Current Issue

2025, Volume 10,  Issue 6

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Review articles
Abstract:
Carbon dioxide accounts for about 80 percent of greenhouse emissions and the increasing CO2 emission has been identified as a critical environmental issue. On the other hand, CO2 is a potentially renewable resource of a single carbon molecule, and new technologies to utilize CO2 in producing net-zero fuels and chemicals are of global interest. Great efforts have been made in the development of new materials and processes for CO2 capture and utilization (CCU). Among them, ionic liquids (ILs) have attracted much attention due to their unique characteristics such as high CO2 solubility, high ionic conductivity, negligible volatility, non-flammability, wide electrochemical window, and high thermal stability, as well as good solvation ability. This review summarizes the most recent efforts devoted to IL-based absorption, catalysts, and CO2 capture and utilization processes. We discuss the factors that affect the interaction between ILs and CO2, impacting on the viscosity and CO2 solubility and preview the coupling of CO2 capture with electrochemical conversion of CO2. Finally, we provide an overview on the advantages and disadvantages of the IL-based process for practical applications.
Abstract:
Hydrogen evolution reaction (HER) plays a crucial role in developing clean and renewable hydrogen energy technologies. However, conventional HER catalysts rely on expensive and scarce noble metals, which is a significant challenge for practical application. Recently, two-dimensional transition metal dichalcogenides (2D-TMDs) have emerged as attractive and cost-effective alternatives for efficient electrocatalysis in the HER. Substantial efforts have been dedicated to advancing the synthesis and application of 2D-TMDs. This review highlights the design and synthesis of high-performance 2D-TMDs-based HER electrocatalysts by combining theoretical calculations with experimental methods. Subsequently, recent advances in synthesizing different types of 2D TMDs with enhanced HER activity are summarized. Finally, the conclusion and perspectives of the 2D TMDs-based HER electrocatalysts are discussed. We expect that this review will provide new insights into the design and development of highly efficient 2D TMDs-based HER electrocatalysts for industrial applications.
Abstract:
The valorization of biomass to produce biofuels has become a heavily investigated field due to the depletion of fossil fuels and environmental concerns. Among them, the research on deoxygenation of fatty acids or esters derived from biomass as well as municipal sludge organics to produce diesel-like hydrocarbons has become a hot topic. Fatty acid is a key intermediate derived from ester hydrolysis, therefore has attracted more attention as a model compound. In this review, we first introduce and compare the three reaction pathways of hydrodeoxygenation, decarboxylation and decarbonylation, for the deoxygenation of fatty acids and esters. The preference of reaction pathway is closely related to the type of raw materials and catalysts as well as reaction conditions. The special purpose of this review is to summarize the dilemma and possible strategies for deoxygenation of fatty acids, which is expected to provide guidance for future exploration and concentrates. The atom utilization along with stability during reaction in a long time is the most important index for commercial economy. Herein, we propose that the rational design and delicate synthesis of stable single-atom non-noble catalysts may be the best solution. The ultimately goal is aiming to develop sustainable production of green diesel hydrocarbons.
Abstract:
Researchers have recently developed various surface engineering approaches to modify environmental catalysts and improve their catalytic activity. Defect engineering has proved to be one of the most promising modification methods. Constructing defects on the surface of catalytic materials can effectively modulate the coordination environment of the active sites, affecting and changing the electrons, geometry, and other important properties at the catalytic active sites, thus altering the catalytic activity of the catalysts. However, the conformational relationship between defects and catalytic activity remains to be clarified. This dissertation focuses on an overview of recent advances in defect engineering in environmental catalysis. Based on defining the classification of defects in catalytic materials, defect construction methods, and characterization techniques are summarized and discussed. Focusing on an overview of the characteristics of the role of defects in electrocatalytic, photocatalytic, and thermal catalytic reactions and the mechanism of catalytic reactions. An elaborate link is given between the reaction activity and the structure of catalyst defects. Finally, the existing challenges and possible future directions for the application of defect engineering in environmental catalysis are discussed, which are expected to guide the design and development of efficient environmental catalysts and mechanism studies.
Abstract:
Sustainable aviation fuel (SAF) production from biomass and biowaste streams is an attractive option for decarbonizing the aviation sector, one of the most-difficult-to-electrify transportation sectors. Despite ongoing commercialization efforts using ASTM-certified pathways (e.g., lipid conversion, Fischer-Tropsch synthesis), production capacities are still inadequate due to limited feedstock supply and high production costs. New conversion technologies that utilize lignocellulosic feedstocks are needed to meet these challenges and satisfy the rapidly growing market. Combining bio- and chemo-catalytic approaches can leverage advantages from both methods, i.e., high product selectivity via biological conversion, and the capability to build C-C chains more efficiently via chemical catalysis. Herein, conversion routes, catalysis, and processes for such pathways are discussed, while key challenges and meaningful R&D opportunities are identified to guide future research activities in the space. Bio- and chemo-catalytic conversion primarily utilize the carbohydrate fraction of lignocellulose, leaving lignin as a waste product. This makes lignin conversion to SAF critical in order to utilize whole biomass, thereby lowering overall production costs while maximizing carbon efficiencies. Thus, lignin valorization strategies are also reviewed herein with vital research areas identified, such as facile lignin depolymerization approaches, highly integrated conversion systems, novel process configurations, and catalysts for the selective cleavage of aryl C-O bonds. The potential efficiency improvements available via integrated conversion steps, such as combined biological and chemo-catalytic routes, along with the use of different parallel pathways, are identified as key to producing all components of a cost-effective, 100% SAF.
