Researchers Develop an Adaptive NOMA-based Spectrum Sensing for Next Generation of IoT Networks

An international collaborative research team led by the Shanghai Advanced Research Institute (SARI) of the Chinese Academy of Sciences proposed an innovative NOMA-based spectrum sensing algorithm for uplink IoT networks, which improves the efficiency of targeting frequency usage in multi-user systems.

As the Internet of Things (IoT) network continues to expand, the challenge of managing limited spectrum resources intensifies. Studies have shown that both non-orthogonal multiple access (NOMA) and spectrum sensing have the potential to increase spectrum utilization.
　　While NOMA and spectrum sensing can ease the spectrum shortage, the combination of them does not reach the upper bound of spectrum utilization due to certain reasons. Also, it faces the challenge of detecting the signal states when multiple users superpose.
　　To address these problems, a collaborative research team led by Prof. XU Tianhong and HU Honglin from the Shanghai Advanced Research Institute (SARI) of the Chinese Academy of Sciences (CAS), in partnership with VTT Technical Research Centre of Finland, the University of Electro-Communications in Japan, and Shanghai University, proposed an innovative NOMA-based spectrum sensing algorithm for uplink IoT networks, which improves the efficiency of targeting frequency usage in multi-user systems.
　　The research results were published in the latest issue of IEEE Transactions on Cognitive Communications and Networking.
　　Focusing on inter-system orthogonal/non-orthogonal aliasing coexistence scenarios, researchers propose an adaptive spectrum sensing technology for the multi-user uplink NOMA system, which harmonizes the advancements in both static and dynamic spectrum efficiency.
　　Moreover, researchers have derived the closed-form expressions among the number of primary users, user transmission willingness, the power ratio and the false-alarm probability in various sensing processes. These formulas have been validated through numerous simulations.
　　Furthermore, an adaptive NOMA-based sensing algorithm is designed and showcases an impressive 38.20% improvement in system throughput, compared with state-of-the-art techniques.
　　This research holds the promise of transforming the landscape of spectrum utilization in the emerging IoT era.
　　Schematic diagram of inter-system orthogonal/non-orthogonal aliasing coexistence IoT sensing scenarios (Image by SARI)
　　Contact: XU Tianheng
　　Shanghai Advanced Research Institute
　　Email: xuth@sari.ac.cn
　　

Researchers Design a Novel Hollow-Fiber Cu Penetration Electrode for Efficient CO2 Electroreduction

A research team from the Shanghai Advanced Research Institute (SARI) of the Chinese Academy of Sciences designed a Cu hollow fiber penetration electrode to electroreduce CO2 in strong acid with effective inhibition of hydrogen evolution reaction (HER). The results were published in Energy & Environmental Science.

Electrochemical conversion of CO2 into value-added chemical fuels driven by renewable electrical energy has twofold roles in reducing net CO2 emission and in addressing energy consumption.Although considerable progress has been made in CO2 electroreduction, carbonate formation can cause serious CO2 loss. CO2 conversion in acidic electrolyte is an attractive way to overcome CO2 loss, however, the selective reduction remains a challenge.Motivated by this challenge, a research team from the Shanghai Advanced Research Institute (SARI) of the Chinese Academy of Sciences designed a Cu hollow fiber penetration electrode to electroreduce CO2 in strong acid with effective inhibition of hydrogen evolution reaction (HER).The results were published in Energy & Environmental Science on December 13, 2023. By virtue of the unique penetration effect induced by Cu hollow fiber, abundant CO2 molecules were supplied to Cu active sites. Cu surface possessed enough high CO2 coverage, which suppressed HER and facilitated CO2 reduction to C2+ products.Thus, a CO2 single-pass conversion rate exceeding 51% with a C2+ Faradaic efficiency of 73.4% and partial current density of 2.2 A cm-2 was achieved in acidic solution (pH = 0.71). The performance of the Cu penetration electrode approximated to or even outperformed those of the state-of-the-art Cu base catalysts.This work represents an encouraging headway in the design and development of new electrode configurations to realize CO2 electroreduction to high-value C2+ chemicals with scalable applications.
　　Schematic diagram and electrocatalytic performance comparison of CO2 reduction in acidic media over Cu hollow fiber penetration electrode (image by SARI)
　　

Researchers Develop COFs Adsorbent for Efficient Gold Recovery

Most reported COFs have been focused on constructing hydrogen bond interactions inside frameworks to improve the adsorption capacity and gold selectivity, while the effects of intrinsic frameworks on gold capture are unproved.Recently, a research team at the Shanghai Advanced Research Institute (SARI) developed a skeleton engineering of COFs for high-efficiency absorbs towards gold capture.The results were published in Angew. Chem. Int. Ed.

