A series of spatiotemporally resolved surface photovoltage techniques were used to investigate the pho-togenerated charge transfer process within sub-picosecond to second timescale and at sub-micrometer level on single-particle cuprous oxide photocatalyst. A spatiotemporal charge transfer image was pictured. It is found that the high efficiency in charge separation of the facet-specific cuprous oxide single-particle originates mainly from the ultrafast quasi-ballistic inter-facet hot electron transfer process. These findings give a fascinating and deep insight into the photoinduced charge transfer mechanism in semiconductor photocatalyst, and pave a refreshed way to developing photocatalyst.

Metal nanoparticles released by human activities inevitably enter the aquatic environment. Numerous studies have shown that metal nanoparticles could induce reproductive toxicity and genetic toxicity in aquatic organisms. Furthermore, metal nanoparticles could be transmitted along the food chains which is a potential threat to human health. Quantitative analysis of intracellular metal nanoparticles is important for studying the biological effects of metal nanoparticles. In addition, there is heterogeneity among cells, and the individual cell with special physiological characteristics may influence or even determine the destiny of the cell population. However, most traditional methods for the quantitative determination of intracellular metal nanoparticles were based on the whole cell population whereas the heterogeneity of individual cells was neglected, which may result in the loss of significant information about cell populations that have important functions to the community. Therefore, the quantitative analysis of the intracellular metal nanoparticles in unicellular microorganisms, which locates at the bottom of the trophic level in the aquatic environment, is essential for understanding the interaction between metal nanoparticles and aquatic organisms and evaluating the potential risk of metal nanoparticles entering the food chain. In this review, we discuss the single-cell analysis methods for the quantitative determination of metal nanoparticles in aquatic unicellular organisms. The working principle and application of these methods and their pros and cons are summarized. This paper aims to provide a theoretical basis of the method selection for relevant studies in the future. Finally, we prospect the future research directions in this field according to the current research status.

Chiral inorganic nanomaterials have attracted much attention due to their excellent photophysical properties and wide potential applications. The chiral structure obtained by modifying the surface of inorganic nanomaterials with chiral ligands or assembling inorganic nanomaterials with chiral templates can strongly interact with photons to change the polarization and generate circularly polarized light (CPL). In terms of generation mechanism, CPL mainly includes circularly polarized luminescence and circularly polarized scattering, and in some cases these two mechanisms coexist. This article summarizes the progress of CPL in semiconductor nanomaterials, metal nanoclusters, perovskites, lanthanide complexes and other composite nanomaterials. In addition, the main source of CPL in different chiral inorganic nanomaterials is also discussed. The conclusions drawn in this review are expected to realize regulating the anisotropy factor of CPL active materials at the molecular level and promote their development in various applications such as quantum computing, information encryption, 3D displays, and optical sensing.

Coenzyme NADH-dependent oxidoreductases are widely used in the fields of fine chemical synthesis and chiral drug development. As a reducing equivalent, NADH plays a key role in oxidoreductase catalysis. In view of the stoichiometric consumption and high cost of NADH, the search for green, feasible and efficient coenzyme regeneration strategies is an important but challenging task. In recent years, photo/(electro)-catalytic method for NADH regeneration has received extensive attention. In this paper, starting from the Z-scheme reaction that simulates natural photosynthesis, based on the photo-induced electron transfer and hole capture in the process of photo/(electro)-catalytic coenzyme regeneration, some recent works related to NADH regeneration are reviewed. The review is expected to provide ideas for further design of efficient coenzyme regeneration system. In addition, the research progress on NADH-dependent photo-enzyme synergistic catalysis in recent years is also briefly introduced, and an outlook is tentatively attempted about the challenges of the biomimetic photocatalytic coenzyme regeneration system and the future developments of photo-enzyme coupling system.

