The novel biocomposite based on graphitic carbon nitride (g-C₃N₄ (CN)) and Chitosan (CS) has been deeply studied and summarized in key points concerning various applications. The CN material is composed of the earth-abundant nature of C, N, and H and possesses excellent properties due to its two-dimensional structure, good chemical stability, and a narrow bandgap that allows its use in many applications. There is a lot of information on the role of CN as a potential photocatalyst, but not in association with other composites. In contrast, this minireview summarizes its applications not only in the field of photocatalysis but also in all fields reported on the biocomposite of CN with CS. The incorporation of chitosan helps to overcome the existing limitations of CN, like low-surface area, low light absorption, fast recombination of charges, and hydrophobic character. To introduce, CS is an attractive biomaterial, which is a low-cost alternative for the preparation of films and catalysts due to its unique characteristics such as biodegradability, antimicrobial activity, and film-forming properties that increase the popularity of CN. In this current minireview, a comprehensive study was conducted on the properties, synthesis, and applications along with the advancements of CN incorporated with CS. Finally, we hope to stimulate researchers to study the biocomposite of CN and CS to find new portals and ways to develop effective materials.

The electrocatalytic reduction of nitric oxide and nitrogen dioxide (NOx) remains a significant challenge due to the need for stable, efficient, and cost-effective materials. This study presents a novel support system for NOx reduction in alkaline media, composed of ZrO₂-WO₃-C (ZWC), synthesized via coprecipitation. Platinum nanoparticles (10 wt.%) were loaded onto ZWC and Vulcan carbon support, using similar methods for comparison. Comprehensive physicochemical and electrochemical analyses (N₂ physisorption, XRD, XPS, SEM, TEM, and cyclic and linear voltammetry) revealed that PtZWC outperformed PtC and commercial PtEtek in NOx electrocatalysis. Notably, PtZWC exhibited the highest total electric charge for NOx reduction. At the same time, the hydrogen evolution reaction (HER) was shifted to more negative cathodic potentials, indicating reduced hydrogen coverage and a modified dissociative Tafel mechanism on platinum. Additionally, the combination of WO₃ and ZrO₂ in ZWC enhanced electron transfer and suppressed HER by reducing NO and hydrogen atom adsorption competition. While the incorporation of WO₃ and ZrO₂ lowered the surface area to 96 m²/g, it significantly improved pore properties, facilitating better Pt nanoparticle dispersion (3.06 ± 0.85 nm, as confirmed by SEM and TEM). XRD analysis identified graphite and Pt phases, with monoclinic WO₃ broadening PtZWC peaks (20–25°). At the same time, XPS confirmed oxidation states of Pt, W, and Zr and tungsten-related oxygen vacancies, ensuring chemical stability and enhanced catalytic activity.