The continuous rise in atmospheric carbon dioxide (CO2) emissions has prompted the development of carbon utilization technologies. Among the various technologies developed, the catalytic hydrogenation of CO2 into light olefins and C5+ hydrocarbons is one of the most promising pathways for achieving carbon neutrality. Unlike cobalt-based catalysts, which tend to favor methanation, iron (Fe)-based catalysts exhibit unique bifunctionality by effectively coupling the reverse water gas shift (RWGS) and Fischer-Tropsch synthesis (FTS) reactions. This dual function of Fe-based catalysts is driven by the dynamic active-phase evolution between iron oxide (Fe3O4) and carbide (Fe5C2), which is essential for balancing CO activation with chain propagation. However, water-induced active site oxidation and catalyst sintering leads to the deactivation of Fe-based catalysts due to active site loss. This review summarizes the recent developments in Fe-based catalytic FTS reactions and elucidates the structure-performance relationships that control the overall product selectivity. Furthermore, it suggests future perspectives for overcoming and bridging the gap between the laboratory and the industries by focusing on green hydrogen integration and operando characterization to advance practical CO2 valorization techniques.

This paper provides a comprehensive overview of the recent research trends in the electrochemical nitrate reduction reaction (NO3RR) as an environmentally sustainable route for ammonia synthesis. The conventional Haber-Bosch process suffers from intrinsic limitations, including high-temperature and high-pressure operation requirements and reliance on fossil-fuel-derived hydrogen, resulting in substantial CO2 emissions. Consequently, the development of alternative ammonia production technologies compatible with carbon neutrality has become imperative. NO3RR offers both environmental remediation and resource recovery benefits by removing nitrate, a major contaminant in aquatic environments, while simultaneously producing NH3. This review first examines the historical development and current status of the Haber-Bosch process, followed by an analysis of NO3RR as a carbon-reducing and environmentally benign ammonia production pathway. The multi-electron transfer mechanism of nitrate reduction is summarized and the key processes governing the reaction selectivity and kinetics are the NO3– → NO2– initial activation step and the NH2OH → NH3 final hydrogenation step. Subsequently, catalytic systems based on noble metals are compared, focusing on how surface structure, defect engineering, and alloying strategies achieve high Faradaic efficiency and NH3 selectivity. Non-noble metal catalysts are also discussed, emphasizing cost-effective yet high-performance design principles such as interfacial electronic modulation, oxygen vacancy engineering, single-atom catalytic sites, and synergistic alloy effects. Overall, this paper suggests that NO3RR-based electrochemical ammonia synthesis could potentially complement or even replace the Haber-Bosch process. Lastly, future directions in catalyst design and the practical applicability of NO3RR for wastewater treatment are proposed.

To mitigate the accelerating impacts of climate change, extensive research efforts have focused on reducing CO2 emissions and converting CO2 into value-added chemicals. Among the various strategies, the electrocatalytic reduction of CO2 (CO2RR) shows great potential for carbon recycling and renewable energy storage, particularly when coupled with intermittent renewable power sources. In this study, a high-pressure CO2RR system was developed to enhance the local CO2 concentration and suppress the competing hydrogen evolution reaction (HER) in order to enable selective electroreduction of CO2 to CO. The NiO/CNT composite catalyst exhibited superior catalytic performance compared to bare Ni or NiO, achieving a Faradaic efficiency (FECO) exceeding 75.1% at –3.0 V and 6.0 MPa. The synergistic combination of NiO and carbon nanotubes enhanced CO2 adsorption, charge transfer, and intermediate stabilization. This resulted in an improved CO selectivity under elevated pressures. The applied high-pressure conditions further promoted CO2 solubility and interfacial mass transport, while diminishing HER activity. This work provides new mechanistic insights into pressure-dependent CO2 reduction and highlights the critical role of the local microenvironment in determining product selectivity. The findings of this study establish a rational design framework for optimizing CO2RR systems by integrating pressure modulation with conductive composite catalysts in order to develop efficient and durable electrochemical CO2-to-CO conversion technologies.

Biomass-derived 2,5-dimethylfuran was employed as a renewable feedstock to investigate the structure-performance relationship of zirconium- and chromium-based metal-organic frameworks (MOFs) for the production of p-xylene. Three frameworks, UiO-66(Zr), MOF-808(Zr), and MIL-101(Cr), were synthesized to evaluate how pore structures affect reactivity and selectivity, and to confirm that framework openness governs diffusion and intermediate stability. The sulfonic acid functionalization of UiO-66(Zr) and MIL-101(Cr) promoted dehydration and aromatization and enhanced the catalytic performance by strengthening the Brønsted acidity. Notably, the sulfonated MOFs exhibited strong Lewis-Brønsted synergy, resulting in a significantly improved p-xylene yield. This study shows that pore and acidity modulation are viable strategies for MOF catalyst design.

A key strategy to enhance the performance of perovskite solar cells (PSCs) is the fabrication of high-quality perovskite active layers with uniform morphology and large grain domains in order to reduce defect density and improve charge transport. Inkjet printing presents great potential for scalable PSC fabrication due to its non-contact patterning, minimal material consumption, and compatibility with large-area and flexible substrates. Nevertheless, obtaining uniform and high-quality perovskite films through inkjet printing remains challenging, as it demands sophisticated control over ink formulation and crystallization kinetics. In this work, a facile solvent engineering approach is proposed for the development of inkjet-printable perovskite inks with tailored rheological properties. By introducing high-viscosity co-solvents, the solvent composition was optimized to stabilize droplet jetting and modulate crystal nucleation dynamics. The controlled evaporation rate and delayed crystallization facilitated the growth of large and uniform grains with superior surface coverage. Comprehensive characterization using atomic force microscopy (AFM), scanning electron microscopy (SEM), and X-ray diffraction (XRD) revealed that the optimized ink formulation produced perovskite films with an average surface roughness reduced by up to 75.6% and improved crystallinity compared to conventional formulations. This simplified solvent engineering strategy, relying solely on ink compositional tuning, offers an efficient pathway toward the scalable production and commercialization of high-performance, inkjet-printed PSCs.

