Seaweed holds significant promise as a renewable feedstock for bioenergy due to its rapid growth, carbon sequestration capacity, and non-competition with terrestrial agriculture. This review examines recent progress in multi-method synergies for optimized energy conversion from seaweed biomass. Physical pre-treatments (e.g., drying, milling, ultrasound, microwave) enhance substrate accessibility but face energy intensity constraints. Chemical processes (acid/alkali, solvent extraction, catalysis) improve lipid/sugar recovery and bio-oil yields, especially via hydrodeoxygenation (HDO) and catalytic cracking over tailored catalysts (e.g., ZSM-5), though cost and byproduct management remain challenges. Biological methods (enzymatic hydrolysis, fermentation) enable eco-friendly valorization but suffer from scalability and enzymatic cost limitations. Critically, integrated approaches—such as microwave-solvent systems or hybrid thermochemical-biological cascades—demonstrate superior efficiency over singular techniques. Upgrading pathways for liquid bio-oil (e.g., HDO, catalytic pyrolysis) show considerable potential for drop-in fuel production, while solid-phase biochar and biogas offer carbon sequestration and circular economy benefits. Future priorities include developing low-cost catalysts, optimizing process economics, and scaling synergies like hydrothermal liquefaction coupled with catalytic upgrading to advance sustainable seaweed biorefineries.

With the growing severity of water pollution, conventional treatment technologies are increasingly unable to satisfy the demand for deep purification. Catalytic wastewater treatment has emerged as an effective strategy for degrading refractory pollutants because of its high efficiency, mild operating conditions, and environmentally friendly nature. This review systematically summarizes recent progress in catalytic materials for wastewater treatment, covering four major categories: metal-based materials, carbon-based materials, multicomponent composites, and photo/electrocatalytic systems. Particular attention is given to their design strategies, structural characteristics, and performance advantages. On this basis, the full mechanistic chain is discussed, from interfacial adsorption and activation to reactive-species generation, including both radical and non-radical pathways, intermediate transformation, and macroscopic reaction kinetics. The review also highlights representative applications in practical wastewater streams, including textile dyeing and pharmaceutical, chemical, landfill leachate, and municipal tailwater treatment, thereby demonstrating the engineering potential of catalytic technologies. At the same time, several critical challenges remain, including insufficient long-term material stability, incomplete mechanistic understanding in complex water matrices, limited adaptability to real wastewater, and the high cost of large-scale preparation. Future research should therefore focus on the development of highly stable, low-cost, and interference-resistant catalytic materials, deeper mechanistic elucidation through in situ characterization and theoretical calculations, stronger integration with membrane separation, biological treatment, photovoltaic or electrochemical processes, and the establishment of standardized evaluation protocols and life-cycle assessment frameworks. These efforts will accelerate the transition of catalytic wastewater treatment toward greener, smarter, and more practical engineering applications.

Conventional thermoelectric conversion and onboard power-generation systems struggle to meet the active-cooling requirements of hypersonic vehicles under extreme conditions. The SCO₂ Brayton cycle emerges as a promising solution due to its high density, specific heat capacity, cost-effectiveness, and superior heat-transfer characteristics. This review analyzes the evolution of SCO₂ Brayton cycle configurations, focusing on the following four primary types: recuperated, compression, combined, and other specialized cycles. Their working principles and processes are summarized. Current application progress is detailed across the following four key areas: cycle layout design, printed circuit heat exchangers, SCO₂ heat-transfer behavior, and operational dynamics. Future research directions for SCO₂-based active cooling in hypersonic applications are identified. Emphasis is placed on understanding SCO₂ flow dynamics within cooling channels during transient vehicle operation and investigating component coupling effects in integrated power-generation systems.

Hydrogen (H₂) is a key clean energy carrier for achieving carbon neutrality, featuring both cleanliness and high efficiency. Biomass-to-hydrogen technologies, with the advantages of strong renewability and low emissions, provide a highly promising alternative to fossil fuel-based hydrogen production. This review summarizes the main pathways and latest research progress in catalytic hydrogen production from biomass, focusing on the role of catalysts and optimization directions in the two major processes of thermochemical and biochemical methods. Despite the rapid development in this field, the large-scale application of biomass-to-hydrogen technologies is still limited by issues such as catalyst deactivation, feedstock composition fluctuations, and low energy efficiency. Traditional biomass-to-hydrogen technologies cannot achieve breakthrough progress in large-scale production in the short term; however, through coupled emerging technologies like biomass electrooxidation for hydrogen production and on-site hydrogen production via aqueous ethanol reforming, biomass-based hydrogen production is expected to solve problems such as low energy efficiency and high transportation difficulties, thereby making an important contribution to the construction of a green and low-carbon hydrogen economy system. Future research should focus on the rational design of stable nanocatalysts, artificial intelligence-driven research and development as well as advanced characterization technologies and the application of integrated systems and process innovation, along with diverse feedstocks and high-value-added product systems.

Thermochemical conversion of nitrogen- and sulfur-rich biomass-derived wastes, such as sewage sludge, algae, and agricultural residues, is a promising route for renewable fuel production and waste valorization. However, fuel-bound nitrogen can be released as NH₃, HCN, and HNCO, while sulfur species such as H₂S, SO₂, and COS accelerate catalyst deactivation and generate NO_x/SO_x precursors. Metal-loaded ZSM-5 catalysts are attractive for clean catalytic pyrolysis because they combine the MFI pore confinement and tunable Brønsted/Lewis acidity of ZSM-5 with the hydrogen transfer, dehydrogenation, cracking, redox, and sulfur-tolerance functions of metal species. This review critically summarizes recent advances in metal-loaded ZSM-5 catalysts for catalytic denitrogenation of biomass-derived solid wastes. The formation and migration of NH₃, HCN, HNCO, tar-N, and char-N are first discussed to clarify the chemical basis of fuel-N conversion. The effects of ZSM-5 pore structure, acid-site distribution, Si/Al ratio, hierarchical porosity, and synergy on adsorption, diffusion, C-N bond cleavage, heterocyclic-N ring-opening, aromatization, and nitrogen redistribution are then analyzed. Catalyst deactivation under realistic pyrolysis atmospheres is also highlighted, including coke deposition, metal sintering, framework dealumination, mineral poisoning, and H₂S/SO₂/COS-induced sulfur poisoning. Finally, future directions are proposed for designing multifunctional ZSM-5-based catalysts integrating denitrogenation activity, sulfur resistance, coke resistance, regenerability, and quantitative nitrogen/sulfur mass balance.