Research Progress----Shanghai Advanced Research Institute,Chinese Academy of Sciences

Researchers Reveal In-situ Manipulation of Active Au-TiO2 Interface

An international joint research team reported an in-situ strategy to manipulate interfacial structure with atomic precision during catalytic reactions. Results were published in the latest issue of Science.

　　An international joint research team from Zhejiang University, Shanghai Advanced Research Institute of the Chinese Academy of Sciences, and Technical University of Denmark, reported an in-situ strategy to manipulate interfacial structure with atomic precision during catalytic reactions. Results were published in the latest issue of Science.
　　The interface between nanoparticles and substrates plays a critical role in heterogeneous catalysis because most active sites are located at the perimeter of the interface. It is generally believed that this interface is immobile and unchangeable, thus can hardly be adjusted in reactive environments. As a result, it has been challenging to promote catalytic activity through precise control of the interfacial structure.
　　In this study, the scientists first used environmental transmission electron microscopy to directly visualize the epitaxial rotation of gold nanoparticles on titanium dioxide (TiO2) surfaces during CO oxidation at the atomic level. A perfect epitaxial relationship was observed between Au nanoparticles and TiO2 (001) surfaces under an O2 environment in real time.
　　Theoretical calculations including density functional theory calculations and thermodynamics analysis were then carried out, indicating that the epitaxial orientation could be induced by changing O2 adsorption coverage at the perimeter interface. The Au nanoparticle was more stable with adsorption of more O2 molecules at the Au-TiO2 interface, but became less stable with the consumption of O2 with CO.
　　To exploit the promoted activity of Au-TiO2 interface, researchers conducted additional top-view observations and found that this configuration remained unchanged when cooling from 500 °C to 20 °C in CO and O2 reactive environments, showing the rotation of the Au nanoparticle was also temperature dependent in reaction conditions.
　　Taking advantage of the reversible and controllable rotation of the Au nanoparticle, the scientists achieved in-situ manipulation of the active Au-TiO2 interface at the atomic level by changing gas and temperature.
　　This study sheds light on real-time manipulation of catalytic interface structure in reaction conditions at the atomic scale, which may inspire future approaches to real-time design of the catalytic interface under operating conditions.
　　Figure 1. Geometric and electronic structure of Au-TiO2 interface under CO/O2 (A, C, E) and O2 environment (B, D, F) (Image adapted from Science)
　　Figure 2. Manipulation of the Au-TiO2 interface using temperature and gas control (Image adapted from Science)
　　Figure 3. Schematic illustration of In-situ manipulation of active Au-TiO2 interface (Credited by Yong Wang, Zhejiang University)
　　Contact: GAO Yi
　　Shanghai Advanced Research Institute, Chinese Academy of Sciences
　　Email: gaoyi@zjlab.org.cn
　　

2021-01-29 more+

Researchers Develop a Novel Donor-Acceptor System for Highly-effective Sunlight-Driven Hydrogen Evolution

a research team reported a novel photoactive 2D COF from donor Py and acceptor Tz building units, which enabled remarkable photogenerated charge separation and efficient charge migration.

　　Sunlight-driven hydrogen production has been considered as one of the most important renewable energy sources, while active photocatalyst is a prerequisite for efficient hydrogen production. 2D covalent organic frameworks (COFs) could have well-defined arrangements of photo- and electro-active units that serve as electron or hole transport channels for solar energy harvesting and conversion, however, their insufficient charge transfer and rapid charge recombination impede the sunlight-driven photocatalytic performance.
　　Motivated by such a challenge, a research team led by Prof. WEN Ke and Prof. YANG Hui at Shanghai Advanced Research Institute (SARI), collaborated with Prof. ZHANG Yue-Biao at ShanghaiTech University reported a novel photoactive 2D COF from donor Py and acceptor Tz building units, which enabled remarkable photogenerated charge separation and efficient charge migration. The research results were featured on front cover of Angewandte Chemie International Edition.
　　Based on physical structural characterizations, scientists conjectured that Thiazolo[5,4-d]Thiazole might help to boost photo-absorbing ability of previously reported TpTz COF and constructed the new donor-acceptor system from the electron-rich pyrene (Py) and electron-deficient thiazolo[5,4-d]thiazole (Tz). The PyTz-COF demonstrated high photocatalytic activitity for sustainable and efficient water splitting with a photocurrent up to 100 uA cm-2 at 0.2 V vs. RHE and could reach a hydrogen evolution rate of 2072.4 umolg-1 h-1, which exceeds the values of many previously reported COFs.
　　This study not only realized the effective separation and migration of photogenerated electrons and holes, but also revealed a new mechanism of COF photocatalysis. More importantly, it would inspire future development of sunlight-driven photocatalysts for solar energy harvesting and conversion.
　　Figure 1. Synthetic route for PyTz-COF (Image by SARI)
　　Figure 2. Photoelectrochemical and photocatalytic performance of PyTz-COF (Image by SARI)
　　Contact: Prof. Wenke
　　Shanghai Advanced Research Institute, Chinese Academy of Sciences
　　Email: wenk@sari.ac.cn
　　

