Bi-based semiconductor photocatalysts are important visible-light-driven photocatalysts. However, the photocatalytic performance of bulk bismuth-containing compounds remains unsatisfactory. Many investigations indicate that morphology control and surface modification are effective methods for improving the photocatalytic activity of these compounds. Herein, we review recent advances in this field, including ultrathin nanoplate fabrication, facet ratio control, hierarchical and hollow architecture construction, functional group and quantum-sized nanoparticle modification, surface defect regulation, and in situ formation of metal bismuth and bismuth compounds. The characteristics and advantages of these modification methods are introduced. In addition, mechanisms for improving light absorption, separation, and utilization of excited carriers are discussed. Trends in the development of Bi-based photocatalysts using morphology control and surface modification, as well as the challenges involved, are also analyzed
Conceptual density functional theory (DFT), also called Density Functional Reactivity Theory or Chemical DFT, is the chemical reactivity theory of DFT. Its framework and some recent developments of Conceptual DFT are briefly reviewed in this article. Introduced in more detail are the reactivity indices such as electronegativity, hardness, softness, Fukui function, electrophilicity index, as well as principles derived from them. Two representative recent developments, the dual descriptor and steric effect quantification, are succinctly summarized. A personal prospective on the future of Conceptual DFT is provided at the end.
This paper focuses on application of graphdiyne (GDY) in both energy storage and conversion fields, including the most recent theoretical and experimental progress. The unique three-dimensional pore structure formed by stacking of the GDY layer, make it possess the natural advantage which can be applied to lithium storage and hydrogen storage. Because of its lithium storage ability, GDY can be used in energy storage devices, such as lithium ion batteries and lithium ion capacitors. While with the hydrogen storage property, GDY can be used as a hydrogen storage material in fuel cells. By doping method, the performance of GDY for lithium and hydrogen storage can be further improved. Owing to acetylene units composed of sp hybridized carbon atoms and benzene rings composed of sp(2) hybridized carbon atoms, GDY possesses multiple conjugated electronic structures. Thus, its band gap can be regulated through many ways accompanied with existence of Dirac cones. This property means that GDY can not only be used as a
Sodium ion batteries (SIBs) have attracted increasing attention for energy storage systems because of abundant and low cost sodium resources. However, the large ionic radius of sodium and its slow electrochemical kinetics are the main obstacles for the development of suitable electrodes for high-performance SIBs. The development of high-performance cathode materials is the key to improving the energy density of SIBs and facilitating their commercialization. Herein, we review the latest advances and progress of cathode materials for SIBs, including transition metal oxides, polyanions, ferrocyanides, organic materials and polymers, and amorphous materials. Additionally, we have summarized our previous works in this area, explore the relationship between structure and electrochemical performance, and discuss effective ways to improve the reversibility, working potential and structural stability of these cathode materials.
Non-fullerene organic solar cells are of broad and current interest in the field of organic solar cells, and show promising application in high performance solar cells. When designing conjugated molecules as non-fullerene materials, several parameters, such as absorption, energy levels, charge transport, and crystallinity should be considered. Among them, absorption spectra are an important parameter that determine the efficiency of sun-light harvesting. In this work, we explore a new near-infrared electron acceptor naphthalenediimide-porphyrin (NDI-Por) by using electron-donating porphyrin as the core, and four NDI as end groups with ethynyl as linkers attached to the meso-position of porphyrin. This star-shaped molecule exhibits absorption spectra up to 900 nm. NDI-Por was incorporated into non-fullerene solar cells as an electron acceptor, and together with a wide-band gap polymer donor, an initial power conversion efficiency of 1.80% could be achieved. In particular, the solar cells exhibit a broad photo-
In recent years, organic solar cells (OSCs) have attracted increasing attention, and the power conversion efficiency (PCE) of OSCs has markedly improved. To enhance the photovoltaic properties of OSCs, it is important to develop the donor materials in the light-harvesting layer, which mainly include conjugated polymers and small molecules (SMs). Compared with polymeric materials, small-molecule materials have been widely investigated for their superior characteristics, such as well-defined molecular structures that can provide good batch-to-batch reproducibility. In this work, we synthesized three SM donor materials with theacceptor-donor-acceptor (A-D-A) structure by employing the trialkylthienyl-substituted benzodithiophene (TriBDT-T) unit as the D-core unit, and rhodanine (RN), cyano-rhodanine (RCN), and 1,3-indanone (IDO) as the A end groups, respectively. The optical properties, molecular energy levels, and thermogravimetic characteristics of the three SMs were studied; moreover, the blend morphologies a
As a new type of energy storage device, supercapacitors with high specific capacitance, fast charge and discharge, and long cycle life have attracted significant attention in the energy storage field. Electrode materials are a crucial factor defining the electrochemical performance of supercapacitors. The standard supercapacitor electrode materials used can be classified into three types: carbon-based materials, metal oxides and hydroxide materials, and conductive polymers. This review introduces the principles of supercapacitors and summarizes recent research progress of carbon-based electrode materials, including pure carbon materials, and the binary and ternary complex materials with carbon.
