Researchers Propose Bit-Cigma: A Zero-Error, Sparsity-Aware Matrix Multiplication Accelerator for AI

A research group from Shanghai Advanced Research Institute of Chinese Academy of Sciences has unveiled Bit-Cigma, a revolutionary generic matric multiplication accelerator hardware architecture that optimizes bit-sparsity, ensures zero-error accuracy, and remodels floating-point computations. The results were published in Feb 2025 in IEEE Transactions on Computers.

Recently, a research group led by Prof. ZHU Yongxin from Shanghai Advanced Research Institute of Chinese Academy of Sciences has unveiled Bit-Cigma, a revolutionary generic matric multiplication accelerator hardware architecture that optimizes bit-sparsity, ensures zero-error accuracy, and remodels floating-point computations.The results were published in Feb 2025 in IEEE Transactions on Computers, a top-tier journal in the field of computer architecture.Matrix multiplication underpins artificial intelligence (AI) and scientific computing, driving processes such as neural network training and complex simulations. These fields demand efficient computing power capable of both floating-point (FP) and quantized integer (QINT) operations with exceptional performance and accuracy.However, the development of efficient matrix multiplication accelerators faces two persistent challenges. First, the inherent bit-level redundancy in binary data representation wastes computational resources and limits computational efficiency. Second, the floating-point exponent matching relies on slow, resource-heavy methods that bottleneck throughput and compromise accuracy.Bit-Cigma is a scalable, bit-level sparsity-aware architecture designed to handle various datatypes while delivering superior performance, accuracy, and efficiency for matrix multiplications across diverse tasks. The researchers proposed the Compact Canonical Signed Digit (CCSD) encoding technique, a streamlined on-chip method that slashes redundant computations by maximizing bit-level sparsity, all at half the cost of traditional approaches. For large matrices, the team devised a segmented approach that splits data into manageable blocks and aligns floating-point exponents dynamically. This ensures pinpoint accuracy and boosts processing speed and throughput without taxing hardware resources.Extensive experiments demonstrate that Bit-Cigma, utilizing CCSD, achieves a performance boost of 3 to 4 times and improves efficiency by over 10 times compared to state-of-the-art FP and QINT accelerators. Additionally, Bit-Cigma achieves zero computational error, a feat not matched by other accelerators.The Bit-Cigma architecture and the CCSD technique pave the way for more efficient, high-performance solutions for generic matrix multiplication. These advancements promise to support a range of applications and set the foundation for future hardware-centric high-performance systems.

Researchers Developed a Novel Ni Hollow Fiber Electrode for High-efficiency CO2 Electroreduction

In a study published in The Innovation​, a research team from Shanghai Advanced Research Institute of the Chinese Academy of Sciences constructed a hierarchical SnO2(101)@Ni composite hollow-fiber penetration electrode (HPE), which helped to realize high-efficiency CO2 electroreduction to formate in neutral electrolyte at ampere-level.

In a study published in The Innovation, Prof. WEI Wei, Prof. CHEN Wei and Prof. SONG Yanfang from Shanghai Advanced Research Institute of the Chinese Academy of Sciences constructed a hierarchical SnO2(101)@Ni composite hollow-fiber penetration electrode (HPE), which helped to realize high-efficiency CO2 electroreduction to formate in neutral electrolyte at ampere-level.The electrochemical CO2 reduction reaction (eCO2RR), powered by renewable energy, is a promising method for converting CO2 into value-added products, thereby enabling sustainable carbon-neutral cycles. However, the practical implementation of eCO2RR technology is challenged by limitations in activity, selectivity, and stability.To simultaneously achieve high formate Faradaic efficiency, high current density, and long-term stability, researchers constructed facet-oriented SnO2 nanoflowers arrayed on the exterior of three-dimensional nickel hollow fibers by a facile hydrothermal method.This electrode demonstrates exceptional electrocatalytic performance for converting CO2 to formate. A formate selectivity of 94% and stability of 300 h with a current density of 1.3 A cm-2 at −1.1 V (vs. RHE) are attained under ambient conditions. Notably, an extremely high CO2 single-pass conversion rate of 85% is achieved, outperforming prominent catalysts reported in electrocatalysis.The synergetic combination of the unique nanostructures and their advanced spatial configuration is proposed to be responsible for the facet-oriented SnO2 with a hierarchical structure, providing fully exposed active sites and facilitating mass and charge transfers. Enhanced mass transfer in the hollow fiber electrode verified by electrochemical measurements and well-retained Sn4+ species confirmed by in situ spectroscopy synergistically boost the high CO2 conversion activity. In situ spectroscopy and theoretical calculation results demonstrate that the SnO2(101) facet favors *OCHO intermediate formation and *HCOOH desorption, leading to high formate selectivity.This study provides a straightforward approach to the precise fabrication of composite hollow fiber electrodes, enabling highly efficient electrocatalytic reactions with gas molecules.Schematic diagram of electroreduction of CO2 to formate over SnO2@Ni hollow fiber penetration electrode (Image by SARI)

