Many studies have been published in recent years focusing on the recovery of rare earth elements (REEs) from coal-related materials, including coal, coal refuse, coal mine drainage, and coal ...combustion byproducts particularly fly ash. The scientific basis and technology development have been supported by coal geologists and extractive metallurgists, and through these efforts, the concept has progressed from feasibility assessment to pilot-scale production over the last five years. Physical beneficiation, acid leaching, ion-exchange leaching, bio-leaching, thermal treatment, alkali treatment, solvent extraction, and other recovery technologies have been evaluated with varying degrees of success depending on the feedstock properties. In general, physical beneficiation can be a suitable low-cost option for preliminary upgrading; however, most studies showed exceedingly low recovery values unless ultrafine grinding was first performed. This finding is largely attributed to the combination of small RE-bearing mineral particle size and complex REE mineralogy in coal-based resources. Alternatively, direct chemical extraction by acid was able to produce moderate recovery values, and the inclusion of leaching additives, alkaline pretreatment, and/or thermal pretreatment considerably improved the process performance. The studies reviewed in this article revealed two major pilot plants where these processes have been successfully deployed along with suitable solution purification technologies to continuously produce high-grade mixed rare earth products (as high as +95%) from coal-based resources. This article presents a systematic review of the recovery methods, testing outcomes, and separation mechanisms that are involved in REE extraction from coal-related materials. The most recent findings regarding the modes of occurrence of REEs in coal-related materials are also included.
Thin TiO2 films are demonstrated to be an excellent electron‐selective contact for crystalline silicon solar cells. An efficiency of 21.6% is achieved for crystalline silicon solar cells featuring a ...full‐area TiO2‐based electron‐selective contact.
Photovoltaic (PV) technology offers an economic and sustainable solution to the challenge of increasing energy demand in times of global warming. The world PV market is currently dominated by the ...homo-junction crystalline silicon (c-Si) PV technology based on high temperature diffused p-n junctions, featuring a low power conversion efficiency (PCE). Recent years have seen the successful development of Si heterojunction technologies, boosting the PCE of c-Si solar cells over 26%. This article reviews the development status of high-efficiency c-Si heterojunction solar cells, from the materials to devices, mainly including hydrogenated amorphous silicon (a-Si:H) based silicon heterojunction technology, polycrystalline silicon (poly-Si) based carrier selective passivating contact technology, metal compounds and organic materials based dopant-free passivating contact technology. The application of silicon heterojunction solar cells for ultra-high efficiency perovskite/c-Si and III-V/c-Si tandem devices is also reviewed. In the last, the perspective, challenge and potential solutions of silicon heterojunction solar cells, as well as the tandem solar cells are discussed.
Multi-atlas segmentation is widely accepted as an essential image segmentation approach. Through leveraging on the information from the atlases instead of utilizing the model-based segmentation ...techniques, the multi-atlas segmentation could significantly enhance the accuracy of segmentation. However, label fusion, which plays an important role for multi-atlas segmentation still remains the primary challenge. Bearing this in mind, a deep learning-based approach is presented through integrating feature extraction and label fusion. The proposed deep learning architecture consists of two independent channels composing of continuous convolutional layers. To evaluate the performance our approach, we conducted comparison experiments between state-of-the-art techniques and the proposed approach on publicly available datasets. Experimental results demonstrate that the accuracy of the proposed approach outperforms state-of-the-art techniques both in efficiency and effectiveness.
The performance of state‐of‐the‐art perovskite solar cells is currently limited by defect‐induced recombination at interfaces between the perovskite and the electron and hole transport layers. These ...defects, most likely undercoordinated Pb and halide ions, must either be removed or passivated if cell efficiencies are to approach their theoretical limit. In this work, a universal double‐side polymer passivation approach is introduced using ultrathin poly(methyl methacrylate) (PMMA) films. Very high‐efficiency (≈20.8%) perovskite cells with some of the highest open circuit voltages (1.22 V) reported for the same 1.6 eV bandgap are demonstrated. Photoluminescence imaging and transient spectroscopic measurements confirm a significant reduction in nonradiative recombination in the passivated cells, consistent with the voltage increase. Analysis of the molecular interactions between perovskite and PMMA reveals that the carbonyl (CO) groups on the PMMA are responsible for the excellent passivation via Lewis‐base electronic passivation of Pb2+ ions. This work provides new insights and a compelling explanation of how PMMA passivation works, and suggests future directions for developing improved passivation layers.