Organic carbon materials are widely used in the field of photoelectrocatalysis because of their high charge conduction efficiency, adjustable structure and no pollution. The catalyst containing organic carbon as electrode material has become one of the research hotspots in the field of photoelectrocatalysis. The structure and characteristics of several common organic carbon materials are introduced in this paper. These preparation methods and research direction of photoelectrocatalysis are also elaborated. And the electrodes containing organic carbon were divided into three categories. Five functions of organic carbon materials in photoelectric catalytic system are summarized and discussed: (1) act as catalyst; (2) act as photosensitizer; (3) act as electronic medium; (4) act as carrier; (5) act as photoelectrode stabilizer. In the end the research status and difficulties of organic carbon materials in photoelectrocatalytic system are also described in this paper.

Single-atom catalysts (SACs) have been attracting ever-increasing interest in the fields of both fundamental research and industry applications, for their unique advantages such as high atomic utilization efficiency, high activity, and high selectivity. On the other hand, the preparation of SCAs is still quite challenging. A proper carrier of the active atoms is crucial for the preparation of SCAs, which affects the stability, electron structure, and thus reactivity. MXene, a novel series of two-dimensional inorganic materials with large specific surface area, adjustable bandgap, superior electronic conductivity, as well as abundant anchor sites have emerged as an ideal platform for confining single atoms. Herein, the structural superiority and synthetic strategies of MXene as SCAs support are reviewed. The unique structure and property of MXene based SACs make the material superior for electrochemical catalysis. Here the reactions including hydrogen evolution reaction (HER), oxygen evolution reaction (OER), nitrogen reduction reaction (NRR), carbon dioxide reduction reaction (CRR), as well as battery energy storage are highlighted. Finally, the challenges and opportunities of MXene based SACs in the fields of research and practical applications are summarized and prospected. It is hoped that this review article could provide insights for the development of advanced MXene-based SCAs.

Small peptides are the ideal material to construct artificial enzymes due to their advantages of high similarity to natural enzymes and controllable structure. Small peptides have more simple structures which makes them convenient for rational design. Meanwhile, the diversity of amino acids arrangement, self-assembly characteristics of the sequence, the stability of the nanostructure, and good biocompatibility make it possible to construct high-efficiency catalytic active peptide-based artificial enzymes with broad application prospects. There are many advantages to using peptide-based materials for rationally designing active sites to construct artificial enzymes. (1) The amino acid sequences can be derived directly from the active sites in the natural enzyme, therefore preserving the function of enzymes but reducing much of the complexity that is inherent to nature enzymes; (2) Various active sites with specific structures and functions can be embedded in the peptide sequence, which is convenient for the artificial rational design of the artificial enzymes. (3) Peptides have good biocompatibility and hydrolysis reaction under mild conditions. According to the different catalytic degradation of the chemical bond, the peptide-based artificial hydrolases are mainly divided into the following categories: catalytic ester bond degradation peptide-based artificial enzyme, catalytic peptide bond degradation peptide-based artificial enzyme, catalytic glycosidic bond degradation peptide-based artificial enzyme. Therefore, this review mainly summarizes the peptide-based artificial hydrolase from activity origin, construction methods, microstructure, catalytic reaction type, catalytic influencing factors, activity improvement methods, activity mechanism, and future application. To promote the designing of peptide-based artificial enzymes with more efficient catalytic activity, accelerate the development and practical application of peptide-based artificial hydrolase.

Metal-organic frameworks (MOFs), featuring the ordered porous structure and abundant topology, have been widely concerned and thoroughly reviewed according to its application prospects in recent years. Although the metal center is critical to the structure and performance of MOFs, summaries of the MOFs with a specific central metal are still few at present. As the only heavy metal element with considerable abundance and low toxicity, bismuth-based metal-organic frameworks (Bi-MOFs) stand out among MOFs for its innocuousness and biocompatibility. It would be a significant direction to design legitimately, synthesize successfully, and exploit steadily the Bi-MOFs with rich structures in the current MOFs research. However, this specific type of MOFs is still in its infancy, which is limited by the flexible coordination environment and low solubility of Bi (Ⅲ) cation. The synthesis of Bi-MOFs in the aqueous solution has always been an enormous challenge resulting from the hydrolysis of the bismuth salt. Herein, this article reviews the common ligands and general synthesis methods of Bi-MOFs in recent years, focusing on its application in photocatalysis, electrocatalysis, drug carriers, gas adsorbents and electrode materials. By profusely discussing the mechanism and reaction rules in catalytic reactions, this review aims to provide rewarding references for similar catalytic reactions to improve reaction efficiency and save costs. In addition, to highlight the unique advantages of Bi-MOFs, we make detailed comparisons with traditional materials. Some expanded applications of energy storage (mainly cationic battery energy storage), adsorption separation (selective adsorption of anions and enrichment of energy gas), drug delivery (the encapsulation and release of specific drugs) are also supplemented. For consideration of existing research, our work puts forward a prospect for future pioneering research to stimulate the research progress of Bi-MOFs.

