As one of the most critical approaches to resolve the energy crisis and environmental concerns, carbon dioxide (CO2) photoreduction into value‐added chemicals and solar fuels (for example, CO, HCOOH, ...CH3OH, CH4) has attracted more and more attention. In nature, photosynthetic organisms effectively convert CO2 and H2O to carbohydrates and oxygen (O2) using sunlight, which has inspired the development of low‐cost, stable, and effective artificial photocatalysts for CO2 photoreduction. Due to their low cost, facile synthesis, excellent light harvesting, multiple exciton generation, feasible charge‐carrier regulation, and abundant surface sites, semiconductor quantum dots (QDs) have recently been identified as one of the most promising materials for establishing highly efficient artificial photosystems. Recent advances in CO2 photoreduction using semiconductor QDs are highlighted. First, the unique photophysical and structural properties of semiconductor QDs, which enable their versatile applications in solar energy conversion, are analyzed. Recent applications of QDs in photocatalytic CO2 reduction are then introduced in three categories: binary II–VI semiconductor QDs (e.g., CdSe, CdS, and ZnSe), ternary I–III–VI semiconductor QDs (e.g., CuInS2 and CuAlS2), and perovskite‐type QDs (e.g., CsPbBr3, CH3NH3PbBr3, and Cs2AgBiBr6). Finally, the challenges and prospects in solar CO2 reduction with QDs in the future are discussed.
Carbon dioxide (CO2) photoreduction is regarded as an attractive pathway to produce value‐added chemicals and fuels. Recent advances in CO2 photoreduction via semiconductor quantum dots (QDs) in three categories are reviewed: II–VI, I–III–VI, and perovskite‐type QDs. Additionally, current challenges and prospects for QD‐photocatalyzed CO2 reduction are discussed.
Covalent organic frameworks have recently gained increasing attention in photocatalytic hydrogen generation from water. However, their structure-property-activity relationship, which should be ...beneficial for the structural design, is still far-away explored. Herein, we report the designed synthesis of four isostructural porphyrinic two-dimensional covalent organic frameworks (MPor-DETH-COF, M = H
, Co, Ni, Zn) and their photocatalytic activity in hydrogen generation. Our results clearly show that all four covalent organic frameworks adopt AA stacking structures, with high crystallinity and large surface area. Interestingly, the incorporation of different transition metals into the porphyrin rings can rationally tune the photocatalytic hydrogen evolution rate of corresponding covalent organic frameworks, with the order of CoPor-DETH-COF < H
Por-DETH-COF < NiPor-DETH-COF < ZnPor-DETH-COF. Based on the detailed experiments and calculations, this tunable performance can be mainly explained by their tailored charge-carrier dynamics via molecular engineering. This study not only represents a simple and effective way for efficient tuning of the photocatalytic hydrogen evolution activities of covalent organic frameworks at molecular level, but also provides valuable insight on the structure design of covalent organic frameworks for better photocatalysis.
In this paper, a novel first‐ and second‐order stabilization‐free virtual element method is proposed for two‐dimensional elastoplastic problems. In contrast to traditional virtual element methods, ...the improved method does not require any stabilization, making the solution of nonlinear problems more reliable. The main idea is to modify the virtual element space to allow the computation of the higher‐order L2$$ {L}_2 $$ projection operator, ensuring that the strain and stress represent the element energy accurately. Considering the flexibility of the stabilization‐free virtual element method, the elastoplastic mechanical problems can be solved by radial return methods known from the traditional finite element framework. J2$$ {J}_2 $$ plasticity with hardening is considered for modeling the nonlinear response. Several numerical examples are provided to illustrate the capability and accuracy of the stabilization‐free virtual element method.
Abstract
In this article, a novel weak‐form zonal Petrov–Galerkin free element method is proposed for two‐ and three‐dimensional linear mechanical problems. By absorbing the advantages of finite ...block method and strong‐form finite element method, the block mapping technique is used in the free element method. Combining the characteristics of the meshless local Petrov–Galerkin method, the local Petrov–Galerkin formulation based on the zonal free element method is formed at last. Besides, the local integral domain selected in the local collocation element is circular or spherical to simplify programming. The transformation of the local integral domain between the physical and normalized spaces is given for two‐ and three‐dimensional problems. The comparison of accuracy and convergence between the new proposed Petrov–Galerkin method and the conventional methods is carried out. Some challenging examples including fracture mechanics problems and a complex 3D problem are given to validate the convergence and accuracy of the proposed method.