Interface recombination is a dominant loss mechanism in perovskite solar cells. Double‐side passivation of perovskite solar cells using ultrathin films of poly(methyl methacrylate) (PMMA) can boost open circuit voltages up to 1.22 V. This results from the carbonyl (CO) group of the Lewis‐base polymer PMMA, which effectively passivates under‐coordinated Pb atoms (Pb2+) at the perovskite/transport layer interfaces.
Exposure to ultraviolet (UV) light is known to cause skin aging, skin damage, cancer, and eye diseases, as well as polymer material aging. Therefore, significant attention has been devoted to the ...research and development of UV absorbers. Considering the robust hydrogen bonding and conjugated structure present in nitrogen-containing polycyclic compounds, these compounds have been selected as potential candidates for exploring ultraviolet absorption properties. After structural optimization and the simulation of ultraviolet absorption spectra, four tris-1,2,4-triazolo-1,3,5-triazine (TTTs) derivatives, namely TTTB, TTTD, TTTJ, and TTTL, were selected as the preferred compounds and synthesized. The structure of the compound was determined using various analytical techniques, including FTIR,
HNMR,
CNMR, HRMS, and XRD. Subsequently, composite films of polyvinyl chloride (PVC) and TTTs were produced using a simple solvent casting technique. The PVC films were subjected to UV age testing by exposing them to an ultraviolet aging chamber. The age-resistant performance of the fabricated films was evaluated using an ultraviolet spectrophotometer and Fourier infrared spectrum instrument. The findings suggest that TTTs exhibit a noteworthy capacity for absorbing ultraviolet radiation. The TTTL compound exhibits a superior UV absorption performance compared to commercially available UV absorbers such as UV-0 and UV-327 in the market.
It is an arduous and meaningful challenge to design and develop new energetic materials with lower sensitivity and higher energy. How to skillfully combine the characteristics of low sensitivity and ...high energy is the key problem in designing new insensitive high-energy materials. Taking a triazole ring as a framework, a strategy of
-oxide derivatives containing isomerized nitro and amino groups was proposed to answer this question. Based on this strategy, some 1,2,4-triazole
-oxide derivatives (
s) were designed and explored. The electronic structure calculation showed that the stable existence of these triazole derivatives was due to the intramolecular hydrogen bond and other interactions. The impact sensitivity and the dissociation enthalpy of trigger bonds directly indicated that some compounds could exist stably. The crystal densities of all
s were larger than 1.80 g/cm
, which met the requirement of high-energetic materials for crystal density. Some
s (9748 m/s for
, 9841 m/s for
, 9818 m/s for
, 9906 m/s for
, and 9592 m/s for
) were potential high detonation velocity energy materials. These study results not only indicate that the
s have relatively stable properties and excellent detonation properties but also prove that the strategy of nitro amino position isomerization coupled with
-oxide is an effective means to develop new energetic materials.
The crystalline silicon (c-Si) based technologies occupy 95% market share in the global photovoltaic (PV) production capacity. The conversion efficiency of silicon heterojunction (SHJ) solar cell in ...mass production has gone beyond 23%. The most pressing challenge hindering the industrial scale expansion of SHJ solar cell currently is the relatively high production cost as compared to the PERC (passivated emitter and rear cell) product. The low temperature silver paste utilized in the SHJ cell process accounts significantly for about 30% of the total processing cost due to its large consumption. Copper plating is of great current interest to silicon heterojunction application, which has a high potential to cut down the cost and improve cell efficiency by the remarkably reduced shading loss, increased electrode conduction and fill factor. However, there are still some critical issues need to be systematically optimized and proven for mass production. Selectively-deposited seed layer and stripping-free plating resist are the key factors to simplify the plating process. This paper gives a detailed look into the development of copper metallization for SHJ solar cell. Plating process involving seed layer formation and patterning methods are explicated. The process simplification and reliability are discussed aiming at its employment in industrial production.
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