical_compound, chemistry, Chemical engineering, law, General Materials Science, Faraday efficiency
Abstract

It is impossible for the hybrid of classical graphene and metal nanoparticles to break through the limitations of their inherent properties because graphene and metal nanoparticles are conductors. This study reports the synthesis of single atom ruthenium–histidine-functionalized graphene quantum dot–graphene hybrid (Ru–His–GQD–G). His–GQD is immobilized on graphene oxide (GO) via π–π stacking and then coordinated with Ru3+ ions. This is followed by reduction with ascorbic acid into GO gel and annealing at 400 °C at a slow heating rate of 0.5 °C min−1. The resulting Ru–His–GQD–G shows a well-defined three-dimensional structure with a high Ru loading of 5.1 wt%, in which Ru atoms are evenly dispersed on graphene sheets. The intimate contact between His–GQD and Ru atom and graphene creates double Schottky heterojunctions. Ru–His–GQD–G exhibits ultrahigh catalytic activity for electrochemical nitrogen reduction. At a low potential of −0.05 V, the NH3 yield rate reaches 226 μg mg−1 h−1 with the faradaic efficiency of 42.6%, which is better than that of reported electrocatalysts for nitrogen reduction. The experimental and theoretical investigations demonstrate that the Ru sites with His–GQD are the major active centers that permit nitrogen adsorption, stabilization of *NNH and destabilization of *H. This study also provides a way for the construction of graphene-based single-atom catalysts with excellent catalytic activity.

Published
2021
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113. Additional file 1 of Collagen-induced assembly of adenosine monophosphate-modified gold nanoparticles for photothermal cancer therapy

Author

Qu, Xinyu, Chen, Yixing, Cai, Zhuyun, Zhao, Xinyu, Zeng, Hua, Liu, Xiaohao, Tan, Shuo, Lu, Bingqiang, Gao, Rui, and Chen, Feng

Abstract

Additional file 1: Figure S1. Zeta potential of AAu sample. Figure S2. Photothermal conversion efficiency of the AAu sample at different laser powers and different AAu concentrations. Figure S3. Temperature changes of CAAu NPs suspensions upon multiple laser on/off cycles (808 nm, 1.5 W). Figure S4. (A) The TEM image and (B) absorption spectrum of the CAAu after irradiation with 808 laser for 10 min. Figure S5. Snap photos of B16-F10 cells after co-incubation with AAu NPs for 24 h at different time intervals: (A) 0 s; (B) 1 s; (C) 2 s; and (D) 3 s, showing that the cell can actively grasp the AAu material, which indicates that the AAu NPs has good biocompatibility. Figure S6. The cytotoxicity of AAu to B16-F10 cells under near-infrared radiation was evaluated. (A) Fluorescent images of B16-F10 cells co-incubated with AAu NPs at the concentration of 20 μg/mL for 2 h with or without irradiation of an 808 nm NIR laser at various power densities (power: 0, 0.5, 1.5 and 2.5 W; spot size: 0.785 cm2). (B) Fluorescent images of B16-F10 cells co-incubated with AAu NPs at various concentrations (i.e., 0, 5, 10, 20 and 40 μg/mL) for 2 h with or without laser irradiation (power: 1.5 W; spot size: 0.785 cm2). (C) Fluorescent images of B16-F10 cells co-incubated with AAu NPs at the concentration of 20 μg/mL for 2 h with or without laser irradiation (power: 1.5 W; spot size: 0.785 cm2) for various time (i.e., 0, 0.5, 1, 2, 5, 10 min). The cells were stained to show living (green) and dead cells (red) under fluorescence microscope. Figure S7. Fluorescent images of live (green) and dead cells (red) after co-incubation with AAu nanoparticles with various concentrations (i.e., 0, 5, 10, 20 and 40 μg/mL) for different time: (A) 24 h or (B) 48 h. Scale bar: 200 μm. Figure S8. Schematic illustration of the animal experimental design of the photothermal therapy for melanoma. Figure S9. The Au elemental concentration normalized to mass of different organs taken from one mouse on the day 10 (i.e., one day after the last treatment). The relatively high Au amount in kidney indicates that the AAu NPs can be excreted from the body through kidney due to its small size. Table S1. The calculated extinction coefficients (L·mmol–1·cm–1) of AAu and CAAu [1].