2021-01-22 more+

Scientists Reveal New Tools in Single-cell Infrared Microspectroscopy Based on Synchrotron Radiation

Single-cell technologies are becoming hot topics and key directions of biomedical research due to their abilities to answer the basic question of cellular functional heterogeneity and to interpret the molecular basis of various chronic diseases as well as aging. Among the single cell techniques, single-cell infrared spectroscopy obtains growing attention because of its advantages in simultaneously identifying the characteristics of intracellular metabolites. Recently, research team at Shanghai Advanced Research Institute together with collaborators have successfully revealed new tools to evaluate single-cell infrared data based on synchrotron radiation.

　　Single-cell technologies are becoming hot topics and key directions of biomedical research due to their abilities to answer the basic question of cellular functional heterogeneity and to interpret the molecular basis of various chronic diseases as well as aging. Among the single cell techniques, single-cell infrared spectroscopy obtains growing attention because of its advantages in simultaneously identifying the characteristics of intracellular metabolites.
　　Recently, Professor Lü Junhong’s group at Shanghai Advanced Research Institute (SARI), collaborating with Shanghai Center for Bioinformation Technology, National Engineering Research Center for Nanotechnology, Capital Medical University Tiantan Hospital, Binzhou Medical University and Shanghai Jiao Tong University Ruijin Hospital, have successfully revealed new tools to evaluate single-cell infrared data based on synchrotron radiation.
　　Fourier Transform infrared (FTIR) spectroscopy is a well-established non-destructive and sensitive analytical technique for the study of biological samples. Due to the inevitable technical errors/variation (caused by water vapor, CO2, instrument noise, etc.) or batch effects, a significant number of cells must be analyzed in order to distinguish the measured signal from controls with statistical confidence. Therefore, estimating a reasonable and practical amount for single-cell infrared spectroscopy is particularly necessary.
　　To this end, the group has developed a statistical method and procedure to evaluate single-cell spectral variability among two different cell types and two states. After calculating the similarity distance of the corresponding infrared spectra, they confirmed that 20 cells measured per time is sufficient to control batch effects (CV < 5%).
　　These findings provide a useful tool to evaluate the single-cell spectral quality and an important benchmark for the investigation of cellular heterogeneity.
　　Figure 1 Batch effects on single-cell infrared spectra and the establishment of evaluation methodology (Image adapted from Chemical Communications)
　　Cell phenomics is an emerging field that simultaneously characterizes many phenotypic traits of cells in response to genetic mutation and environmental influences. The group has proposed a label-free phenotypic screening strategy based on the combination of single-cell infrared microspectroscopy and the statistical calculations of the similarity among single cell infrared spectra.
　　This novel approach enables subtle phenotypic changes to be unveiled within individual cells by using comprehensive analysis of spectral similarity in chemical components. Based on this infrared phonemics method, they demonstrate for the first time phytomedicine protopanaxadiol with different concentration induces phenotypical changes of cancer cell HepG2.
　　These findings provide a powerful tool to accurately evaluate the cell stress responses and to largely expand the phenotypic screening toolkit for drug discovery.
　　Figure 2 Single-cell infrared phenomics and drug screening (Image adapted from Chemical Communications)
　　With the rapid technological advances, a variety of single-cell methods are emerging for the promise of unveiling cellular heterogeneity. The demand of a detailed and unbiased approach to simultaneously quantify global biomolecular structure information in a single cell and heterogeneity within cells is urgent.
　　The research group developed a novel strategy to quantitatively evaluate cellular heterogeneity based on single-cell synchrotron FTIR microspectroscopy and computational methods. After calculating the cell-to-cell similarity distance of the infrared spectral data, they confirmed that the statistical analysis of single-cell infrared phenotypes can be used to quantify the heterogeneity in a specific cell population. Based on this method, they revealed the infrared phenotypes have a similar tendency with increasing heterogenicity at the early stage and decreasing heterogenicity at the terminal stage of differentiation toward adipocyte lineage.
　　These findings provide an alternative methodology for dissecting the cellular heterogeneity, and the combination with other single-cell analysis tools will be very helpful for understanding the genotype-to-phenotype relationship in cellular populations.
　　Figure 3 Sing-cell infrared microspectroscopy quantifies dynamic heterogeneity of Mesenchymal stem cells during adipogenic differentiation (Image adapted from Analytical Chemistry)
　　These findings were published on Chemical Communications (2020,26:3773-3776;2020,86:13237-13240) and Analytical Chemistry (2020,10.1021/acs.analchem.0c04110) respectively.
　　These works were supported by the National Natural Science Foundation of China and from the BL01B beamline of the National Facility for Protein Science in Shanghai (NFPS) at Shanghai Synchrotron Radiation Facility.
　　Contact: Lü Junhong
　　Shanghai Advanced Research Institute, Chinese Academy of Sciences
　　Email: lujunhong@zjlab.org.cn

