Beijing University of Technology

About: Beijing University of Technology is a education organization based out in Beijing, Beijing, China. It is known for research contribution in the topics: Microstructure & Laser. The organization has 31929 authors who have published 31987 publications receiving 352112 citations. The organization is also known as: Běijīng Gōngyè Dàxué & Beijing Polytechnic University.

Carbon Nanotube Based Inverted Flexible Perovskite Solar Cells with All-Inorganic Charge Contacts

Abstract: Organolead halide perovskite solar cells (PSC) are arising as promising candidates for next-generation renewable energy conversion devices. Currently, inverted PSCs typically employ expensive organic semiconductor as electron transport material and thermally deposited metal as cathode (such as Ag, Au, or Al), which are incompatible with their large-scale production. Moreover, the use of metal cathode also limits the long-term device stability under normal operation conditions. Herein, a novel inverted PSC employs a SnO2-coated carbon nanotube (SnO2@CSCNT) film as cathode in both rigid and flexible substrates (substrate/NiO-perovskite/Al2O3-perovskite/SnO2@CSCNT-perovskite). Inverted PSCs with SnO2@CSCNT cathode exhibit considerable enhancement in photovoltaic performance in comparison with the devices without SnO2 coating owing to the significantly reduced charge recombination. As a result, a power conversion efficiency of 14.3% can be obtained on rigid substrates while the flexible ones achieve 10.5% efficiency. More importantly, SnO2@CSCNT-based inverted PSCs exhibit significantly improved stability compared to the standard inverted devices made with silver cathode, retaining over 88% of their original efficiencies after 550 h of full light soaking or thermal stress. The results indicate that SnO2@CSCNT is a promising cathode material for long-term device operation and pave the way toward realistic commercialization of flexible PSCs.

Terahertz in-line digital holography of human hepatocellular carcinoma tissue

Abstract: Terahertz waves provide a better contrast in imaging soft biomedical tissues than X-rays, and unlike X-rays, they cause no ionisation damage, making them a good option for biomedical imaging. Terahertz absorption imaging has conventionally been used for cancer diagnosis. However, the absorption properties of a cancerous sample are influenced by two opposing factors: an increase in absorption due to a higher degree of hydration and a decrease in absorption due to structural changes. It is therefore difficult to diagnose cancer from an absorption image. Phase imaging can thus be critical for diagnostics. We demonstrate imaging of the absorption and phase-shift distributions of 3.2 mm × 2.3 mm × 30-μm-thick human hepatocellular carcinoma tissue by continuous-wave terahertz digital in-line holography. The acquisition time of a few seconds for a single in-line hologram is much shorter than that of other terahertz diagnostic techniques, and future detectors will allow acquisition of meaningful holograms without sample dehydration. The resolution of the reconstructions was enhanced by sub-pixel shifting and extrapolation. Another advantage of this technique is its relaxed minimal sample size limitation. The fibrosis indicated in the phase distribution demonstrates the potential of terahertz holographic imaging to obtain a more objective, early diagnosis of cancer.

Atomic Mechanisms Governing the Elastic Limit and the Incipient Plasticity of Bending Si Nanowires

Abstract: Individual single-crystalline Si nanowires (NWs) were bent by forming loops or arcs with different radius. Positional-resolved atomic level strain distribution (PRALSD) along both of the radial and axial directions were calculated and mapped directly from the atomic-resolution strained high-resolution electron microscopy (HREM) images of the bent Si NWs. For the first time, the neutral-strain axis shifted from the compressive zone to the tensile region was directly demonstrated from the PRALSD along the radial direction. Bending-induced ripple-buckling of the bent Si NW was observed and a significant strain variation along the bending axial direction in the compressive region was revealed. The tensile surface atomic steps and the compressive buckling are the physical origin of the asymmetric tensile-compressive properties of postelastic instabilities and the incipient plasticity. Both of the tensile surface atomic-steps and the compressive buckling initiated versatile ductile plastic dislocation events.

Ruthenium-oxide-coated sodium vanadium fluorophosphate nanowires as high-power cathode materials for sodium-ion batteries.

Abstract: Sodium-ion batteries are a very promising alternative to lithium-ion batteries because of their reliance on an abundant supply of sodium salts, environmental benignity, and low cost. However, the low rate capability and poor long-term stability still hinder their practical application. A cathode material, formed of RuO2-coated Na3V2O2(PO4)2F nanowires, has a 50 nm diameter with the space group of I4/mmm. When used as a cathode material for Na-ion batteries, a reversible capacity of 120 mAh g−1 at 1 C and 95 mAh g−1 at 20 C can be achieved after 1000 charge–discharge cycles. The ultrahigh rate capability and enhanced cycling stability are comparable with high performance lithium cathodes. Combining first principles computational investigation with experimental observations, the excellent performance can be attributed to the uniform and highly conductive RuO2 coating and the preferred growth of the (002) plane in the Na3V2O2(PO4)2F nanowires.

Recovery of waste printed circuit boards through pyrometallurgical processing: A review

Abstract: In recent years, due to the large amount of waste electrical and electronic equipment. Researchers need to search for a method to solve the harmless disposal of waste printed circuit boards (WPCBs) as soon as possible. Considering that WPCBs contain metals and polymeric materials, they have been considered to be an important urban mineral resource. The recycling of WPCBs has been widely studied. Published research shows that pyrometallurgical processing is an economic and effective method to achieve WPCBs harmless recycling and resource utilization. This paper summarizes and analyzes the research results of pyrometallurgical processing for the recycling of WPCBs in recent years, and recovery processes such as incineration, pyrolysis, plasma and molten salt are discussed. Some proposals against the existing problems during pyrometallurgical processing process were presented. We hope that this paper can provide some certain assistances to policy makers, other researchers and the practitioners in the WPCB recycling enterprise.