Solution-processable organic photovoltaic cells (OPVs) have attracted considerable interest. Over the past twenty years, fullerene and its derivatives have been predominately used as the electron acceptor materials to fabricate OPV devices. In recent few years, non-fullerene organic photovoltaic cells (NF-OPVs), consisting of polymers as the donors and the non-fullerene (NF) materials as the acceptors, have been developed rapidly, and the highest power conversion efficiencies of NF-OPVs exceed those of fullerene-based OPVs. In these NF-OPVs, both polymeric donor materials and NF acceptors play critical roles in achieving outstanding efficiencies, and hence, the molecular design of the polymer donors has been deemed a very important topic of research in the field. In this review, we will present an introduction of the specific requirements for polymer donors in NF-OPVs and summarize the recent progress related to polymer donors for the applications in highly efficient NF-OPVs.
To accurately predict the capability and possible reaction site for atoms in molecules to donate or accept electrons in chemical processes, i.e., to quantitatively determine electrophilicity, nucleophilicity, and regioselectivity, is an important yet incomplete task. Earlier, we proposed using the Hirshfeld charge and information gain as two equivalent descriptors for this purpose, based on the Information Conservation Principle we recently proposed. This idea was successfully applied to two series of molecular systems to confirm its validity. However, our previous work is hindered by the fact that the involved element is carbon. It is unclear if it applies to other elements and to different valence states of the same element. In this study, to address these issues, the method was applied to nitrogen-containing systems. Five different categories of compounds were studied, including benzenediazonium, azodicarboxylate, diazo, and primary and secondary amines, with a total of 40 molecules. The results show that
Carbon atoms can bond together in different molecular configurations leading to different carbon allotropes including diamond, fullerene, carbon nanotubes, graphene, and graphdiyne that are widely used or explored in a number of fields. Carbon dots (CDs), which are generally surface-passivated carbon nanoparticles less than 10 nm in size, are other new members of carbon allotropes. CDs were serendipitously discovered in 2004 during the electrophoresis purification of single-walled carbon nanotubes. Similar to their popular older cousins, fullerenes, carbon nanotubes, and graphene, CDs have drawn much attention in the past decade and have gradually become a rising star because of the advantages of chemical inertness, high abundance, good biocompatibility, and low toxicity. Interestingly, CDs typically display excitation-energy-and size-dependent fluorescent behavior. Depending on their structures, the fluorescence from CDs is either attributed to the quantum-confinement effect and conjugated p-domains of the c
Since the successful synthesis of graphdiyne, graphynes have emerged as an active field in carbon materials research. Hydrogen-substituted graphyne, structurally similar to graphynes, is a kind of two-dimensional (2D) carbon-rich material composed of sp(2)-hybridized carbon and hydrogen from phenyl groups and sp-hybridized carbon from ethynyl linkages. The large pore size in the molecular structure of hydrogen-substituted graphyne aids the diffusion of ions and molecules. In this work, hydrogen-substituted graphyne was synthesized by a facile mechanochemical route. Calcium carbide (CaC2) was employed as the precursor of sp-hybridized carbon and 1,3,5 tribromobenzene (PhBr3) as that of sp(2)-hybridized carbon and hydrogen. Hydrogen-substituted graphyne was directly obtained via the cross-coupling reaction performed by ball milling under vacuum and the impurities were removed by dilute nitric acid and benzene. Mechanochemistry is a mature technology for the simple and high-yield synthesis of nanostructured mate