2021-01-05 more+

Novel compound/c-Si passivation contact for p‐Type Crystalline Silicon Solar Cells Achieving 20% Efficiency

Crystalline silicon heterojunction solar cells based on hole-selective MoOX contacts provide obvious merits in terms of the decent passivation and carrier selectivity but face the challenge of long-term stability. With the aim to improve the performance and stability of solar cells with full area MoOX/ metal contacts, a SiOX tunneling layer on silicon surface is intentionally formed by UV/O3 treatment and an indium tin oxide (ITO) film is sputtered as a high-work-function electrode.

　　Efficient separation and collection of photogenerated carriers through the formation of asymmetric electron and hole transport channels is one of the central issues for crystalline silicon (c-Si) solar cells and other types of photovoltaic devices. Silicon heterojunction solar cells based on MoOX (X<3) hole-selective contacts show significant advantages in carrier-selective transport, however, it faces the challenge for long-term stability due to poor thermodynamic stability of MoOX.
　　Motivated by such a challenge, a research team led by Prof. LI Dongdong at Shanghai Advanced Research Institute (SARI) of the Chinese Academy of Sciences collaborated with Jinneng Clean Energy Technology Limited reported a novel stacked structure (c-Si/SiOX/MoOX/V2OX/ITO/Ag) to improve the stability of c-Si solar cells. The research results were published in Advanced Functional Materials entitled “Stable MoOX‐Based Heterocontacts for p‐Type Crystalline Silicon Solar Cells Achieving 20% Efficiency”.
　　In this work, the research team introduced a SiO2 tunneling passivation layer at the MoOX/c-Si interface to suppress the redox reaction brought about by the direct contact between MoOX and c-Si, which keeps the work function of MoOX at a relatively high level. An ultra-thin V2OX layer is deposited on the surface of MoOX film to improve the stability of the heterojunction structure in air and its resistance to sputtering damage. At the same time, the ITO layer is fabricated at the V2OX/Ag interface, which effectively inhibits the migration of metal ion, and finally constructs a tandem structure of c-Si/SiOX/MoOX/V2OX/ITO/Ag, with power conversion efficiency (PCE) of 20.0% and significantly improved stability.
　　This work innovatively constructs a stacked thin film structure based on an in-depth understanding of the interfacial evolution of MoOX/c-Si and MoOX/metal electrodes, providing a new approach to the study of compound/c-Si passivated contact heterojunction solar cells, which can be extended as a universal method to improve the efficiency and stability of heterojunction solar cells and other types of optoelectronics.
　　This work was supported by the National Natural Science Foundation of China, the Natural Science Foundation of Shanghai, the Shanxi Science and Technology Department, and the Youthnnovation Promotion Association of the Chinese Academy of Sciences.
　　
　　Figure 1. The device performances as a function of UV/O3 pre-treatment (Image adapted from Advanced Functional Materials)
　　Figure 2. Characterizations of XPS spectra and passivation properties of MoOX films (Image adapted from Advanced Functional Materials)
　　Contact: LI Dongdong
　　Shanghai Advanced Research Institute, Chinese Academy of Sciences
　　Email: lidd@sari.ac.cn
　　

2020-09-22 more+

Researchers Develop Integrative Treatment of Tumor-related Bone Defects

Malignant bone tumors have caused great obstacles and serious illnesses for tumor recurrence and difficulty in reconstructing and repairing large defeats after tumorectomy due to the poor prognosis for metastatic relapse or recurrence for patients with the axial disease. In a study published in Chemical Engineering Journal, a research team from the Shanghai Advanced Research Institute (SARI) of the Chinese Academy of Sciences (CAS) reported a novel therapeutic treatment of anti-tumor/bone repair by combination of MoS2 nanosheets with 3D printed bioactive borosilicate glass scaffolds.