Published
2022
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116. Advanced Li/Na–CO2Batteries Enabled by the γ-MnO2Catalyst with Enhanced Carbonate Decomposition

Author

Chen, Xiaoyang, Chen, Jian, Liu, Yijie, Liu, Yang, Gao, Yun, Fan, Siwei, He, Xiangxi, Liu, Xiaohao, Shen, Chao, Jiang, Yong, Li, Li, Qiao, Yun, and Chou, Shulei

Abstract

Metal–CO2batteries, especially Li–CO2and Na–CO2batteries, are regarded as ideal new-generation energy storage systems owing to their high energy density and extraordinary CO2capture capability. However, the advancement of metal–CO2batteries is still at an early stage. The problems caused by accumulation of carbonates during charge–discharge cycles, such as large polarization and poor reversibility, restrict their practical application. Therefore, designing efficient catalysts is crucial for promoting the decomposition of carbonate to improve the electrochemical performance of metal–CO2batteries. Herein, we first adopted sea urchin-like γ-MnO2as the cathode material for Li/Na–CO2batteries. Benefiting from the unique structure and excellent catalytic activity of γ-MnO2, the as-prepared Li–CO2and Na–CO2batteries can achieve low overpotentials of 1.28 and 1.36 V, respectively, at a current density of 100 mA g–1with a cutoff capacity of 1000 mA h g–1. The overpotentials are lower than those of most of the state-of-the-art catalysts in previous reports. After 100 and 50 cycles of Li–CO2and Na–CO2batteries, respectively, their charging termination voltages remain at around 4.1 and 3.9 V, respectively; such a low charging platform indicates the excellent catalytic activity of the γ-MnO2cathode on the discharge products. Our findings offer a promising guideline to design efficient electrocatalysts for high-performance metal–CO2batteries.

Published
2023
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132. Ti‐doped CeO2 Stabilized Single‐Atom Rhodium Catalyst for Selective and Stable CO2 Hydrogenation to Ethanol.

Author

Zheng, Ke, Li, Yufeng, Liu, Bing, Jiang, Feng, Xu, Yuebing, and Liu, Xiaohao

Subjects
RHODIUM catalysts, HYDROGENATION, ETHANOL, COUPLING reactions (Chemistry), SCISSION (Chemistry), CERIUM oxides, CARBON dioxide
Abstract

Development of effective and stable catalysts for CO2 hydrogenation into ethanol remains a challenge. Herein, we report that Rh1/CeTiOx single‐atom catalyst constructed by embedding monoatomic Rh onto Ti‐doped CeO2 support has shown a super high ethanol selectivity (≈99.1 %), record‐breaking turnover frequency (493.1 h−1), and outstanding stability. Synergistic effects of Ti‐doption and monoatomic Rh contribute to this excellent catalytic performance by firstly facilitating oxygen vacancies formation to generate oxygen‐vacancy‐Rh Lewis‐acid‐base pairs, which favor CO2 adsorption and activation, cleavage of C−O bonds in CHxOH* and COOH* into CHx* and CO* species, subsequent C−C coupling and hydrogenation into ethanol, and secondly generating strong Rh−O bond by Ti‐doping‐induced crystal reconstruction, which contributes to striking stability. This work highlights the importance of support elaborating regulation for single‐atom catalyst design to substantially improve the catalytic performance. [ABSTRACT FROM AUTHOR]

Published
2022
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135. Catalytic Activity for CO2 Hydrogenation is Linearly Dependent on Generated Oxygen Vacancies over CeO2‐Supported Pd Catalysts.

