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

Researchers Developed a Novel Graphene/Silicon Catalyst for Highly Selective Photoelectroreduction of Carbon Dioxide to Ethanol

a research team led by Profs. CHEN Wei and WEI Wei from the Shanghai Advanced Research Institute (SARI) of the Chinese Academy of Sciences reported efficient CO2 photoelectroreduction to ethanol (C2H5OH) over graphene/silicon carbide (SiC) catalysts under simulated solar irradiation with ethanol (C2H5OH) selectivity of >99% and a CO2 conversion rate of up to 17.1mmol gcat-1h-1. The results were published in Angew. Chem. Int. Ed.

Using sunlight to produce valuable chemicals and fuels from carbon dioxide (CO2), i.e., artificial photosynthesis (AP) is a promising strategy to achieve solar energy storage as well as a negative carbon cycle.However, the AP is quite complex and involves multiple sequential and parallel steps. What’s more, thermodynamically favorable C1 products can be produced from multiple AP intermediates, making it challenging to selectively produce target chemicals containing C-C bonds. Therefore, selective synthesis of C2 compounds with a high CO2 conversion rate remains challenging for current AP technologies.Motivated by such a challenge, a research team led by Profs. CHEN Wei and WEI Wei from the Shanghai Advanced Research Institute (SARI) of the Chinese Academy of Sciences reported efficient CO2 photoelectroreduction to ethanol (C2H5OH) over graphene/silicon carbide (SiC) catalysts under simulated solar irradiation with ethanol (C2H5OH) selectivity of >99% and a CO2 conversion rate of up to 17.1mmol gcat-1h-1.The results were published in Angew. Chem. Int. Ed.A graphene/silicon carbon (SiC) composite catalyst, which comprises a SiC substrate, interfacial layer (IL), and few-layer graphene overlayer can help to achieve the precise control of active intermediates for C？C coupling. An optimal IL structure allows photogenerated electrons from the SiC substrate to be facilely transferred to the active sites on the graphene overlayer. Reaction intermediates can then be efficiently formed and stabilized owing to their strong adsorption at the active sites and the high electron density of the graphene surface.Experimental results and first principles calculations show that CH3OH formation is largely suppressed in favor of C-C coupling. C2H5OH is therefore exclusively formed with a selectivity of>99% and a CO2 conversion rate of 17.1mmol gcat-1h-1 under simulated solar irradiation with a small bias (-50 mV bias vs. Ag/AgCl) and ambient conditions. Thus, the photoelectrocatalytic performance of the optimal catalyst in producing C2 products from CO2 was at least two orders of magnitude higher than those of the state-of-the-art AP catalysts.This work paves the way toward an advanced AP strategy to efficiently valorize greenhouse CO2.
　　Figure1. Schematic diagram a for highly selective photoelectroreduction of carbon dioxide over graphene/silicon carbide composites (image by SARI)
　　Figure 2. Synthetic Scheme, Raman spectra and CO2 photoelectrocatalytic performances. (image by SARI)
　　

2023-03-20 more+

Researchers Propose an Effective and Reusable Tandem Catalyst for Plastic Waste Conversion

a research group led by Prof. WANG Hui and Associate Prof. LUO Hu at the Shanghai Advanced Research Institute, Chinese Academy of Sciences developed a tandem catalytic reaction to efficiently convert low-density polyethylene (LDPE) into naphtha, where a naphtha yield of 89.5% is obtained with 96.8% selectivity of C5？C9 hydrocarbons at 250 °C, catalyzed by mechanically mixed β zeolite and Pt@S-1 catalysts.The research results were published in Journal of the American Chemical Society recently.

