Graphitic carbon nitride (g-C₃N₄), as a polymeric semiconductor, is promising for ecological and economical photocatalytic applications because of its suitable electronic structures, together with the low cost, facile preparation, and metal-free feature. By modifying porous g-C₃N₄, its photoelectric behaviors could be facilitated with transport channels for photogenerated carriers, reactive substances, and abundant active sites for redox reactions, thus further improving photocatalytic performance. There are three types of methods to modify the pore structure of g-C₃N₄: hard-template method, soft-template method, and template-free method. Among them, the hard-template method may produce uniform and tunable pores, but requires toxic and environmentally hazardous chemicals to remove the template. In comparison, the soft templates could be removed at high temperatures during the preparation process without any additional steps. However, the soft-template method cannot strictly control the size and morphology of the pores, so prepared samples are not as orderly as the hard-template method. The template-free method does not involve any template, and the pore structure can be formed by designing precursors and exfoliation from bulk g-C₃N₄ (BCN). Without template support, there was no significant improvement in specific surface area (SSA). In this review, we first demonstrate the impact of pore structure on photoelectric performance. We then discuss pore modification methods, emphasizing comparison of their advantages and disadvantages. Each method’s changing trend and development direction is also summarized in combination with the commonly used functional modification methods. Furthermore, we introduce the application prospects of porous g-C₃N₄ in the subsequent studies. Overall, porous g-C₃N₄ as an excellent photocatalyst has a huge development space in photocatalysis in the future.

Graphitic carbon nitride (g-C₃N₄)-based photocatalysts have garnered significant interest as a promising photocatalyst for hydrogen generation under visible light, to address energy and environmental challenges owing to their favorable electronic structure, affordability, and stability. In spite of that, issues such as high charge carrier recombination rates and low quantum efficiency impede its broader application. To overcome these limitations, structural and morphological modification of the g-C₃N₄-based photocatalysts is a novel frontline to improve the photocatalytic performance. Therefore, we briefly summarize the current preparation methods of g-C₃N₄. Importantly, this review highlights recent advancements in crafting high-performance g-C₃N₄-based photocatalysts, focusing on strategies like elemental doping, nanostructure design, bandgap engineering, and heterostructure construction. Notably, sophisticated doping techniques have propelled hydrogen production rates to a 10⁴-fold increase. Ingenious nanostructure designs have expanded the surface area by a factor of 26, concurrently extending the fluorescence lifetime of charge carriers by 50%. Moreover, the strategic assembly of heterojunctions has not only elevated charge carrier separation efficiency but also preserved formidable redox properties, culminating in a dramatic hundredfold surge in hydrogen generation performance. This work provides a reliable and brief overview of the controlled modification engineering of g-C₃N₄-based photocatalyst systems, paving the way for more efficient hydrogen production.

Management of chronic inflammation and wounds has always been a key issue in the pharmaceutical and healthcare sectors. Curcumin (CCM) is an active ingredient extracted from turmeric rhizomes with antioxidant, anti-inflammatory, and antibacterial activities, thus showing significant effectiveness toward wound healing. However, its shortcomings, such as poor water solubility, poor chemical stability, and fast metabolic rate, limit its bioavailability and long-term use. In this context, hydrogels appear to be a versatile matrix for carrying and stabilizing drugs due to their biomimetic structure, soft porous microarchitecture, and favorable biomechanical properties. The drug loading/releasing efficiencies can also be controlled via using highly crystalline and porous metal-organic frameworks (MOFs). Herein, a flexible hydrogel composed of a sodium alginate (SA) matrix and CCM-loaded MOFs was constructed for long-term drug release and antibacterial activity. The morphology and physicochemical properties of composite hydrogels were analyzed by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), ultraviolet-visible spectroscopy (UV-Vis), Raman spectroscopy, and mechanical property tests. The results showed that the composite hydrogel was highly twistable and bendable to comply with human skin mechanically. The as-prepared hydrogel could capture efficient CCM for slow drug release and effectively kill bacteria. Therefore, such composite hydrogel is expected to provide a new management system for chronic wound dressings.

Organic semiconductors (OSCs) have the advantages of tunable molecular structures, suitable band gaps, and exceptional optoelectronic properties. The π-π stacking ability of OSCs also leads to appealing molecular stacking structure, function, and stability. So far, organic photocatalysts have engaged in homogeneous or heterogeneous photocatalysis in the form of free molecules, supported molecules, or nanostructures. Meanwhile, researches on organic photocatalysts have expanded from small organic molecules to the organic macromolecules, as well as their various nanostructures and nanocomposites including isolated zero-dimensional (0D), one-dimensional (1D), two-dimensional (2D), three-dimensional (3D) nanostructures, and their combinations. Therefore, many versatile strategies have been explored to improve photocatalytic ability and practicality either from molecular synthetic modification, crystal, or interface engineering. In this review, we first discuss the photophysical and photochemical processes of organic photocatalysts that govern the ultimate photocatalytic efficiency; we then summarize different forms of organic photocatalysts, their rational design strategies, and mechanistic pathways, as well as their applications in H₂ evolution, CO₂ reduction, and environmental purification, aiming to highlight the structure/property relationships; we lastly propose ongoing directions and challenges for future development of organic photocatalysts in real use.