Researchers Propose a Novel Hollow Fiber Electrode for Efficient Electrocatalytic Conversion of CO2

In a study published in Angewandte Chemie, Prof. WEI Wei, Prof. CHEN Wei and Prof. SONG Yanfang from Shanghai Advanced Research Institute of the Chinese Academy of Sciences constructed a hierarchical Cl-SnO2@Ni HF Composite hollow-fiber penetration electrode (HPE), which helped to realize high-efficiency CO2 electroreduction to formate in neutral electrolyte at ampere-level.Renewable energy-driven electrochemical CO2 reduction has emerged as a promising technology for a sustainable future. However, achieving efficient production of storable liquid fuels at ampere-level current densities remains a significant hurdle in the large-scale implementation of CO2 electroreduction.To further improve the selectivity and conversion rate of formate at ampere-level current density, researchers constructed chlorine-doped SnO2 nanoflowers arrayed on the exterior of three-dimensional nickel hollow fibers by a facile hydrothermal method.This electrode demonstrates exceptional electrocatalytic performance for converting CO2 to formate, achieving a remarkable formate selectivity of 99% and a CO2 single-pass conversion rate of 93% at 2 A cm-2. Furthermore, it exhibits excellent stability, maintaining a formate selectivity of above 94% for 520 h at a current density of 3 A cm-2.Experimental results combined with theoretical calculations confirm that the enhanced mass transfer facilitated by the hollow fiber penetration effect, coupled with the well-retained Sn4+ species and Sn-Cl bonds, synergistically elevates the activity of CO2 conversion. The incorporation of chlorine into SnO2 enhances electron transport and CO2 adsorption, substantially lowering the reaction energy barrier for the crucial intermediate *OCHO formation, and boosting the formate production.This work provides valuable insights into the rational design of high-performance catalytic electrodes for CO2 electroreduction.Schematic diagram of electroreduction of CO2 to formate over Cl-SnO2@Ni HF penetration electrode. (Image by SARI)

​Researchers Propose Multifunctional Buffer Layer Engineering for Efficient and Stable Wide-Bandgap Perovskite

In a study published in Angewandte Chemie, a research team from Shanghai Advanced Research Institute (SARI) of the Chinese Academy of Sciences, collaborated with City University of Hong Kong reported a facile and effective strategy for precisely modulating the perovskite by incorporating AlOx deposited by atomic layer deposition (ALD) on the top interface.

Perovskite solar cells (PSCs) have become a revolutionary photovoltaic technology because of their high performance, low cost, and easy fabrication of large-scale flexible devices. However, the solution processing and the low formation energy of perovskites lead to numerous defects formed at both the bulk and interfaces of the perovskite layer, which ultimately results in a substantial deficit in the open-circuit voltage (VOC).In a study published in Angewandte Chemie, Prof. LU Linfeng from Shanghai Advanced Research Institute (SARI) of the Chinese Academy of Sciences, collaborated with Prof. Alex K.-Y. Jen at City University of Hong Kong reported a facile and effective strategy for precisely modulating the perovskite by incorporating AlOx deposited by atomic layer deposition (ALD) on the top interface.Researchers found that Al3+ ions not only infiltrated in the perovskite layer but also interacted with halide ions. The modification contributed to realizing better-matched energy levels, suppressed ion migration and minimized interfacial carrier losses simultaneously.Additionally, the self-encapsulation effect of this dense interlayer could inhibit volatile ion overflow at high temperatures and improve light and thermal stability.Consequently, the ALD-AlOx modification could significantly improve the PCE of wide-bandgap PSCs from 19.32% to 21.80%. More importantly, a monolithic perovskite-silicon tandem solar cells using AlOx-modified perovskite achieved a PCE of 28.50% with good stability.The resulting 1.55-eV PSC and module also achieved a PCE of 25.08% (0.04 cm2) and 21.01% (aperture area of 15.5 cm2), respectively, proving the universality of the strategy. The study provides an effective way for efficient and stable wide-band gap perovskite and perovskite-silicon TSCs and shed light on large-area inverted PSCs.Figure:The schematic diagram of incorporating AlOx deposited on perovskite surface(image by SARI)<!--!doctype-->

Researchers Developed a Spatial-coupling Strategy to Facilitate Efficient Propylene Oxide Production

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 a spatial-coupling strategy over RuO2/Ti hollow-fiber penetration electrode (HPE) to facilitate efficient PO production, significantly improving PER performance to ampere level. The results were published in Angew. Chem. Int. Ed. ​on Aug 7th, 2024.

