Xiaojuan Bai

Suppressing ultrafast charge recombination remains a central challenge in semiconductor photocatalysis. Herein, we report a cross-conjugation-driven charge concentration polarization strategy for promoting charge separation in imide-linked porous organic polymers. Two polymers with distinct conjugation topologies, TAPB–PMDA and TAPB–HPMDA, were constructed as model systems to elucidate the relationship between conjugation structure and charge migration behavior. Compared with the TAPB–HPMDA, the cross-conjugated TAPB–PMDA induces asymmetric electron delocalization and establishes a spatial gradient of photogenerated electron density within the polymer framework, which enables efficient charge separation. The locally high electron concentration microenvironment, regulated by charge gradient polarization, activates the CO bonds, significantly optimizing O₂ adsorption and activation while stabilizing the ·OOH intermediate. Consequently, this material exhibits a highly selective two-electron oxygen reduction to H₂O₂ reaction, achieving a yield of 2440.74 μmol g⁻¹ h⁻¹ in pure water along with improved photocatalytic degradation of antibiotics, including rapid removal and significant mineralization of ciprofloxacin. After adding benzyl alcohol as a sacrificial agent, the yield was further increased to 16 350 μmol g⁻¹ h⁻¹. This work provides mechanistic insight into how molecular polarization in porous organic frameworks influences reactive oxygen species generation, offering a design strategy for developing efficient organic photocatalysts for sustainable water purification.

The oxygen-enriched and electron-enriched microenvironment effectively promoted the efficient migration, enabling stable H ₂ O ₂ generation and photocatalytic degradation of SMX.

Graphite carbon nitride has garnered significant research interest for photocatalytic pollutant degradation. However, the slow kinetics of the oxygen reduction reaction and the high recombination rate of photogenerated charges have hindered improvements in its performance. This paper synthesizes etched and crushed carbon nitride by introducing sulfonyl groups into it. Comprehensive experimental characterization and theoretical calculation show that the sulfonyl group optimizes the electronic structure of the catalyst and promotes the separation and migration of photogenerated charges. More importantly, the sulfonyl group is directly anchored at the hydrophobic interface, reducing the reaction energy barrier while promoting the photocatalytic self‐Fenton efficiency. In addition, the modified catalyst achieved a maximum H ₂ O ₂ yield of 1571.63 µmol g ⁻¹ h ⁻¹ , with a high apparent quantum efficiency of 11.37% at 380nm and a solar‐to‐chemical energy conversion efficiency of 0.81%. Ciprofloxacin was degraded into non‐toxic small molecules within 30 min, and the degradation kinetic efficiency was increased by 6.04 times. The photocatalytic performance has been significantly improved. This study provides a significant strategy for adjusting the structure of photocatalysts by introducing electron‐withdrawing groups and directionally anchoring them at hydrophobic interface to enhance catalytic activity and also provides valuable insights for the design and development of highly efficient photocatalysts.

Novel Lewis acid sites: efficient charge separation enables H ₂ O ₂ production, activation, and antibiotic degradation.

Competition and regulation of iron-based activated peroxyacetic acid radicals with non-radicals.

To combat antibiotic pollution in aquatic systems, this work designed dimension‐controlled porous organic polymers (POPs) with ordered porosity via a molecular‐dimensional control strategy. The 2D POP utilizes highly planar triazine groups as electron acceptors, which are linked to thiophene electron donors via imine bonds to form a donor‐acceptor structure. The strong coplanarity of triazine groups significantly enlarges molecular dihedral angles, facilitating ordered π–π stacked lamellar architecture with enhanced interlayer conjugation. In contrast, the 3D POP constructed with methane as the central unit has reduced coplanarity and electronic coupling due to steric hindrance. Comparative studies are shown that the planar layered structure of the 2D POP effectively promotes exciton dissociation (with an exciton binding energy of only 2.01 eV), achieving continuous electron supply and stable catalytic performance. The 3D POP achieves continuous H ₂ O ₂ production at 1672 µmol g ⁻¹ h ⁻¹ under sacrificial agent‐free conditions, enabling efficient degradation of ibuprofen via the photo‐self‐Fenton process and increasing the degradation rate constant to 0.034 min ⁻¹ . This work elucidates the structural superiority of 2D donor‐acceptor‐type POPs in photocatalytic systems from the perspective of spatial configuration regulation of molecular building blocks, providing insights for designing advanced water‐treatment materials.

Hydrogen-bonded hierarchical porous POPs enable the promotion of oxygen mass transfer for photocatalytic H ₂ O ₂ production.

