Electrochemical reduction of CO2 into value‐added chemicals provides a promising approach to mitigate climate change caused by CO2 from excess consumption of fossil fuels. As the CO2 molecule is ...chemically inert and the reaction kinetics is sluggish, efficient electrocatalysts are thus highly required for promoting the conversion of CO2. With great efforts devoted to improving the catalytic performance, the development of electrocatalysts for CO2 reduction has gone from bulk metals with poor control to nanostructures with atomic precision. Nanostructured electrocatalysts with atomic precision are believed to be capable of combining the advantages of heterogeneous and homogenous catalysts. In this review, the recent advances in designing nanostructured electrocatalysts at the atomic level for boosting the catalytic performance toward CO2 reduction and revealing the structure–property relationship are summarized. The challenges and opportunities in the near future are also proposed for paving the development of electrocatalytic CO2 reduction.
The design of electrocatalysts for CO2 reduction has gone from bulk metals in the early stage to nanostructures with controlled compositions and structures with precision at the atomic level. This review highlights the recent advances in designing nanostructured electrocatalysts at the atomic level for boosting the catalytic performance toward CO2 reduction and revealing the structure–property relationship.
Sparse-view computed tomography (CT) holds great promise for speeding up data acquisition and reducing radiation dose in CT scans. Recent advances in reconstruction algorithms for sparse-view CT, ...such as iterative reconstruction algorithms, obtained high-quality image while requiring advanced computing power. Lately, deep learning (DL) has been widely used in various applications and has obtained many remarkable outcomes. In this paper, we propose a new method for sparse-view CT reconstruction based on the DL approach. The method can be divided into two steps. First, filter backprojection (FBP) was used to reconstruct the CT image from sparsely sampled sinogram. Then, the FBP results were fed to a DL neural network, which is a DenseNet and deconvolution-based network (DD-Net). The DD-Net combines the advantages of DenseNet and deconvolution and applies shortcut connections to concatenate DenseNet and deconvolution to accelerate the training speed of the network; all of those operations can greatly increase the depth of network while enhancing the expression ability of the network. After the training, the proposed DD-Net achieved a competitive performance relative to the state-of-the-art methods in terms of streaking artifacts removal and structure preservation. Compared with the other state-of-the-art reconstruction methods, the DD-Net method can increase the structure similarity by up to 18% and reduce the root mean square error by up to 42%. These results indicate that DD-Net has great potential for sparse-view CT image reconstruction.
The exploration of new porous hybrid materials is of great importance because of their unique properties and promising applications in separation of materials, catalysis, etc. Herein, for the first ...time, by integration of metal–organic frameworks (MOFs) and covalent organic frameworks (COFs), a new type of MOF@COF core–shell hybrid material, i.e., NH2‐MIL‐68@TPA‐COF, with high crystallinity and hierarchical pore structure, is synthesized. As a proof‐of‐concept application, the obtained NH2‐MIL‐68@TPA‐COF hybrid material is used as an effective visible‐light‐driven photocatalyst for the degradation of rhodamine B. The synthetic strategy in this study opens up a new avenue for the construction of other MOF–COF hybrid materials, which could have various promising applications.
By integration of metal–organic frameworks (MOFs) and covalent organic frameworks (COFs), a new type of MOF@COF core–shell hybrid material, i.e., NH2‐MIL‐68@TPA‐COF, with high crystallinity and hierarchical pore structure, is synthesized. The obtained hybrid material can be used as an effective visible‐light‐driven photocatalyst for the degradation of rhodamine B.
A facile surfactant‐assisted bottom‐up synthetic method to prepare a series of freestanding ultrathin 2D M‐TCPP (M = Zn, Cu, Cd or Co, TCPP = tetrakis(4‐carboxyphenyl)porphyrin) nanosheets with a ...thickness of sub‐10 nm is developed. As a proof‐of‐concept application, some of them are successfully used as new platforms for DNA detection. The Cu‐TCPP nanosheet‐based sensor shows excellent fluorescent sensing performance and is used for the simultaneous detection of multiple DNA targets.
The effect of rare earth cerium (Ce) on the localized corrosion behavior of the non-equiatomic Fe40Mn20Cr20Ni20 high-entropy alloys were investigated in 0.5 M H2SO4 solution. The corrosion resistance ...of the alloys increased with addition of Ce, which owing to the protectiveness and compactness of passive film was enhanced. The composition and shape of inclusions were modified by Ce, which resulted in the alteration of the localized corrosion behavior. A linear relationship between the doping density and thickness of the passive film was identified. The discussion based on the point defect model (PDM) was carried out and give a qualitative analysis.
