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As a representative composite metal oxide belonging to a perovskite, strontium titanate (SrTiO 3 ) possesses the merits of chemical stability, low toxicity and low cost, endowing it with significant application potentials in environmental remediation, clean energy generation and valuable chemical production from greenhouse gas conversion. However, the pure-phase SrTiO 3 suffers from many fatal weaknesses, especially the wide energy bandgap and low photoexcited electron–hole pair separation efficiency, thus limiting its photocatalytic performance and large-scale applications. To address this issue, researchers have made great efforts to modify the electronic and physicochemical structure of SrTiO 3 . In particular, doping treatments have attracted considerable attention, but some problems still block effective doping, while impropriate doping might worsen the photocatalytic performance of SrTiO 3 by introducing the photogenerated hole–electron pair recombination centres. Consequently, many challenges remain for this research topic that is undergoing an intense study. This short review presents the hot spots of appropriate doping treatments of SrTiO 3 for photocatalytic performance enhancement over recent years. Different kinds of doping species are systematically discussed. The current problems that remain are summarized and analysed, and the perspectives for the rational doping of SrTiO 3 are presented. Graphical abstract

Nonmetallic co-doping and surface hole construction are simple and efficient strategies for improving the photocatalytic activity and regulating the electronic structure of g-C3N4. Here, the g-C3N4 catalysts with B-F or B-S co-doping combined with nitrogen vacancies (Nv) are designed. Compared to the pristine g-C3N4, the direction of the excited electron orbit for the B-F-co-doped system is more matching (N2pz→C2pz), facilitating the separation of electrons and holes. Simultaneously, the introduced nitrogen vacancy can further reduce the bandgap by generating impurity states, thus improving the utilization rate of visible light. The doped S atoms can also narrow the bandgap of the B-S-Nv-co-doped g-C3N4, which originates from the p-orbital hybridization between C, N, and S atoms, and the impurity states are generated by the introduction of N vacancies. The doping of B-F-Nv and B-S-Nv exhibits a better CO2 reduction activity with a reduced barrier for the rate-determining step of around 0.2 eV compared to g-C3N4. By changing F to S, the origin of the rate-determining step varies from *CO2→*COOH to *HCHO→*OCH3, which eventually leads to different products of CH3OH and CH4, respectively.

Cost-effectively, eco-friendly rechargeable aqueous zinc-ion batteries (AZIBs) have reserved widespread concerns and become outstanding candidate in energy storage systems. However, the progress pace of AZIBs suffers from limitation of suitable and affordable cathode materials. Herein, a double-effect strategy is realized in a one-step hydrothermal treatment to prepare V 2 O 5 nanoribbons with intercalation of Ce and introduction of abundant oxygen defects (O d -Ce@V 2 O 5 ) to enhance electrochemical performance synergistically. Coupled with the theoretical calculation results, the introduction of Ce ions intercalation and oxygen vacancies in V 2 O 5 structure enhances the electrical conductivity, reduces the adsorption energy of zinc ions, enlarges the interlayer distance, renders the structure more stable, and facilitates rapid diffusion kinetics. As expected, the desirable cathode delivers the reversible capacity of 444 mAh·g −1 at 0.5 A·g −1 and shows excellent Coulombic efficiency, as well as an extraordinary energy density of 304.9 Wh·kg −1 . The strategy proposed here may aid in the further development of cathode materials with stable performance for AZIBs.

Electrocatalytic water splitting seems to be an efficient strategy to deal with increasingly serious environmental problems and energy crises but still suffers from the lack of stable and efficient electrocatalysts. Designing practical electrocatalysts by introducing defect engineering, such as hybrid structure, surface vacancies, functional modification, and structural distortions, is proven to be a dependable solution for fabricating electrocatalysts with high catalytic activities, robust stability, and good practicability. This review is an overview of some relevant reports about the effects of defect engineering on the electrocatalytic water splitting performance of electrocatalysts. In detail, the types of defects, the preparation and characterization methods, and catalytic performances of electrocatalysts are presented, emphasizing the effects of the introduced defects on the electronic structures of electrocatalysts and the optimization of the intermediates' adsorption energy throughout the review. Finally, the existing challenges and personal perspectives of possible strategies for enhancing the catalytic performances of electrocatalysts are proposed. An in‐depth understanding of the effects of defect engineering on the catalytic performance of electrocatalysts will light the way to design high‐efficiency electrocatalysts for water splitting and other possible applications. Designing practical electrocatalysts by introducing defect engineering is proven to be a dependable solution for fabricating electrocatalysts with high catalytic activities, robust stability, and good practicability. This review focuses on illustrating the effects of defect engineering on electrocatalysts for water electrolysis. The existing challenges and personal perspectives of possible strategies for enhancing the catalytic performances of electrocatalysts are proposed.