A dissolution-precipitation recycling process was developed to recover high-quality polyamide, particularly PA66, from silicone-coated automotive airbag waste. Solvent screening based on Hansen solubility parameters (HSP) identified formic acid as an effective solvent and methanol as a suitable antisolvent. Optimal processing conditions were established by adjusting key variables including solution concentration, solvent concentration, dissolution temperature, and dissolution time. The process achieved a recovery yield exceeding 90% under mild conditions (≤ 20 w/v%, room temperature, 1 h). Thermal characterization using TGA and DSC confirmed that no silicone residues remained in the recovered polymer and that the thermal decomposition and melting behavior exhibited minimal changes compared to the virgin material. XPS analysis demonstrated the complete removal of Si-based coatings and the retention of nitrogen-containing amide bonds, indicating preservation of the polymer’s chemical purity. ATR-FTIR spectra revealed no shifts in characteristic polyamide functional groups, confirming that the polymer backbone was not degraded during solvent exposure. Furthermore, GPC analysis showed that the recovered polymer maintained or slightly increased its Mw values and exhibited stable retention times, indicating negligible chain scission and a molecular weight distribution compatible with practical reuse. These results collectively verify that the proposed dissolution-precipitation process enables the high-purity recovery of PA66 without compromising its structural integrity, even from complex silicone-coated composite waste streams. The process demonstrates strong industrial potential for the upcycling of end-of-life automotive polymer components toward resource-circulating manufacturing.

This study presents a pilot-scale demonstration of a cryogenic distillation process for producing high-purity liquid CO2 from flue gas. A process simulation model was developed to analyze the behavior of a pilot plant operating at 35 bar by using Aspen Plus® with the Peng-Robinson equation of state. However, conventional equilibrium-based models exhibit limitations in accurately describing the partial condensation behavior observed in the pilot system. To address this, a modified modeling approach was proposed by incorporating finite heat removal in the condenser, followed by a pressure-enthalpy flash calculation. This approach accounts for the non-equilibrium nature of condensation, where the effective condensation temperature is governed by heat transfer conditions rather than the bulk vapor equilibrium. The revised model showed good agreement with the pilot-scale data, accurately reproducing the off-gas composition and CO2 purity, and predicting an off-gas flow rate of approximately 174 kg/h. Furthermore, the experimental results showed that adopting a partial condensation strategy at a bulk vapor temperature of –21.4oC, instead of the theoretical vapor liquid equilibrium temperature of –56 oC, is a robust method for achieving liquid CO2 with a purity of 96% while mitigating the risk of dry ice formation. These findings provide practical operation guidelines for the design and scalability of commercial CO2 liquefaction processes.

Alginate is a polysaccharide derived from seaweed that can bind with a variety of metal ions. It is a promising eco-friendly adsorbent for the removal of heavy metals from aqueous solutions. In this study, gel and dry beads were prepared by cross-linking alginates with different molecular weights using various metal ions (Cu2+, Ca2+, Ba2+). The physicochemical properties of the prepared samples were characterized by field-emission scanning electron microscopy (FESEM), Fourier-transform infrared spectroscopy (FTIR), and Brunauer-Emmett-Teller (BET). The lead removal performance of the samples was evaluated in an aqueous solution containing 1,000 ppm of lead (Pb2+) for 24 h. The results showed that the lead removal performance of the Ca2+ sample was the highest followed by the Cu2+ and Ba2+ samples. In contrast, no significant differences were observed according to the molecular weight of the alginate. The lead removal efficiency was closely related to the specific surface area of the metal-alginate composites, indicating that a high surface area is a critical parameter for lead removal. This work demonstrates that alginate derived beads are highly effective adsorbents for the removal of lead from aqueous solutions, and that their performance can be optimized by controlling the type of metal ions used for crosslinking.

The overall performance of Fe-based catalysts in the direct hydrogenation of CO2 to long-chain hydrocarbons (C5+) is strongly influenced by the nature and electronic properties of metal oxide promoters. This study investigates the effect of calcination temperature on Na-promoted Fe-ZrOx (FZOₓ-y) catalysts synthesized via co-precipitation and thermally treated at temperatures between 400 and 900 oC. The catalyst calcined at 600oC (FZOx-600) exhibited the highest activity, achieving a CO2 conversion of 44.0% and an unprecedented C5+ yield of 23.0% at 330oC, 3.5 MPa, an H2/CO2 ratio of 3:1, and a gas hourly space velocity of 4,000mL g–1 h–1. The partial reduction of ZrO2 enhances CO2 adsorption and activation by forming ZrOx species that donate electrons to Fe. The resulting Fe3O4/ χ-Fe5C2 dual phases drive the reverse water-gas shift and Fischer-Tropsch reactions, promoting long-chain hydrocarbon formation. These findings demonstrate that calcination-induced electronic modulation of the Fe-Zr interface enables superior CO2 hydrogenation activity and offer a new strategy for designing efficient catalysts for the direct production of liquid fuels and high-value hydrocarbons.