Adsorptive separation has been widely used in petroleum, chemical, pharmaceutical, environmental protection and many other fields due to the advantages of high efficiency and low-energy consumption. Therein, the structural characteristics (such as specific surface area, pore size, pore volume, surface functional groups, etc.) of the adsorbent are the key factors that affect the adsorption capacity and separation efficiency. Metal-organic framework (MOF) materials have excellent pore structures and abundant functional groups (—NH₂, —CHO, etc.), which can be easily post-modified and functionalized with specific functions, thus enhancing the interaction between MOFs and adsorbates and achieving high adsorption capacity and separation selectivity. In this context, the synthesis strategies of MOF-NH₂/CHO materials were firstly outlined, then the research progress of imine covalently post-modified MOF (ICPSM-MOF) materials was summarized, and their applications in gas and liquid adsorption separation were emphasized. In addition, the difficulties and challenges faced by the current ICPSM-MOFs were finally analyzed, and the future research trend of ICPSM-MOFs was also put forward.

Since the demonstration of organic room temperature phosphorescence (ORTP) from carbazole in 2008, using carbazole unit to construct ORTP materials has become a feasible approach to developing a series of diverse, high-performance, widely applicable and highly representative ORTP material system. This review paper firstly summarizes three strategies for improving phosphorescence performance of ORTP materials, namely H-aggregation, heavy-atom effect and donor-acceptor structure. Then, the recent progress of crystalline carbazole-based ORTP materials is systematically introduced. Based on these three strategies, triplet relaxation is suppressed, spin-orbital coupling is enhanced, singlet-triplet energy gaps are reduced, and intermolecular charge transfer interactions are strengthened. As a result, the triplet excited states are stabilized, and intersystem crossing is accelerated to facilitate phosphorescence, and thereby realizing long-lifetime high-efficiency crystalline carbazole-based ORTP materials. Their applications in the fields of anti-counterfeiting, information security and bioimaging are briefly discussed.

Artificial cells are micro-vesicles that are artificially engineered to possess some structures and functions, similar to biological cells. There are two approaches for fabricating artificial cells. The top-down approach mainly makes a kit in biological methods to redesign and modify biological gene sequences to create artificial cells, and the bottom-up approach mainly adopts chemical methods to prepare protocell models from non-living matter. Here we review in detail towards the different chemically constructed artificial cells, including lipid vesicles, proteosomes, polymersomes, coacervate droplets and colloidosomes. Taken together, this minireview unravels an update on recent efforts in biomedical applications of artificial cells over a broad range of analytical sensing, cell structure and function simulation, biological cargo delivery, micro-nano reactors, and disease diagnosis and treatment.

Janus particles are usually composed of parts with two or more different physical or chemical properties, and are characterized by structural asymmetry, which leads to asymmetries in particle morphology and physical properties. Compared with static Janus particles, dynamic Janus particles, which can realize stimuli-response, can interact with the environment well to express their special role in a specific environment under external stimulus. Photoresponsive Janus particles are asymmetric particles that can respond to specific light stimuli. Different materials on both sides of Janus particles can not only compound with different types of photoresponse, but also can compound with other types of stimuli-responses, to achieve precise regulation of specific systems. Because the energy of light can be easily regulated, photoresponsive Janus particles can produce specific reactions to inorganic nanoclusters or organic functional groups. So photoresponsive Janus particles can present photothermal effect, color adjustment, photodynamic therapy and other unique properties. They can also be applicated in drug delivery, biological sensing and imaging, micro nanomotors and photoluminescence, which provides a new way to solve problems in the field of biomedicine and optical devices. In this paper, the recent development of preparation methods of inorganic and polymeric photoresponsive Janus particles are introduced, and their unique regulatory mechanism and outstanding applications in the fields of biomedicine and luminescent materials are emphasized. Finally, the challenges and development prospects in this field are discussed.