Carbon dots (CDs) display tunable photoluminescence and excitation-wavelength dependent emission. The color of fluorescence is affected by electronic bandgap transitions of conjugated π-domains, surface defect states, local fluorophores and element doping. In this review (with 145 refs.), the studies performed in the past 5 years on the relationship between the fluorescence mechanism and modes for modulating the emission color of CDs are summarized. The applications of such CDs in sensors and assays are then outlined. A concluding section then gives an outlook and describes current challenges in the design of CDs with different emission colors. Graphical abstract Schematic representation of the relationship between the color-emitting (blue, green, yellow, red and multicolor) modulation of carbon dots and fluorescence mechanism including bandgap transitions of conjugated π-domains and surface defect states.

Diamond-like carbon (DLC) films with excellent anti-friction and wear resistance, can effectively reduce the energy loss of tribosystems and the wear failure of parts, but the high residual stress limits their application and service life. Researchers found that doping heterogeneous elements in the carbon matrix can alleviate the defects in the microstructure and properties of DLC films (reduce the residual stress; enhance adhesion strength; improve tribological, corrosion resistance, hydrophobic, biocompatibility, and optical properties), and doping elements with different properties will have different effects on the structure and properties of DLC films. In addition, the comprehensive properties of DLC films can be coordinated by controlling the doping elements and their contents. In this paper, the effects of single element and co-doping of carbide-forming elements (Nb, W, Mo, Cr, Ti, Si) and non-carbide-forming elements (Cu, Al, Ag, Ni) on the properties of microstructure, mechanical, tribological, optical, hydrophobic, corrosion resistance, etc. of DLC films are reviewed. The mechanisms of the effects of doping elements on the different properties of DLC films are summarized and analyzed.

Bifunctional catalysts for hydrogen/oxygen evolution reactions (HER/OER) are urgently needed given the bright future of water splitting hydrogen production technology. Here, the self-supporting N and Ce dual-doped NiCoP nanoarrays (denoted N,Ce-NiCoP/NF) grown on Ni foam are successfully constructed. When the N,Ce-NiCoP/NF simultaneously acts as the HER and OER electrodes, the voltages of 1.54 and 2.14 V are obtained for driving 10 and 500 mA·cm −2 with a robust durability, and demonstrate its significant potential for practical water electrolysis. According to both experiments and calculations, the electronic structure of NiCoP may be significantly altered by strategically incorporating N and Ce into the lattice, which in turn optimizes the Gibbs free energy of HER/OER intermediates and speeds up the water splitting kinetics. Moreover, the sprout-shaped morphology significantly increases the exposure of active sites and facilitates charge/mass transfer, thereby augmenting catalyst performance. This study offers a potentially effective approach involving the regulation of anion and cation double doping, as well as architectural engineering, for the purpose of designing and optimizing innovative electrocatalysts.

Microplastics (MPs) pose a profound environmental challenge, impacting ecosystems and human health through mechanisms such as bioaccumulation and ecosystem contamination. While traditional water treatment methods can partially remove microplastics, their limitations highlight the need for innovative green approaches like photodegradation to ensure more effective and sustainable removal. This review explores the potential of nanomaterial-enhanced photocatalysts in addressing this issue. Utilizing their unique properties like large surface area and tunable bandgap, nanomaterials significantly improve degradation efficiency. Different strategies for photocatalyst modification to improve photocatalytic performance are thoroughly summarized, with a particular emphasis on element doping and heterojunction construction. Furthermore, this review thoroughly summarizes the possible fundamental mechanisms driving the photodegradation of microplastics facilitated by nanomaterials, with a focus on processes like free radical formation and singlet oxygen oxidation. This review not only synthesizes critical findings from existing studies but also identifies gaps in the current research landscape, suggesting that further development of these photocatalytic techniques could lead to substantial advancements in environmental remediation practices. By delineating these novel approaches and their mechanisms, this work underscores the significant environmental implications and contributes to the ongoing development of sustainable solutions to mitigate microplastic pollution.

Lithium-ion batteries are considered a promising energy storage technology in portable electronics and electric vehicles due to their high energy density, competitive cost, and environmental friendliness. Improving cathode materials is an effective way to meet the demand for better batteries, of which the utilization of high-voltage cathode materials is an important development trend. In recent years, lithium-rich layered oxides have gained great attention due to their desirable energy density. This review presents the relationships between lattice structure and electrochemical properties, the underlying degradation mechanisms, and corresponding modification strategies. The recent progress and strategies are then highlighted, including element doping, surface coating, morphology design, size control, etc. Finally, a concise perspective for future developments and practical applications of lithium-rich layered oxides has been provided.