In covalent organic frameworks (COFs), the highly symmetric skeleton limits O₂ adsorption and weakens the thermodynamic driving force of the two-electron oxygen reduction reaction (2e⁻ ORR), thus restricting photocatalytic efficiency. In this study, we modulated the local arrangement of fluorine atoms in COFs (para- and ortho-fluorinated, named Fp-COFs and Fo-COFs) to create an asymmetric electronic distribution, which supplies effective O₂-adsorption sites, strengthens the driving force for 2e⁻ ORR and ultimately elevates the photocatalytic activity. Theoretical analysis shows that asymmetric fluorination delocalizes the lone-pair electrons of F atoms to adjacent carbons, producing a discretized electron distribution that improves O₂ adsorption at imine bonds. The increased electron density on these carbons facilitates electron transfer into the π* orbital of adsorbed O₂, accelerating ·OOH* intermediate formation and lowering the Gibbs free energy barrier of the 2e⁻ pathway. Consequently, a quantum yield of 8.8% for H₂O₂ photosynthesis in pure water is achieved. This work provides a new approach for tuning local electron distribution in COFs, offering guidance for the rational design of efficient photocatalytic materials and broadening the application prospects of asymmetric electronic structures.

The photocatalytic reduction of soluble U(VI) to insoluble U(IV) stands out as a viable strategy for sustainable uranium-contaminated water treatment. However, the development of efficient, robust photocatalysts remains challenging. Here, we fabricate a layered MBene (MoB) coupled with CdS to form a robust nanocomposite that enables rapid visible‑light‑driven reduction of U(VI). The 5%MoB/CdS composite achieves 97.4% U(VI) removal within 10 min without sacrificial agents, displaying fast apparent kinetics, strong tolerance to common coexisting ions, and excellent cyclic stability. Radical‑trapping experiments and electron spin resonance (ESR) measurements indicate that photogenerated electrons and superoxide radicals (•O₂^- ) are the primary active species driving U(VI) reduction. Kelvin probe force microscopy (KPFM) and femtosecond time-resolved transient absorption spectroscopy (fs-TAS) directly reveal enhanced interfacial charge transfer and prolonged carrier lifetime. Density functional theory (DFT) calculations reveal favorable band alignment and the formation of a Schottky barrier at the MoB/CdS interface, which directs electron transfer from CdS to the highly conductive layered MoB and suppresses charge recombination. The outstanding performance originates from the high conductivity and abundant active sites of sheet-like MoB, which facilitate electron extraction and offer numerous reduction sites. This work introduces a strategy for constructing highly efficient MBenes-based photocatalysts for uranium remediation.

The development of high-performance glucose sensors is of great significance for blood glucose monitoring and diabetes management. In this work, we designed and synthesized a novel nanocomposite electrocatalyst featuring hierarchical yolk–shell structured CuO/Co₃O₄@Co₃O₄ hybridized with graphitic carbon nitride (g-C₃N₄). The electrocatalytic performance for glucose oxidation was significantly enhanced by optimizing the mass ratio of the CuO/Co₃O₄@Co₃O₄ yolk–shell nanocubes to g-C₃N₄. The optimized composite electrode (with a 5:1 mass ratio) demonstrated exceptional sensing with an ultra-fast response (2 s) and recovery (4 s), outstanding reproducibility and excellent anti-interference capability. When engineered into a screen-printed electrode platform, this sensor achieved a sensitivity of 0.12 μA/(μM·cm²) with a wide linear detection range from 0.001 to 2.0 mM. Density functional theory (DFT) calculations reveal that the combination of CuO and Co₃O₄ can break the charge symmetry on Co atoms, enhance the material’s activity, as well as stronger adsorption for glucose, accelerating the accumulation of target molecules on the sensor surface during detection. Furthermore, a portable sensing device was successful developed by integrating this fabricated sensor with a miniaturized potentiostat. The superior electrocatalytic activity of CuO/Co₃O₄@Co₃O₄/g-C₃N₄ nanocomposite establishes a highly promising candidate for non-enzymatic glucose sensing technologies.