Photodynamic therapy is a safe and noninvasive treatment method based on photosensitizers and light. It has broad application prospects in cancer treatment and sterilization. Photosensitizers react with oxygen under light excitation to produce reactive oxygen species with high reactivity. Excessive reactive oxygen species in cells can oxidize and damage cellular components such as proteins, nucleic acids and lipids, and induce cell apoptosis or necrosis. The emerging photosensitizers with aggregation-induced emission (AIE) characteristics can emit strong fluorescence under light excitation in the aggregate state, and efficiently produce reactive oxygen species at the same time, which solves the problem of fluorescence quenching of traditional photosensitizers in the aggregate state. AIE photosensitizers are easy to realize image-guided photodynamic therapy, which has attracted much attention in recent years. Mitochondria, as cell energy factories, are rich in oxygen and are ideal targets for photodynamic therapy. Mitochondria are more numerous in cancer cells and play an important role in both tumorization and programmed cell death. Currently, the AIE photosensitizers targeting the mitochondria of cancer cells are mainly cationic compounds, including pyridium ions, quinolinium ions, isoquinolinium ions and triphenylphosphenonium ions. This review summarizes the molecular types and design strategies of AIE photosensitizers targeting the mitochondria of cancer cells, as well as their applications in photodynamic therapy of tumors.

The social demand for energy is highly increasing because of the rapid development of economy. On the other hand, environmentally safe treatment of industrial wastewater is required to raise to a higher standard. Photocatalytic fuel cell (PFC), which adopts the photocatalytic electrode in the fuel cell configuration, can achieve the dual functions of efficient degradation of organic pollutant and simultaneous electricity generation. Therefore, PFC promises to have potential applications in harmless disposal and resource utilization of wastewater. The photocatalytic electrode is the core component of PFC system. The enhancement for the light activation of the photocatalytic electrode and the improvement of the separation rate of photogenerated carriers become the key strategies to improve the performance. In addition, the reactor design and optimization of operational parameters are also beneficial to improve the PFC performance. In this review, the basic principle of PFC has been introduced, and the progress of PFC in the treatment of environmental pollutants has also been reviewed. The optimization of PFC system for enhancing the pollution control performance and electricity generation efficiency has also been discussed in detail. This review provides theoretical guidance for further research of efficient and stable PFC systems for the wastewater treatment and energy recovery.

Lithium-selenium batteries have attracted much attention as secondary batteries due to their high energy density, high specific volumetric capacity, and moderate output voltage. However, the practical application of Li-Se batteries is hindered by the shuttle effect, poor conductivity, low active material utilization and fast capacity fading. In recent years, researchers investigated the charge-discharge mechanism of Li-Se batteries thoroughly, and studied effects on electrochemical performance from various new materials, including carbon materials and metal compounds, as cathode host, interlayer and electrolyte additives at the same time. This review systematically summarized the research progress of electrode materials, interlayer and electrolyte additives, with focus on charge-discharge mechanism and system optimization. We hope this review could provide perspective for the further development of Li-Se batteries.

Drug-resistance bacterial and biofilm-related infectious diseases pose a significant threat to the global public health. Focusing on the drug-resistance mechanisms of bacteria to antibiotics, we aim at presenting the research progress of nanomaterial-based antibacterial agents. This review starts with clarifying nanomaterials with unique physicochemical characteristics, which act as intrinsic antibacterial agents. Subsequently, we discuss nanomaterial-based artificial enzymes, which can kill bacteria with reactive oxygen species (ROS). Furthermore, nanomaterial-based multiple synergetic modality nanoplatforms are constructed to combat infections. These multifunctional antibacterial agents, either microenvironment-oriented or external stimulants responsive, coordinate new treatments for precise medication and integration of diagnoses and treatments. In addition, the challenges and clinical prospects of these nanomaterial-based antibacterial agents are discussed, providing new perspectives of developing safer and more efficient antibacterial agents.