Photocatalytic CO2 reduction using H2O as the electron donor offers a sustainable pathway for carbon–neutral fuel synthesis; however, its efficiency is limited by sluggish charge separation and insufficient CO2 activation. Herein, we develop a ruthenium-decorated, fluorine-doped TiO2 photocatalyst (Ru/F-TiO2) that overcomes these limitations through spatially directed charge modulation and cooperative electronic engineering. Fluorine doping introduces oxygen vacancies that narrow the bandgap and form surface Ti‒F bonds, suppressing charge recombination. Simultaneously, Ru nanoparticles serve as efficient CO2 adsorption and activation centers while introducing additional surface defects that further strengthen CO2 binding. The strong coupling between Ru and semiconductor forms a Schottky junction, establishing a strong built-in electric field that promotes directional electron migration toward Ru sites and hole accumulation on F-TiO2. Consequently, Ru/F-TiO2 exhibits outstanding activity and durability, delivering CO and CH4 production rates of 124.8 and 19.8 μmol/(g·h), respectively. In situ diffuse reflectance infrared Fourier-transform spectroscopy analysis reveals key proton-coupled, multi-electron intermediates, elucidating the reaction pathway. This study demonstrates that the synergistic integration of non-metal doping and metal cocatalyst engineering provides a powerful strategy to regulate charge dynamics and boost solar-driven CO2 conversion.
Photocatalytic C–N coupling reactions using waste plastic- and biomass-based feedstocks with nitrogen-containing species have emerged as a promising route for the synthesis of high-value chemicals such as amides and amino acids. However, the complexity of multistep reaction routes and the presence of competing side reactions pose significant challenges, often leading to low yield and poor selectivity of target products. To substantially enhance the efficiency and selectivity of C–N coupling reactions, it is imperative to gain a thorough understanding of the underlying reaction mechanisms and to develop highly active photocatalysts. Such catalysts must be capable of effectively activating diverse substrates while maintaining an appropriate balance between the adsorption and desorption of carbon- and nitrogen-containing intermediates or radical species. In this review, we systematically summarize recent advances in photocatalytic C–N coupling for the production of amides and amino acids from waste plastic- and biomass-based feedstocks, with particular focus on catalyst selection, process design, control of reaction intermediates, and catalytic mechanisms. Furthermore, the technoeconomic feasibility and environmental impact of these C–N coupling reactions are evaluated using technoeconomic analysis and life-cycle assessment. Lastly, the current challenges and future prospects in this field are also discussed. This review aims to provide valuable insights for the development of high-efficiency photocatalytic C–N coupling reactions and to deepen the understanding of their catalytic mechanisms.
Immobilized microalgae technologies (IMTs) involve the fixing of free-living microalgae onto specialized carriers through physical adsorption, chemical cross-linking, or biological interactions to enhance cell retention, metabolic stability, and stress resistance. These have emerged as multifunctional and sustainable platforms for environmental remediation, extending their applications beyond wastewater treatment to include soil and air purification. This review categorizes advanced IMT carriers into three major types: (1) inorganic engineered materials (e.g., biochar–nanoparticle hybrids), (2) functionalized organic polymers (e.g., pH-responsive hydrogels), and (3) bio-derived scaffolds (e.g., fungal–algal and algal–bacterial consortia). They enhance microalgal retention, metabolic activity, and microalgal stress resistance, enabling the effective removal of nitrogen, phosphorus, heavy metals, organic pollutants, and airborne particulates across diverse environmental matrices. We highlight key cooperative mechanisms—such as extracellular polymeric substance (EPS)-mediated adhesion, quorum sensing, and metabolic synergy—that underpin pollutant removal and biomass stability. Particular emphasis is placed on integrating smart technologies, including magnetic microrobots, 3D/4D-printed scaffolds, and AI-guided optimization, which improve the scalability, adaptability, and environmental responsiveness of IMT systems. By synthesizing the advances in materials science, microbial ecology, and environmental engineering, this review defines the future direction of research into IMTs as a next-generation bioengineering strategy for the integrated management of water, soil, and air pollution.
Photocatalysis—a green and energy-efficient technology for environmental remediation and energy conversion—has recently demonstrated broad application potential in intelligent building materials. This review systematically summarizes recent advancements in incorporating photocatalytic materials into building applications, focusing on two main scenarios: pavement and wall surfaces. In pavement systems, photocatalytic materials are primarily employed to degrade pollutants such as NOx and volatile organic compounds, thereby actively reducing emissions. In wall applications, the emphasis is on imparting intelligent maintenance functions, including self-cleaning, antibacterial activity, and air purification. We provide a comprehensive analysis of the performance of various photocatalytic materials, their incorporation methods, and their effects on mechanical properties and environmental durability. Building on this analysis, we propose design principles for photocatalytic building materials that balance catalytic efficiency with cost, enhance mechanical stability, and preserve the intrinsic functions of building components. Finally, we outline future research directions, emphasizing the significant potential of photocatalytic building materials in advancing green construction and sustainable development.
Fluorinated carbon is a prospective cathode material for lithium (Li) primary batteries, which are widely used as power sources for military applications, such as individual combat, spacecraft, and deep-sea detection. It offers high gram-specific capacity but is hindered by its low intrinsic conductivity and large volume expansion. However, fluorinated Ketjen black (FKB), with enhanced conductivity and less volume expansion compared with other fluorinated analogs, has been the subject of extensive attention, with its discharge mechanism being unclear. Herein, the structural evolution and compositional changes of FKB at various depths of discharge are revealed through characterization and analysis: The three-dimensional (3D), chain-like aggregate structure of FKB has a high void ratio, which can provide a storage space for LiF formation, thereby inhibiting the volume deformation during discharge. The discharge reaction model is a synergistic mechanism of a surface uniform reaction and local structural reorganization. The surface and defect sites preferentially react with Li+ and the C–F bonds in the 3D, chain-like structure selectively break to form LiF. We anticipate that our study paves the way for implementing better Li/fluorinated carbon (Li/CFx) batteries.
With increasing global energy demand and growing concerns over climate change, methods for catalytic reduction of CO2 have been extensively studied, among which graphitic carbon nitride (g-C3N4) attracts remarkable attention due to its easily available raw materials and outstanding chemical stability. However, its wide bandgap and low photon usage efficiency limit its application in photocatalysis. Doping g-C3N4 to introduce active sites can enhance its catalytic performance. Herein, asymmetric phosphorus–cobalt dual sites were introduced onto g-C3N4 via hydrothermal treatment and thermal polymerization. P (phosphorus) could enhance CO2 adsorption, while Co (cobalt) functions as a metallic site to boost the separation rate of photogenerated carriers. A photocatalytic CO2 reduction to CO with a rate of 93.2 μmol/(g·h) was achieved, which was two times that of g-C3N4. During stability testing, ethylene with a formation rate of approximately 2 μmol/(g·h) was observed, as well as trace quantities of methanol and acetic acid in the liquid products. This work shows a promising strategy by the introduction of asymmetric phosphorous–cobalt dual sites for efficient photocatalytic conversion of CO2 to CO and C2 products.