Graphdiyne features sp and sp(2) hybridized carbon atoms. The direct natural band gap and Dirac cone structure for graphdiyne are believed to originated from inhomogeneous pi-bonding of differently hybridized carbon atoms and overlap of carbon 2p(z) orbitals. The special electronic structures and pore structures of graphdiyne are responsible for its potential and important applications in the fields of information technology, electronics, energy, catalysis, and optoelectronics. Recent basic and applied research studies of graphdiyne have led to important results; as a result, graphdiyne has become a new research field for carbon materials. The high activity of acetylenic units in graphdiyne provides a good platform for chemical modification and doping. Several approaches have been developed to modify the band gap of graphdiyne, including invoking strain, BN-doping, preparing nanoribbons, and hydrogenation, leading to a new graphdiyne (GDY) or graphyne (GY) derivatives. In this review, we summarize the recent
Benefitting from high-temperature operating conditions, solid GO oxide fuel cells (SOFCs) exhibit high electricity efficiency and can be coupled with conventional engines such as gas turbines, to achieve cascaded energy utilization. However, high temperature inevitably accelerates material deterioration, and simultaneously complicates the on-line diagnosis of SOFCs. Electrochemical impedance spectroscopy (EIS) is a mature on-line testing technology that is been widely used in SOFC research. Using EIS analyses, researchers can clearly determine the ohmic resistance of pure ion/electron conduction and the magnitude of the polarization impedance of electrochemical processes or diffusion. However, the lack of decomposition of polarization impedance constitutes a limitation for the deeper understanding 'YSZk of SOFC operation. To better utilize information-rich EIS, this work used a typical Ni-Y2O3 stabilized zirconia (Ni-YSZ) anode-supported SOFC and designed a complete set of impedance tests by modifying the tes
Recently, non-fullerene small molecular acceptors (NFSMAs) have received great attention because of their broad and strong absorption spectra and stable active layer morphology when compared with traditional fullerene acceptors. The most widely used strategy to design NFSMAs is through A-D-Atype molecules, in which an electron-rich core unit (D) is flanked by two electron-deficient units (A). In order to fine-tune the absorption spectra, energy levels, and photovoltaic properties of NFSMAs, great efforts have been made to modify the conjugated backbone of A-D-A type molecule acceptors. In a previous work, we developed a small molecular electron acceptor, namely MBN-Ph, with an A-D-A structure and an organoboron core unit. MBN-Ph exhibited distinctive absorption spectra with two absorption bands in short- and long-wavelength regions. It is known that side chains or substituents on small molecular electron acceptors can also play an important role in the molecular properties and photovoltaic performance of bulk
With the rapid development of science and technology, various nanomaterials have continually emerged to meet human needs. As a newly emerging class of nanomaterials, two-dimensional (2D) materials have received wide attention recently in energy storage, catalysis, sensing and biomedicine due to their unique features such as good mechanical property, high specific surface area, excellent thermal and electrical conductivity. Biomacromolecules are the special organic molecules with various biological activities which exist extensively in every aspect of human life. When 2D materials meet biomacromolecules to display their own unique advantages, more opportunities and challenges have arisen for the exploitation and fabrication of novel nanomaterials with unique electrical, mechanical, biological properties and specific functions. In recent years, extensive research has been carried out with outstanding achievement thus the combination of 2D materials and biomacromolecules becomes a new hotspot. There were general
Graphyne is a rapidly rising star material of carbon allotropes containing only sp and sp(2) hybridized carbon atoms forming extended two-dimensional layers. In particular, graphdiyne is an important member of graphyne family. With unique nanotopological pores, two-dimensional layered conjugated frameworks, and excellent semiconducting and optical properties, graphdiyne has displayed distinct superiorities in the fields of energy storage, electrocatalysis, photocatalysis, nonlinear optics, electronics, gas separation, etc. Therefore, the synthesis of high-quality graphdiyne is highly required to fulfill its potentially extraordinary applications. Furthermore, the development of a standardized and systematic set of characterization procedures is an urgent need, and would be based on intrinsic samples. However, there are still obvious barriers to synthesizing this newborn carbon allotrope that can be mainly considered as follows. The selection and stability of monomers is essential for synthesis. The synthesis