Author

Jiang, Feng, Wang, Shanshan, Xu, Yuebing, Liu, Bing, and Liu, Xiaohao

Subjects
CATALYTIC activity, HYDROGENATION, CATALYSTS, CHEMICAL properties, CARBON dioxide, OXYGEN
Abstract

CO2 hydrogenation to methanol is a promising way to achieve the utilization of CO2 to high‐value chemicals. Promoters are frequently applied to regulate the chemical and physical properties of catalysts, but their critical role in selective CO2 hydrogenation toward methanol over Pd/CeO2 is still far from clear. In this work, a series of promoters including La, Zr, Cr, Ca, Co, Cd, Zn, Bi, and K are selected to co‐impregnate with Pd precursor on ceria nanorods to reveal their impact on CO2 hydrogenation performance. It turns out that the catalytic activity over Pd/CeO2 catalyst is linearly dependent of the amount of created oxygen vacancies which determines by the nature of promoter. Especially, the introduction of Zr could incorporate into ceria lattice for the facile formation of oxygen vacancies, thus notably enhancing the catalytic activity with slightly higher methanol selectivity. [ABSTRACT FROM AUTHOR]

Published
2022
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139. The role of water vapour on CO2mobility on calcite surface during carbonation process for calcium looping: A DFT study

Author

Zha, Jianrui, Yan, Yongliang, Ma, Peiyong, Huang, Yaji, Qi, Fenglei, Liu, Xiaohao, Diao, Rui, and Yan, Dongxu

Abstract

The presence of water vapour has been proven to stimulate carbonation for the calcium looping process, while its effect mechanism during the slow reaction stage still lacks insight understanding at the atomic level, where H2O molecules may interact with the product layer to affect the transportation of CO2. This study tried to reveal the role of water vapour on CO2mobility on the calcite surface through density functional theoretical (DFT) calculation. H2O molecule has higher adherence to calcite surface than CO2, and it can react with CO3to generate HCO3−and OH−ions. Then, the formed OH−ion above the surface layer can adsorb CO2. Moreover, H2O can also react with O2−defect to form OH−ions, and the OH ion at the deeper position can still adsorb CO2through a two-step process with remarkable energy barriers. However, the formation of HCO3−can degrade the energy barriers to CO2release from the calcite surface, owning to the weaker CO bond. Two directions of CO2movement between anions were involved in this investigation, including crossing through the surface layer to the second layer and the movement inside the surface layer, where the higher mobility of CO2from HCO3−to O2−ion occurs in both movement directions. For the case inside the surface layer, the movement from O2−ion to HCO3−has a higher energy barrier, indicating that the stimulation by H2O is a one-way effect, and the enhancement by H2O for CO2mobility is caused by the reaction with CO32−other than O2−ion.

Published
2024
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146. Ultra‐stable Molecular Interface SiW12Ox/TiO2 Catalyst Derived from Keggin‐type Polyoxometalates for Photocatalytic Conversion of Methane to Oxygenates.

Author

Sun, Helong, Hu, Lufa, Li, Zhangyang, Lang, Junyu, Wang, Chunling, Liu, Xiaohao, Hang Hu, Yun, and Jin, Fangming

Subjects
MOLECULAR structure, POLYOXOMETALATES, BRONSTED acids, CATALYSTS, CATALYTIC activity
Abstract

The interface and surface acidity of heterogeneous catalysts are widely applied to manipulate the catalytic performance. However, the interface structure prepared by traditional synthesis processes required multistep procedures, which was still lack of controllability and stability. Here, we show a general synthetic approach to fabricate ultra‐stable heterogeneous catalysts with tailored molecular interfacial structure and super acidity in one step. The as‐synthesized SiW12Ox/TiO2 catalyst was used for photo‐catalytic conversion of methane to value‐added oxygenates. We propose that the formed molecular interface W12−OH−Ti coupled with the introduced Brønsted acid sites of POMs, results in enhancing the photocatalytic performance. Namely, the addition of SiW12Ox can reduce the recombination of electrons and holes for triggering charge separation owing to the photoelectron capturing by proton, improving electron transfer to reactants and thereby promoting catalytic activity. This fabrication method provides a way to build molecular interface photo‐catalyst by POMs with super acidity and ultra‐stable structure. [ABSTRACT FROM AUTHOR]

Published
2022
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