　　Adsorbents with high capture efficiency and capacity are crucial in precious metal resource recovery. Covalent organic frameworks (COFs), a class of crystalline porous organic materials, are regarded as ideal templates for ions adsorption due to their elaborate designability and modifiability.
　　However, most reported COFs have been focused on constructing hydrogen bond interactions inside frameworks to improve the adsorption capacity and gold selectivity, while the effects of intrinsic frameworks on gold capture are unproved.
　　Recently, a research team led by Prof. ZENG Gaofeng and Associate Prof. XU Qing at the Shanghai Advanced Research Institute (SARI), collaborated with Prof. HAN Baohang and Associate Prof. DING Xuesong at Nanoscience National Center for Nanoscience and Technology, developed a skeleton engineering of COFs for high-efficiency absorbs towards gold capture.
　　The results were published in Angew. Chem. Int. Ed.
　　Researchers first construct three electron-neutral COFs with diarylamine derivatives. Then, they use the Menshutkin reaction to synthesis ionic COFs containing ionic skeleton which can enhance the column force between Au ions and frameworks.
　　The adsorption performance is further improved by introducing an ionized skeleton. The ionic COFs exhibit the adsorption capacity of 1834 mg g-1 and reached 90% of the maximum adsorption within 10 mins with good cyclic stability.
　　The theoretical calculation shows that the transition of binding site from imine bond to ionic nitrogen after the post modification, which helps to enhance coulomb force with gold ions, further improving the adsorption kinetics.This work provides inspirations of designing COFs-based molecular/ion trapping agents.  
　　Skeleton engineering was adopted to form COFs with diarylamine derivatives and ionized skeletons (Imaged by SARI)
　　Contact: ZENG Gaofeng
　　Shanghai Advanced Research Institute
　　Email:zenggf@sari.ac.cn
　　

Researchers Propose a Novel Approach for Dimensional Engineering of Covalent Organic Frameworks Derived Carbons

A research group led by Prof. ZENG Gaofeng and XU Qing at Shanghai Advanced Research Institute (SARI) of the Chinese Academy of Sciences, in collaboration with Prof. HE Yue at Shanghai Jiao Tong University, used template-synthesis strategy to first put forward COFs derived carbons in different dimensions to catalyze CO2RR. The results were published in SusMat on Nov. 10.

Covalent organic frameworks (COFs) are a special class of materials composed of interconnected organic building blocks held together by strong chemical bonds. Featured with evenly distributed atoms and abundant internal empty space, COFs can be utilized as the starting point for developing functional carbon-based materials.When COFs are subjected to high temperatures, they lose their two-dimensional flat shape and become a three-dimensional structure. In order to obtain the carbon dioxide reduction (CO2RR) catalysts with large porosity, high conductivity and abundance of edge sites for doped heteroatoms, the structure control of COF derived carbon is of vital importance but is still underexplored.Recently, a research group led by Prof. ZENG Gaofeng and XU Qing at Shanghai Advanced Research Institute (SARI) of the Chinese Academy of Sciences, in collaboration with Prof. HE Yue at Shanghai Jiao Tong University, used template-synthesis strategy to first put forward COFs derived carbons in different dimensions to catalyze CO2RR.The results were published in SusMat on Nov. 10.Researchers used different methods to create 1D — 3D carbon materials derived from COFs. For the 1D carbon, a layer of COFs was deposited on carbon nanotubes (CNTs), while for the 2D carbon, COFs were deposited on graphene (Gr). As a comparison, they also directly carbonized the COF precursor to create 3D carbon. The COF precursor used in the experiments was TP-BPY-COF, which was synthesized from specific chemicals using solvothermal methods.Synthesis of 1D — 3D carbon materials derived from COFs (Image by SARI)
　　EXAFS spectra showed that the resulting COF-derived carbon materials contained plenty of nitrogen (N) sites, which acted as catalytic centers, particularly in the form of CoN5. Among the various catalysts tested, the 1D COF-based catalyst exhibited exceptional performance due to its strong affinity for CO2, a higher number of defective sites, and superior electronic conductivity. These qualities resulted in greater CO2RR activity and selectivity towards the desired product (CO), compared to the 2D and 3D catalysts.The results not only present the significance of tailoring the structure of COF-derived carbons to enhance their effectiveness as catalysts in CO2 reduction reactions, but also provide a new perspective to develop efficient COF-based catalysts. By employing COF-derived carbon materials as catalysts for CO2 electroreduction, CO2 can be potentially converted into valuable chemical compounds or even renewable fuels.
　　  