Interactions between surfactants and small organic molecules not only enhance the surface activity of the surfactants and induce aggregate transitions in them, but also improve the solubility and stability of the organic molecules. Understanding the interaction between surfactants and small molecules will help in widening the scope of application of surfactants. Folic acid, a member of the vitamin B family, has a pteridine ring, paraaminobenzoic acid, and glutamic acid, and is crucial for many reactions inside the human body. The unique structure of folic acid also facilitates the preparation of functional materials such as liquid crystals and gels. However, the poor solubility and precipitation of folic acid limit its applications. Therefore, it is essential to improve the solubility and stability of folic acid. Surfactants are efficient in solubilizing and stabilizing small molecules. The interactions of folic acid with four types of surfactants, namely, an anionic surfactant, sodium dodecyl sulfate (SDS);
Borophene, a boron analogue of graphene, exhibits a rich variety of chemical and physical properties. Here, we provide an intensive overview of recent progress in theoretical modeling and experimental synthesis of borophene. In particular, we analyze the influence of substrate, growth temperature, and precursor on the selectivity of boron nucleation. While three-dimensional (3D) bulk boron is more stable than a two-dimensional (2D) boron sheet, the nucleation barrier determined by the growth process controls the formation of the material and it depends on the specific growth environment. Theoretical studies have shown that a metal substrate can play an important role in stabilizing 2D boron clusters over their 3D form, resulting in the kinetically favored growth of 2D boron on the substrate even though the 2D boron clusters will be overwhelmingly less stable than the 3D form with increasing cluster size. Ag and Cu substrates have proven to be particularly suitable for achieving this preference. Guided by theo
Microorganisms exploit extracellular electron transfer (EET) with external minerals during their growth. This process is accompanied by the conversion of chemical energy. Direct electron transfer (DET) from the microorganisms to solid electron acceptors via membrane-bound cytochrome c enzymes or conductive nanowires/pili has been reported. In previous studies, mediated electron transfer (MET) has also been demonstrated to occur through electrochemically active metabolites acting as redox mediators. The microorganisms with EET capabilities have been harnessed for bioelectrochemical systems (BESs) in the bioremediation of environmental contaminants and the production of biofuels and nanomaterials. Electron transfer at the electrode biofilm/solution interface is one of the core phenomena occurring in BESs. The study of the redox reactions occurring in the microenvironment of the biofilm should elucidate the mechanism of microbial EET, which will then help improve the electron transfer efficiency of BESs. The com
As a potential substitute for commercial lithium ion batteries (LIBs), sodium ion batteries (NIBs) have attracted increasing interest during the last decade. However, compared to the LIBs, the sluggish kinetics of sodium ion diffusion in NIBs due to its larger ionic radius results in deteriorated electrochemical performances, which hinders the future development and application of NIBs. Therefore, exploring anode materials that exhibit a novel kinetic mechanism is desired. Recently, extremely rapid kinetics has been realized by introducing the pseudocapacitance effect into battery systems; this effect generally refers to faradaic charge-transfer reactions, including surface or near-surface redox reactions, and fast bulk ion intercalation. To obtain a pseudocapacitance effect in battery systems, the critical step involves the rational design of a two-dimensional structure with a high conductivity. In this regard, the bimetallic sulfide thiospinel NiCo2S4 stands out by virtue of its high conductivity (1.25 x 10