Review Xiaojuan Bai ^1,2,*, Yihan Cao ¹, Bowen Zhu ¹, Rujiao Liu ¹, Jiaqian Dong ¹, and Hua Yang ^{1 1} Key Laboratory of Urban Stormwater System and Water Environment, Ministry of Education, Beijing University of Civil Engineering and Architecture, Beijing 100044, China ² Beijing Energy Conservation & Sustainable Urban and Rural Development Provincial and Ministry Co-construction Collaboration Innovation Center, Beijing University of Civil Engineering and Architecture, Beijing 100044, China * Correspondence: baixiaojuan@bucea.edu.cn Received: 8 June 2024; Revised: 8 August 2024; Accepted: 20 August 2024; Published: 20 September 2024 Abstract: The increasing prevalence of antibiotic-resistant infections globally emphasizes the urgent need for effective antimicrobial strategies. Photocatalysts, known for their efficiency, broad-spectrum activity, and environmental benefits, present a promising alternative. With the development of natural solar light driven photocatalysts, the antimicrobial and bactericidal range has been further extended. Photocatalytic materials can be activated by various light wavelengths to generate reactive oxygen species (ROS), which can effectively eliminate a wide range of pathogenic microorganisms including bacteria, fungi, and protozoa. However, the limited optical response range, suboptimal bandgap, and slow electron cycling limit the efficient generation of ROS, resulting in lower sterilization efficiency of photocatalytic antimicrobials. Additionally, the short half-life and limited migration distance of ROS restrict their antimicrobial activity. This review focuses on the process and mechanism of ROS generation in photocatalytic reactions, and highlighting the recent advances in the typical photocatalysts. We also explore strategies to enhance ROS diffusion and utilization, including morphology control, noble metal deposition, doping, co-catalyst loading, vacancy introduction, surface functionalization, and heterojunction construction. These strategies aim to increase the efficiency of ROS generation and prolong their activity, thereby enhancing the overall antimicrobial effectiveness. Thereafter, the review presents state-of-the-art applications of photocatalysts in water purification, medical coatings, and air disinfection. Furthermore, it explores key challenges and opportunities that may drive future innovations and advancements in photocatalytic antimicrobial applications, aiming to develop more effective and sustainable solutions.

Covalent organic frameworks (COFs) have shown significant advancements in the realm of photocatalytic hydrogen peroxide (H₂O₂) production, attributed to their exceptional crystallinity, ordered porosity, abundance of active sites, pre-designed functional groups, and outstanding stability. This review delves into the impact of COFs' crystallinity on their photocatalytic efficacy, particularly in H₂O₂ generation, it systematically summarizes the structural benefits and research advancements in H₂O₂ production using these long-range ordered crystalline COFs, focusing on enhancing visible light absorption, optimizing charge separation and migration, improving material stability, and providing active sites. Additionally, the strategies to enhance COFs' crystallinity through optimization of polymerization reaction conditions and precise modulation of intermolecular interactions are discussed. Furthermore, various modulation techniques to enhance H₂O₂ efficiency are explored. By elucidating the relationship between COFs' crystallinity and photocatalytic H₂O₂ production, this review not only enhances the comprehension of the structure–property correlation of COFs but also offers valuable guidance and a scientific foundation for the development of highly efficient and innovative crystalline COFs for H₂O₂ applications.

Article Improvement of Extraction Efficiency and Metabolites of Pollutants from Medium and Low Concentration Organic Polluted Soil Xiaojuan Bai 1,2,*, Wei Song 2, Linlong Guo 2, Rujiao Liu 2, Yihan Cao 2, Pin Jin 2, Bowen Zhu 1,2 and Xiaoran Zhang 1,2 1 Centre for Urban Environmental Remediation, Beijing University of Civil Engineering and Architecture, Beijing 100044, China 2 Beijing Energy Conservation & Sustainable Urban and Rural Development Provincial and Ministry Co-Construction Collaboration Innovation Center, Beijing University of Civil Engineering and Architecture, Beijing 100044, China * Correspondence: baixiaojuan@bucea.edu.cn or heixia.1986@163.com Received: 6 February 2024; Revised: 11 March 2024; Accepted: 8 April 2024; Published: 15 April 2024 Industrial development has accelerated soil contamination by organic pollutants, posing a major threat to global ecosystems and human health. Natural attenuation techniques, renowned for their environmental compatibility and cost-effectiveness, have garnered widespread attention for the remediation of environmental pollution. In this work, we have successfully enhanced the natural attenuation process of organic contaminants in soil by employing biostimulation and bioaugmentation methods to remove pollutants. The results showed that the degradation rate of low molecular weight polycyclic aromatic hydrocarbons (PAHs) reached about 82.5% while medium molecular weight PAHs was about 43.72%, as well as high molecular weight PAHs was about 34.5% even after a remediation process of only 14 days. In addition, the biofortified soil was exhaustively analyzed by high-throughput sequencing, which showed that the dosing of bactericide and surfactants significantly increased the abundance of 16sRNA genes and alkane degradation-related genes. In response to the challenges of detecting and analyzing complex organic pollutants in soil, we have developed an integrated method for the extraction, purification, and detection of organic pollutants in soil, ranging from low to medium concentrations. This approach not only allows for the efficient extraction of organic pollutants from the soil but also facilitates further inference of the degradation mechanisms of these pollutants. Integrating chemical analysis and microbiological techniques, and employing Gas Chromatography-Mass Spectrometry (GC-MS) and High-Resolution Mass Spectrometry (HRMS), we precisely measured and identified organic contaminants in soil and deduced the mechanisms of degradation. These findings are significant for the development of new environmental remediation technologies and strategies, contributing to addressing soil pollution issues exacerbated by industrial activities.