　　The rapid growth of plastic waste is an ever-growing environmental and energy challenge. Selectively converting waste plastics to naphtha, a main feedstock for ethylene and the plastic industry, shows high potential to partially replace petroleum-route naphtha and alleviate global net carbon emissions. However, these active metals on supported catalysts with an open microenvironment showed less effect on the generation of intermediates and selectivity of naphtha.
　　Motivated by such a challenge, a research group led by Prof. WANG Hui and Associate Prof. LUO Hu at the Shanghai Advanced Research Institute, Chinese Academy of Sciences developed a tandem catalytic reaction to efficiently convert low-density polyethylene (LDPE) into naphtha, where a naphtha yield of 89.5% is obtained with 96.8% selectivity of C5-C9 hydrocarbons at 250 °C, catalyzed by mechanically mixed β zeolite and Pt@S-1 catalysts.
　　The research results were published in Journal of the American Chemical Society recently.
　　The selectivity of normal alkanes catalyzed by Pt@S-1 and β zeolite reached 34%, about 10-20% higher than that on Pt/S-1, and the alkane products were narrower. The differences between the two catalysts were possibly due to the confinement effect and shape-selectivity of Pt@S-1. Thus, combined density functional theory (DFT) and molecular dynamics simulations were used to reveal the shape-selectivity process, as the diffusion and shipping of olefin intermediates with the right size were boosted within Pt@S-1, which led to narrower-distributed products.
　　This catalyst system displayed stability and high performance for most abundant plastic waste like low-/high-density polyethylene and polypropylene at moderate conditions. With life cycle assessment (LCA), this approach showed 15% energy saving and 30% reduced greenhouse gas emissions compared with conventional routes for plastic production.
　　This work provides an upgrading strategy for retaining the value of waste plastics more efficiently and serving as a significant step to realize the circular economy.
　　DFT and molecular dynamics calculations (image by SARI)
　　

2023-01-19 more+

Researchers Propose a Novel Ordered MEA for High-performance PEMWE

a research team led by Prof. YANG Hui at Shanghai Advanced Research Institute (SARI) of the Chinese Academy of Sciences reported a novel ordered MEA based on anode with 3D membrane/catalytic layer (CL) interface and gradient tapered arrays, which not only greatly increases the electrochemical active area but also decreases the overpotentials of both mass transport and ohmic polarization.The research results were published in Nano Letters recently.

Proton exchange membrane water electrolysis (PEMWE) is under intensive investigation because of its advantages as high energy efficiency and hydrogen purity compared to the conventional alkaline water electrolysis. However, as the practical application of the PEMWEs usually runs at high current densities ( ≥1-2 A m-2), insufficient catalyst utilization, limited mass transport and high ohmic resistance of the conventional membrane electrode assembly (MEA) restrict the performance of PEMWE.
　　Motivated by such a challenge, a research team led by Prof. YANG Hui at Shanghai Advanced Research Institute (SARI) of the Chinese Academy of Sciences reported a novel ordered MEA based on anode with 3D membrane/catalytic layer (CL) interface and gradient tapered arrays, which not only greatly increases the electrochemical active area but also decreases the overpotentials of both mass transport and ohmic polarization.
　　The research results were published in Nano Letters recently.
　　An overall design of the MEA based on anode with ordered arrays, gradient CL and 3D membrane/CL interface structure was proposed and confirmed by scanning electron microscopy, energy disperse spectroscopy and X-ray photoelectron spectroscopy.
　　Benefiting from the maximized triple-phase interface, rapid mass transport and gradient CL, such an ordered structure not only greatly increases the electrochemical active area by 4.2 times but also decreases the overpotentials of both mass transport and ohmic polarization by 13.9% and 8.7%, respectively.
　　This ordered MEA ensures a performance of 1.801 V @ 2 A cm-2 even with Ir loading as low as 0.2 mg cm-2, which is comparable with conventional MEA with Ir loading of 2 mg cm-2. Further, it can operate stably over 300 h under 1 A cm-2.
　　The study provides a simple but effective strategy for the overall design of nanostructured MEA for high-performance and stable PEMWE with low Ir loading.
　　Structure and performance of the prepared MEA-GTAs-T1 (Image by SARI)
　　

2023-01-09 more+

Researchers Design a Novel Copper Gas Penetration Electrode to Efficiently Reduce CO2 to Multicarbon Products

a research team from the Shanghai Advanced Research Institute of the Chinese Academy of Sciences reported a hierarchical micro/nanostructured Cu(100)-rich hollow-fiber gas penetration electrode (GPE), breaking through the bottleneck of low CO2 solubility limit and realizing electrochemical reduction of CO2 to multicarbon products under ampere level current density.