While thermal air exfoliation is widely used to prepare graphitic carbon nitride (g-C₃N₄) nanosheets, the effects of calcination conditions and atmosphere on their electronic structure and photocatalytic CO₂ reduction reaction (CO₂RR) performance remain systematically unexplored. We prepared g-C₃N₄ nanosheets with varying thickness and defects by controlling exfoliation parameters. The obtained nanosheets calcined longest in air exhibited highest CO₂RR activity, twice that of bulk g-C₃N₄. The comprehensive analysis of structural characterizations indicates the thickness of g-C₃N₄ nanosheets became thinner, and the defects increased as the calcination time increased. The N vacancies (N_v) and O-doping caused by N₂ and O₂ from air, respectively, enable valence band elevation (N_v) and conduction band depression (O-doping) that collectively redistribute the electronic structure. Nitrogen/oxygen dual-defects generated impurity levels, reduced the work function and band gap of g-C₃N₄ nanosheets, and served as shallow traps for photogenerated e⁻. The results of in-situ spectroscopy indicate these increased effective e⁻ are enriched around of N atoms to react with the adsorbed CO₂. During the CO₂ reduction process, the N_v promoted the formation of *COOH, and this dual-defect co-promoted the *CO desorption, resulting in the improved CO₂RR activity. These results comprehensively analyze the regulatory effect of thermal air calcination on the electronic structure of g-C₃N₄, providing valuable insights for designing g-C₃N₄ nanosheets based photocatalysts for CO₂RR.

Photocatalytic water bacterial inactivation is a promising strategy for microorganism removal from water, but the fabrication of efficient visible light-driven photocatalytic disinfection materials remains a challenge. Herein, In₂O₃/red phosphorus (In₂O₃/RP) hollow fibers were created through a chemical vapor deposition strategy to enhance photocatalytic water disinfection efficiency. The optimized In₂O₃/RP heterostructure exhibited rapid and effective bacterial inactivation of Escherichia coli (7-log CFU·mL⁻¹) within 10 min under white light-emitting device (LED) illumination. The enhanced photocatalytic bacterial inactivation performance can be attributed to the synergistic improvement in light absorption by RP decoration, as well as the enhanced charge separation and migration capacity at the interface between RP and In₂O₃. This led to the more unpaired photogenerated carriers transfer to the photocatalysts surface, thus promoting the production of photoexcited holes, ·O₂⁻, and ·OH radicals essential for efficient destruction of bacterial cells.

Accurate and sensitive detection of uric acid (UA) is crucial, as abnormal UA levels are often indicative of various diseases. This work introduces a straightforward electrochemical sensor utilizing a two-dimensional (2D) nanocomposite of S-doped g-C₃N₄ (SCN) and V₂CT_x MXene (SCN/V₂C), which was prepared via ball milling followed by calcination. The SCN/V₂C nanocomposite demonstrates superior conductivity and a reduced band gap relative to pure g-C₃N₄, leading to improved electrochemical performance for UA detection. Differential pulse voltammetry (DPV) measurements revealed a limit of detection (LOD) of 1 μM for UA and a linear response range spanning from 3 μM to 1 mM. Furthermore, experimental results confirmed the excellent stability of the SCN/V₂C nanocomposite. Density functional theory (DFT) calculations revealed that SCN/V₂C acts as a powerful electron donor, while UA functions as an efficient electron acceptor. The electron transfer between SCN/V₂C and UA is significantly greater than that with other common interfering biological molecules, leading to the highest adsorption energy of UA on the SCN/V₂C surface. This strong interaction accounts for the sensor’s exceptional selectivity. This newly developed sensor provides a straightforward and highly sensitive approach for the electrochemical detection of trace levels of UA in real biological samples.

A comprehensive research experiment was designed for the preparation of ascorbic acid modified MXene Ti₃C₂ (MXene/VC) and its application in electrochemical detection of p-nitrophenol. Firstly, the Al species of Ti₃AlC₂ was removed by acid-etching to synthesize MXene-Ti₃C₂. Secondly, the MXene/VC material was fabricated by modifying MXene-Ti₃C₂ with VC. Subsequently, the MXene/VC material was characterized by infrared spectroscopy, scanning electron microscopy and X-ray photoelectron spectroscopy. Finally, the differential pulse voltammetry (DPV) method was employed to systematically analyze the electrochemical detection of p-nitrophenol. The whole experimental process included multiple steps, such as literature consult, material preparation, microscopic characterization, electrochemical sensing performance testing and experimental report writing, which is conducive to the improvement of students' comprehensive quality.