The raw/processed data required to reproduce these findings cannot be shared at this time as the data also forms part of an ongoing study.
•Addition of Ce improved the corrosion resistance of the Fe40Mn20Cr20Ni20 HEAs.•Adding Ce changed the composition and shape of inclusions, resulting the alteration of the localized corrosion.•The compactness of the passive film was enhanced by addition of Ce.•A linear relationship between the doping density ND and thickness δ of the passive film was found.
Metal–organic frameworks (MOFs) have demonstrated great potentials in a variety of important applications. To enhance the inherent properties and endow materials with multifunctionality, the rational ...design and synthesis of MOFs with nanoscale porosity and hollow feature is highly desired and remains a great challenge. In this work, the formation of a series of well‐defined MOF (MOF‐5, FeII‐MOF‐5, FeIII‐MOF‐5) hollow nanocages by a facile solvothermal method, without any additional supporting template is reported. A surface‐energy‐driven mechanism may be responsible for the formation of hollow nanocages. The addition of pre‐synthesized poly(vinylpyrrolidone)‐ (PVP) capped noble‐metal nanoparticles into the synthetic system of MOF hollow nanocages yields the yolk–shell noble metal@MOF nanostructures. The present strategy to fabricate hollow and yolk–shell nanostructures is expected to open up exciting opportunities for developing a novel class of inorganic–organic hybrid functional nanomaterials.
Inorganic–organic hybrids: A series of well‐defined metal–organic frameworks and FeIII‐ICP hollow nanocages (see picture; ICP=infinite coordination polymer) were solvothermally prepared. A surface‐energy‐driven mechanism may be responsible for the formation of these hollow nanocages.
Inspired by the multiple functions of natural multienzyme systems, a new kind of hybrid nanosheet is designed and synthesized, i.e., ultrasmall Au nanoparticles (NPs) grown on 2D metalloporphyrinic ...metal‐organic framework (MOF) nanosheets. Since 2D metalloporphyrinic MOF nanosheets can act as the peroxidase mimics and Au NPs can serve as artificial glucose oxidase, the hybrid nanosheets are used to mimic the natural enzymes and catalyze the cascade reactions. Furthermore, the synthesized hybrid nanosheets are used to detect biomolecules, such as glucose. This study paves a new avenue to design nanomaterial‐based biomimetic catalysts with multiple complex functions.
Inspired by the multiple functions of natural multienzyme systems, hybrid nanosheets are designed and synthesized, i.e., ultrasmall Au nanoparticles are grown on 2D metalloporphyrinic metal‐organic framework nanosheets. Since nanosheets can act as the peroxidase mimics and Au nanoparticles can serve as artificial glucose oxidase, the hybrid nanosheets are used to mimic the natural enzymes and catalyze the cascade reactions.
Noise pollution has become a significant global problem in recent years. Unfortunately, conventional acoustic materials cannot offer substantial improvements in noise reduction. However, acoustic ...metamaterials are providing new solutions for controlling sound waves, and have huge potential for mitigating noise propagation in particular. Recently, owing to the rapid development of acoustic metamaterials, metamaterials for acoustic noise reduction have drawn the attention of researchers worldwide. These metamaterials are often both light and compact, and are excellent at reducing low‐frequency noise, which is difficult to control with conventional acoustic materials. Recent progress has illustrated that acoustic metamaterials effectively control sound waves, and optimizing their structure can enable functionality based on new physical phenomena. This review introduces the development of acoustic metamaterials, and summarizes the basic classification, underlying physical mechanism, application scenarios, and emerging research trends for both passive and active noise‐reduction metamaterials. Focusing on noise reduction, the shortcomings of current technologies are discussed, and future development trends are predicted. As our knowledge in this area continues to expand, it is expected that acoustic metamaterials will continue to improve and find more practical applications in emerging fields in the future.
This review introduces the development of acoustic metamaterials, the basic classification, the underlying mechanism, application scenario, and emerging trends for both passive and active noise‐reduction metamaterials. Acoustic metamaterials will continue to improve and the authors would likely believe these unusual metamaterials more practical in this emerging field in future.
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