2022-11-08 more+

Researchers Constructed Bifunctional Catalysts with Redox-active Sites for Oxygen Reduction and Oxygen Evolution Reaction

Recently, a research team led by Prof. ZENG Gaofeng and Associate Prof. XU Qing at the Shanghai Advanced Research Institute (SARI) of the Chinese Academy of Sciences constructed a novel bifunctional COFs towards ORR and OER by combining redox-active units with catalytic centers in the frameworks.

　　It is essential to develop bifunctional oxygen electrocatalysts which exhibit high activity for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER).
　　Covalent organic frameworks (COFs), which possess ordered pores and high-precision functionalization, have been used in electrochemical energy and conversion systems because of their fast ion transport channels and well-defined electrochemical active sites.
　　However, the limited electron transport ability along the frameworks hindered their electroactivities, while the development of active sites in COFs towards ORR and OER is rarely explored.
　　Recently, a research team led by Prof. ZENG Gaofeng and Associate Prof. XU Qing at the Shanghai Advanced Research Institute (SARI) of the Chinese Academy of Sciences constructed a novel bifunctional COFs towards ORR and OER by combining redox-active units with catalytic centers in the frameworks. The COFs showed higher catalytic activities than that of the COF without redox-active units, with a halfwave potential of 0.80 V towards ORR, and an overpotential of 420 mV for OER in 0.1 M KOH, respectively.
　　The research results were published in Angewandte Chemie International Edition on Oct. 14.
　　Two novel COFs (CoTAPP-PATA-COF and CoTAPP-BDTA-COF) have ordered structure, high surface area and stable chemical stability. The diamine unit, as a typical electron donor and redox-active core, facilitates the electron transport along the framework and improves the electrochemical active surface area.
　　The theoretical calculation results demonstrate that the introduction of diamine units can effectively improve the oxygen electrocatalysis. By tuning the catalytic centers, the CoTAPP-PATA-COF catalyzes the ORR and OER with high activity and stability.This work may shed light on developing catalytic COFs in energy storage and conversion systems.
　　Catalytic covalent organic frameworks with bifunctional roles in oxygen reduction reaction (from O2 to H2O) and oxygen evolution reaction (from H2O to O2) have been first demonstrated by integrating redox-active sites into the Co-porphyrin frameworks (Image by SARI)
　　

2022-10-19 more+

Researchers Propose a Novel Federated Learning-Based μXRD Image Screening Method

A research group at the Shanghai Advanced Research Institute, Chinese Academy of Sciences unveiled the solutions to improve the screening while protecting data privacy.The results of the physics law-informed federated learning (FL) based μXRD image screening method are published on IEEE TRANSACTIONS ON INDUSTRIAL INFORMATICS.

The X-ray microdiffraction (μXRD) in synchrotron radiation facilities are conducted for industrial minerals to identify their crystal impurities. Because of its unique advantages, it can be applied in many services such as client selection strategy, imbalanced data distribution, hybrid training, etc.
　　However, two major problems are hindering the development of accurate μXRD image screening. One is the lack of labeled industrial samples and the other is the privacy concerns of industrial users of μXRD services.
　　To address these problems, a research group led by Professor ZHU Yongxin at the Shanghai Advanced Research Institute, Chinese Academy of Sciences unveiled the solutions to improve the screening while protecting data privacy.
　　The results of the physics law-informed federated learning (FL) based μXRD image screening method are published on IEEE TRANSACTIONS ON INDUSTRIAL INFORMATICS.
　　Researchers firstly utilized the domain specific physical information to improve the federated learning accuracy. Then, with the consideration of the unbalanced data distributions in realistic world, they adopted a sampling scheme with novel client sampling algorithms. Thirdly, a hybrid training framework was proposed to deal with the unstable communication environment between FL clients and servers in federated learning.
　　The extensive experiments showed that the accuracy of machine learning models got improved by around 14% to 25% and the data features could be shared among different users or applications while keeping commercially confidential information.This novel system with federated learning features will be helpful in lifting the non-technical barriers on data sharing. It will help to relieve the stress on processing the increasing data volume in the facilities as well as lower the cost of the users of the facilities, thus enhancing the productivities of academic activities and industrial production.
　　Fig. 1. Labelled diffraction images from LN84 and LN498 dataset (Image by SARI)
　　Fig. 2. Improved accuracy in connection with various plug-in models (Image by SARI)
　　

2022-10-17 more+