g-C₃N₄ emerges as a promising metal-free semiconductor photocatalyst due to its cost-effectiveness, facile synthesis, suitable visible light response, and robust thermal stability. However, its practical application in photocatalytic hydrogen evolution reaction (HER) is impeded by rapid carrier recombination and limited light absorption capacity. In this study, we successfully develop a novel g-C₃N₄-based step-scheme (S-scheme) heterojunction comprising two-dimensional (2D) sulfur-doped g-C₃N₄ nanosheets (SCN) and one-dimensional (1D) FeCo₂O₄ nanorods (FeCo₂O₄), demonstrating enhanced photocatalytic HER activity. The engineered SCN/FeCo₂O₄ S-scheme heterojunction features a well-defined 2D/1D heterogeneous interface facilitating directed interfacial electron transfer from FeCo₂O₄ to SCN, driven by the lower Fermi level of SCN compared to FeCo₂O₄. This establishment of electron-interacting 2D/1D S-scheme heterojunction not only facilitates the separation and migration of photogenerated carriers, but also enhances visible-light absorption and mitigates electron-hole pair recombination. Band structure analysis and density functional theory calculations corroborate that the carrier migration in the SCN/FeCo₂O₄ photocatalyst adheres to a typical S-scheme heterojunction mechanism, effectively retaining highly reactive photogenerated electrons. Consequently, the optimized SCN/FeCo₂O₄ heterojunction exhibits a substantially high hydrogen production rate of 6303.5 μmol·g^–1·h^–1 under visible light excitation, which is 2.4 times higher than that of the SCN. Furthermore, the conjecture of the S-scheme mechanism is confirmed by in situ XPS measurement. The 2D/1D S-scheme heterojunction established in this study provides valuable insights into the development of high-efficiency carbon-based catalysts for diverse energy conversion and storage applications.

Emerging two-dimensional (2D) layered metal carbide and nitride materials, commonly termed MXenes, are increasingly recognized for their applications across diverse fields such as energy, environment, and catalysis. In the past few years, MXenes/carbon nanotubes (CNTs)-based hybrids have attracted extensive attention as an important catalyst in energy and environmental fields, due to their superior multifunctions and mechanical stability. This review aims to address the fabrication strategies, the identification of the enhancement mechanisms, and recent progress regarding the design and modification of MXenes/CNTs-based hybrids. A myriad of fabrication techniques have been systematically summarized, including mechanical mixing, spray drying, three-dimensional (3D) printing, self-assembly/in-situ growth, freeze drying, templating, hydrothermal methods, chemical vapor deposition (CVD), and rolling. Importantly, the identification of the enhancement mechanisms was thoroughly discussed from the two dimensions of theoretical simulations and in-situ analysis. Moreover, the recent advancements in profound applications of MXenes/CNTs-based hybrids have also been carefully revealed, including energy storage devices, sensors, water purification systems, and microwave absorption. We also underscore anticipated challenges related to their fabrication, structure, underlying mechanisms, modification approaches, and emergent applications. Consequently, this review offers insights into prospective directions and the future trajectory for these promising hybrids. It is expected that this review can inspire new ideas or provide new research methods for future studies.

Due to their unique properties and uninterrupted breakthrough in a myriad of clean energy-related applications, carbon-based materials have received great interest. However, the low selectivity and poor conductivity are two primary difficulties of traditional carbon-based materials (zero-dimensional (0D)/one-dimensional (1D)/two-dimensional (2D)), enerating inefficient hydrogen production and impeding the future commercialization of carbon-based materials. To improve hydrogen production, attempts are made to enlarge the surface area of porous three-dimensional (3D) carbon-based materials, achieve uniform interconnected porous channels, and enhance their stability, especially under extreme conditions. In this review, the structural advantages and performance improvements of porous carbon nanotubes (CNTs), g-C₃N₄, covalent organic frameworks (COFs), metal-organic frameworks (MOFs), MXenes, and biomass-derived carbon-based materials are firstly summarized, followed by discussing the mechanisms involved and assessing the performance of the main hydrogen production methods. These include, for example, photo/electrocatalytic hydrogen production, release from methanolysis of sodium borohydride, methane decomposition, and pyrolysis-gasification. The role that the active sites of porous carbon-based materials play in promoting charge transport, and enhancing electrical conductivity and stability, in a hydrogen production process is discussed. The current challenges and future directions are also discussed to provide guidelines for the development of next-generation high-efficiency hydrogen 3D porous carbon-based materials prospected.