The electrochemical propylene epoxidation reaction (PER) provides a promising route for ecofriendly propylene oxide (PO) production, instantly generating active halogen/oxygen species to alleviate chloride contamination inherent in traditional PER.However, the complex processes and unsatisfactory PO yield for current electrochemical PER falls short of meeting industrial application requirements.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 a spatial-coupling strategy over RuO2/Ti hollow-fiber penetration electrode (HPE) to facilitate efficient PO production, significantly improving PER performance to ampere level.The results were published in Angew. Chem. Int. Ed. on Aug 7th, 2024.The unique penetration effect of HPE forces gaseous propylene dispersion and penetration through the porous HPE wall, leading to greatly boosted PER kinetics from oriented mass transfer and enhanced interface reactions.Furthermore, the spatial coupling of anodic CP intermediate with cathodic OH− within a membraneless single-chamber reactor establishes a subtle reaction sequence, simplifying the PO production process to one step.The synergetic combination of the penetration and spatial coupling effects, greatly boosts ampere-level PO production with high specificity, achieving significantly improved PER performance up to ampere level, with PO faradaic efficiency of ≥80% and a maximum PO current density of 859 mA cm−2.This work exhibits significant potential for economically viable PER applications.Figure. Schematic illustration of spatial-coupled ampere-level electrochemical propylene epoxidation over RuO2/Ti HPE. (image by SARI)

​Researchers Propose a Novel Ag Electrode for Efficient Electrocatalytic Conversion of CO2

In a study published in Nature Communications, Prof. WEI Wei and Prof. CHEN Wei from Shanghai Advanced Research Institute of the Chinese Academy of Sciences constructed a hierarchical Ag hollow-fiber penetration electrode(HPE), which helped to realize high-efficiency CO2 electroreduction in strongly acidic electrolytes at ampere-level current density.

The electrochemical conversion of CO2 driven by renewable electricity can produce value-added chemicals and feedstocks while mitigating CO2 emissions. Synthesis of valuable chemicals from CO2 electroreduction in acidic media can overcome carbonation, however, how to suppress the hydrogen evolution reaction in such proton-rich environments is very challenging.In a study published in Nature Communications, Prof. WEI Wei and Prof. CHEN Wei from Shanghai Advanced Research Institute of the Chinese Academy of Sciences constructed a hierarchical Ag hollow-fiber penetration electrode(HPE), which helped to realize high-efficiency CO2 electroreduction in strongly acidic electrolytes at ampere-level current density.Previous studies by the research team have indicated that the HPE with a compact structure has shown promising potential for high-rate and efficient CO2 reduction due to enhanced mass transport, thus realizing the generation of CO, formate and C2+ products under ampere-level current density.In order to further explore the efficient working mechanism of HPE in acid system, an Ag2CO3-derived hierarchical micro/nanostructured silver HPE (CD-Ag HPE) was developed to investigate the effects of catalyst microenvironments on CO2 electrolysis performance in an acidic medium (pH =1).Experiments and theoretical studies demonstrated that the the presence of K+ in the acidic electrolyte controlled the onset of the electrocatalytic CO2 reduction reaction (CO2RR), and that a moderate concentration of H+ effectively prevented the carbonation of CO2 and CO2RR active sites due to the precipitation of (bi)carbonate, ensuring sufficient CO2 and CO2RR active sites at the catalyst surface for high-efficiency CO2RR at ampere-level current density.By optimizing the K+ and H+ concentration and CO2 flow rate in a strong acidic electrolyte, a high CO faradaic efficiency of 95% at 4.5 A/cm2 and a 200 h of stability testing at 2 A/cm2 were achieved.In addition, by limiting the availability of input CO2, the CO2 single-pass carbon efficiency for CO2RR reached 87% at a high j of 2 A/cm2, demonstrating remarkable CO2 conversion capability.This study paves the way for high-efficiency CO2 conversion in strong acid by modulating catalyst microenvironments, which has great potential for practical application.Figure. Schematic of Ag hollow fiber penetration electrode for boosting CO2 electroreduction to CO in a strongly acidic electrolyte (Image by SARI)