　　Malignant bone tumors have caused great obstacles and serious illnesses for tumor recurrence and difficulty in reconstructing and repairing large defeats after tumorectomy due to the poor prognosis for metastatic relapse or recurrence for patients with the axial disease.
　　In a study published in Chemical Engineering Journal, a research team led by Prof. LI Jiusheng from the Shanghai Advanced Research Institute (SARI) of the Chinese Academy of Sciences (CAS), collaborated with Shanghai Jiao Tong University Affiliated Sixth People’s Hospital, Shenzhen University, etc. reported a novel therapeutic treatment of anti-tumor/bone repair by combination of MoS2 nanosheets with 3D printed bioactive borosilicate glass scaffolds.
　　Based on the proof of concept of “integrative treatment”, scientists reported for the first time on the concept of “integrative treatment” on local combating tumor and bone tissue repairing by integrating anti-tumor/bone repair functions together by fixing MoS2 on the surface of materials. The material’s properties, bioactive ability, photothermal stability and capability, osteogenesis and the anti-tumor ability of BGM composite scaffolds in vitro and vivo were later evaluated and investigated in this study.
　　The MoS2-integrated composite BG (BGM) scaffolds can rapidly and effectively elevate temperature, and they exhibited excellent photothermal stability. Notably, the BGM scaffolds can effectively reduce the viability of osteosarcoma cells (MNNG/HOS) in vitro as well as inhibit the tumor growth in nude mice. Furthermore, the prepared BGM scaffolds can stimulate the proliferation and differentiation of rat bone mesenchymal stem cells (rBMSCs), upregulate the expression of osteogenesis-related genes in vitro and promote in vivo bone repair in critical-sized rat calvarial defects.
　　Therefore, the “integrative treatment” BGM scaffolds have great potential to be applied in the treatment of anti-tumor and bone repair, offering ideas for the manufacture of new materials in the tissue engineering field.
　　Schematic diagram for investigation on the integrative treatment of anti-tumor/bone repairing with 3D printing BGM scaffolds (Image by SARI)
　　The study was supported by the National Natural Science Foundation, China (Grant Nos. 51802326) and Youth innovation promotion association of Chinese Academy of Sciences (Grant No. 2020292).
　　Contact: Wang Hui
　　Shanghai Advanced Research Institute, Chinese Academy of Sciences
　　Email: wanghui01@sari.ac.cn

2020-07-17 more+

New Light-based Method Proposed for C(sp3)–H Functionalizations of Light Hydrocarbons

Intrinsic inertness of gaseous hydrocarbons requires harsh reaction conditions to enable C(sp3)–H bond cleavage, resulting in low-yielding and unselective transformation to high-value added chemicals. Motivated by such a challenge, a team collaborated by researchers from Eindhoven University of Technology, ShanghaiTech University and Shanghai Advanced Research Institute (SARI) of the Chinese Academy of Sciences reported a general and mild strategy to directly activate alkanes using decatungstate photocatalysis in flow.

　　Intrinsic inertness of gaseous hydrocarbons (e.g., ethane and methane) requires harsh reaction conditions to enable C(sp3)–H bond cleavage, resulting in low-yielding and unselective transformation to high-value added chemicals. Therefore, direct activation of gaseous hydrocarbons remains a major challenge for the chemistry community.
　　Motivated by such a challenge, a team collaborated by researchers from Eindhoven University of Technology, ShanghaiTech University and Shanghai Advanced Research Institute (SARI) of the Chinese Academy of Sciences reported a general and mild strategy to directly activate alkanes using decatungstate photocatalysis in flow. The study was published in the latest issue of Science on July 3.
　　The newly developed method aims to irradiate the molecules with light in the presence of a suitable catalyst, thereby immediately converting low-weight hydrocarbons into more complex molecules at room temperature and low pressure. To achieve that, researchers had to address the following challenges: first, the cleavage of very strong aliphatic C–H bonds with a bond dissociation energy (BDE) between 96.5 and 105 kcal mol-1 (Figure 1B) and second, appropriate technologies to bring the alkanes and catalyst into close proximity with a suitable catalyst and reaction partner.
　　Given the photoexcited decatungstateanion (W10O324-) has enabled a number of synthetically useful C(sp3)–H functionalizations, scientists reasoned that the use of flow technology is indispensable to facilitate the gas-liquid decatungstate-mediated processes. Through investigation to optimize reaction conditions and transformation scope, scientists solved these two problems by exciting the alkanes with UV light (about 365 nm) in the presence of a suitable catalyst tetrabutylammonium decatungstate (TBADT) in flow.
　　This new method paves the way for the inexpensive production of some medicines, in view of the low cost of catalysts to activate the gaseous alkanes and simplification of reactions. Further research is needed to apply intensified reactors to increase production capacity.
　　Fig. 1 Decatungstate enables the direct C(sp3)–H activation of light hydrocarbons. (Image adapted from Science)
　　Contact: SUN Yuhan
　　Shanghai Advanced Research Institute, Chinese Academy of Sciences
　　Email: sunyh@sari.ac.cn

2020-07-10 more+