Novel Approach for Single-Shot Characterization of Ultrashort Free-Electron Laser Pulses

the free electron laser team led by Prof. FENG Chao at the Shanghai Advanced Research Institute (SARI) of the Chinese Academy of Sciences (CAS) proposed and validated a novel approach for single-shot characterization of ultrashort free electron laser pulses based on self-referenced spectral interferometry. The research results were published in Physical Review Letters.

Attosecond light pulses can be used to observe and manipulate the electronic motion within atoms and molecules, thus helping scientists to gain a deeper understanding of chemical reactions, electronic structures, and molecular dynamics. The complete spectrotemporal characterization of attosecond X-ray free-electron lasers is of great significance to ultrafast scientific experiments. However, the high-precision single-shot characterization of these pulses has been a key bottleneck in the application of attosecond X-ray free-electron lasers.To address this issue, the free electron laser team led by Prof. FENG Chao at the Shanghai Advanced Research Institute (SARI) of the Chinese Academy of Sciences (CAS) proposed and validated a novel approach for single-shot characterization of ultrashort free electron laser pulses based on self-referenced spectral interferometry.The research results were published in Physical Review Letters.The team innovatively proposed a method of using the frequency-pulling effect as a way to induce the spectral shear. Through this method, both the ultrafast radiation pulse and the reference pulse will be generated from the same electron beam, enabling self-referenced spectral interferometry of the radiation pulse.With the help of the parameters of the Shanghai soft X-ray free-electron laser facility, researchers demonstrated that this method can accurately reconstruct the complete spectrotemporal information of attosecond X-ray pulses, and the reconstruction error rate was less than 6 percent.Compared to traditional ultrafast pulse characterization methods in free-electron laser facilities, this method has several advantages. It involves only simple equipment, but can yield high diagnostic efficiency (real-time, single-shot), with simultaneous acquisition of complete spectrotemporal information, and higher diagnostic precision for shorter radiation pulses. These advantages provide a novel diagnostic approach for the optimization and fine-tuning of ultrafast X-ray free-electron lasers and future attosecond scientific experiments based on X-ray free-electron lasers.This study can provide a fresh approach to address the challenge of high-precision real-time diagnostics for attosecond free electron laser pulses. Schematic layout of the proposed method and spectrotemporal reconstructions of attosecond X-ray free-electron laser pulses (Image by SARI) 

Novel discovery on Al(III) Doping of ε-Fe2O3 in the Ancient High-iron Black-brown Glaze

Based on siliceous clay and calcareous wood ash, the world’s first high-fired glazes were made in China, the technology of which was at its zenith by the Song Dynasty (960-1279) including blackware glazes with single-phase, micron-scale ε-Fe2O3 films identified on their surfaces. However, modern synthetic methods are still difficult to synthesize and reproduce the effects on a larger scale without other iron oxide polymorph impurities.To understand the effect, a research team made up of Prof. WEI Xiangjun from Shanghai Advanced Research Institute (SARI) of the Chinese Academy of Sciences, Dr. LEI Yong and Dr. GUAN Ming from the Palace Museum, and Prof. MA Ding and Dr. GUO Yu from Peking University developed a novel strategy combining nanomaterial science method and theoretical calculation to investigate the hare’s fur glaze of Song Dynasty Jian wares.The research results were published in Journal of the American Ceramic Society entitled " Uncovering the Mystery of Al(III) Doping of ε-Fe2O3 in the Ancient High-iron Black-brown Glaze”.A major breakthrough has been achieved in this work through proving that high-alumina clay introduced Al into the glazes, which doped Al into ε-Fe2O3 lattices and thus stabilized the metastable polymorph based on XRD refinement, TEM-EDS, and theoretical calculation.Moreover, with SR-based XAS, M？ssbauer spectroscopy and SEM-EBSD, uniform-sized, high-yield and oriented ε-Fe2O3 films and ionic Fe2+ were discovered on a silver hare’s fur glaze, an effect managed by the ancient potters through a subtle control of atmosphere and firing environment.This work deepens the understanding of high-alumina, high-calcia, high-fired glazes and their subtle firing manipulation technology, which in turn should help advance new approaches to materials synthesis.
　　The manipulation of firing process of silver and gold hare’s fur glazes. (Image by SARI)