Light‐driven multielectron redox reactions (e.g., hydrogen (H2) evolution, CO2 reduction) have recently appeared at the front of solar‐to‐fuel conversion. In this Minireview, we focus on the recent ...advances in establishing semiconductor quantum dot (QD) assemblies to enhance the efficiencies of these light‐driven multielectron reduction reactions. Four models of QD assembly are established to promote the sluggish kinetics of multielectron transfer from QDs to cocatalysts, thus leading to an enhanced activity of solar H2 evolution or CO2 reduction. We also forecast the potential applications of QD assemblies in other multielectron redox reactions, such as nitrogen (N2) fixation and oxygen (O2) evolution from H2O.
Join the dots: This Minireview focuses on the recent advances in constructing semiconductor quantum dot (QD) assemblies to enhance the efficiencies of light‐driven multielectron redox reactions, such as H2 evolution and CO2 reduction. Furthermore, their potential applications in N2 fixation and H2O oxidation is suggested.
We present a first-order stabilization-free virtual element method (VEM) for three-dimensional linear elastic problems in this paper. VEM has been increasingly used in various fields of engineering, ...but the need of stabilization yields a method that cannot be used without care, e.g. in nonlinear engineering applications. In this work, by increasing the order of the strain model, a new virtual element formulation is constructed for three-dimensional problems that does not require any stabilization term. The core concept involves adapting the virtual element space to enable the computation of a higher-order L2 projection operator, guaranteeing an accurate representation of the element energy in terms of strain and stress. This work describes the calculation process of the original H1 projection operator and the higher-order L2 projection operator for three-dimensional problems. Eigenvalue analysis allows to derive an approximate relation between the polynomial order and the number of element vertices. Some benchmark problems illustrate the capability of the stabilization-free VEM for three-dimensional linear elastic problems.
Enzymatic reactions and self-assembly are two fundamental attributes of cells. It is not surprising that one can use enzyme-instructed self-assembly (EISA)the integration of enzymatic transformation ...and molecular self-assemblyto modulate the emergent properties of supramolecular assemblies for controlling cell behaviors. The exploration of EISA for developing cancer therapy and imaging has made considerable progress over the last five years. In this Topical Review, we discuss these exciting results and the future promise of EISA. After describing several key studies to illustrate the progress of EISA in developing cancer therapy, we discuss the use of EISA for molecular imaging. Then, we give the outlook of EISA for developing supramolecular anticancer medicine that inhibits multiple hallmark capabilities of cancer.
In this paper, a novel higher stabilization-free virtual element method is proposed for compressible hyper-elastic materials in 2D. Different from the most traditional virtual element formulation, ...the method does not need any stabilization. The main idea is to modify the virtual element space to allow the computation of a higher-order polynomial L2 projection of the gradient. Based on that the stiffness matrix can be obtained directly which greatly simplifies the analysis process, especially for nonlinear problems. Hyper-elastic materials are considered and some benchmark nonlinear problems are solved to verify the capability and accuracy of the stabilization-free virtual element method.
Colloidal semiconductor quantum dots (QDs) have recently attracted widespread interest for diverse applications. Owing to their quantum confinement effects, rich surface binding properties, high ...surface‐to‐volume ratios, broad and intense absorption spectra in the visible region, and low cost as well, QDs offer new and versatile ways to serve as photocatalysts for organic synthesis. Most recently, the use of QDs photocatalysts is springing up in organic synthesis. Herein, we highlight the recent advances of QDs used for smart and clean organic transformations.
In this Concept article, recent advances of photocatalysis with quantum dots (QDs) and visible light for effective organic synthesis are highlighted.
New energy vehicles have gradually become one of the key parts in the development of the automotive field under the background of the new era. It is also to comply with the requirements for ...environmental protection. Therefore, this article analyzes the reasons for the excessive temperature of the generators of new energy vehicles, and proposes targeted improvement strategies in combination with the actual situation. While ensuring that the output torque of the new energy vehicle generator itself can be effectively increased, it can ensure that the basic requirements of the new energy vehicle to the greatest extent.
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