Research papers
Abstract:
Porous materials are excellent adsorbents for the removal of organic dyes from sewage and play a significant role in environmental restoration. Herein, two ferrocene (Fc)-based covalent organic frameworks (Fc-COFs), namely FcTF-COF and FcBD-COF, are successfully synthesized for the first time through a solvothermal method, and the obtained Fc-COFs powders are used to adsorb Congo red (CR) from water. The results show that both FcTF-COF and FcBD-COF have superb adsorption performance towards CR with ultrahigh adsorption capability of 1672.2 mg g-1 and 1983.7 mg g-1 at pH = 4.0, respectively, outperforming the majority of the reported solid porous adsorbents. The maximum adsorption of both Fc-COFs agrees with the Sips adsorption isothermal model, indicating that their adsorption was dominated by heterogeneous adsorption. The Coulombic interactions, hydrogen bonding, π-π interactions and ion-dipolar interactions should all contribute to their ultrahigh CR adsorption capability and high-pH resistance performance regardless of the pH in the range of 4-9. In addition, after five cycles, both COFs still remain their exceptional high CR adsorption capabilities. This study offers a prospective organic porous adsorbent with promising applications for organic dye removal in sewage processing.
Abstract:
Noble metal-loaded layered hydroxides exhibit high efficiency in electrocatalyzing water splitting. However, their widespread use as bifunctional electrocatalysts is hindered by low metal loading, inefficient yield, and complex synthesis processes. In this work, platinum atoms were anchored onto nickel-iron layered double hydroxide/carbon nanotube (LDH/CNT) hybrid electrocatalysts by using a straightforward milling technique with K2PtCl6·6H2O as the Pt source. By adjusting the Pt-to-Fe ratio to 1/2 and 1/10, excellent electrocatalysts—Pt1/6-Ni2/3Fe1/3-LDH/CNT and Pt1/30-Ni2/3Fe1/3-LDH/CNT—were achieved with superior performance in hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), outperforming the corresponding commercial Pt/C (20 wt%) and RuO2 electrocatalysts. The enhanced electrochemical performance is attributed to the modification of Pt's electronic structure, which exhibits electron-rich states for HER and electron-deficient states for OER, significantly boosting Pt's electrochemical activity. Furthermore, the simple milling technology for controlling Pt loading offers a promising approach for scaling up the production of electrocatalysts.
Abstract:
Hierarchical lignin-derived ordered mesoporous carbon (HOMC) was significant for advanced supercapacitors. However, achieving controllable fabrication and optimizing electrochemical behavior were challenging. In this work, an eco-friendly HOMC was synthesized using lignin as carbon precursors and Zn2+ as cross-linking and pore-forming agents, followed by KHCO3 activation, eliminating the need for toxic phenolic resins and acid treatments for metal removal. Machine learning technology, specifically an Artificial Neural Network (ANN) model, was utilized to assist the experimental design and prediction. The ANN model suggested an ideal hierarchical structure and optimized oxygen level, achieved through the adjustment of Zn2+ additive concentration, carbonization temperature, and subsequent KHCO3 activation to maximize capacitance. The HOMC electrode, with a micropore-to-mesopore ratio (Smicro/Smeso) of 1.01 and an oxygen content of 8.81 at%, acquired a specific capacitance of 362 F·g-1 at 0.5 A·g-1 in 6 mol·L-1 KOH electrolyte. The assembled HOMC//HOMC supercapacitor could afford a high energy density of 33.38 Wh·kg-1 with a corresponding specific power density of 300 W·kg-1 in TEATFB/PC electrolyte. Meanwhile, the long-term cycle stability of 94.33% was achieved after 20,000 cycles. This work provides an ANN-assisted strategy for the synthesis of HOMC, highlighting its potential to valorize biomass and agricultural waste in sustainable energy storage solutions.
Abstract:
Rational design of porous metal oxide films that serve as not only the scaffolds for light absorbers but also the transfer layer of photogenerated charges is essential for fabricating highly efficient photoanodes for photoelectrochemical (PEC) hydrogen generation. In this work, we report a facile one-step pyrolysis method which can convert Zn-based MOF to porous ZnO (m-ZnO) with rough surface and abundant oxygen vacancies (Ov). When incorporating core-shell quantum dots (QDs) as the light absorbers, the obtained photoanodes (m-ZnO@QDs) achieved outstanding PEC performance for hydrogen generation, exhibiting 1.6 times and 5.8 times higher saturated photocurrent density (Jsc) than those of conventional TiO2@QDs and ZnO@QDs photoanodes, respectively. Comprehensive optical and electrochemical measurements reveal that the rough surface of m-ZnO can significantly improve the light-harvesting capacity of corresponding photoanodes through surface-enhanced light scattering. Moreover, the Ov in m-ZnO facilitate the interfacial transfer of photogenerated electrons. Our findings indicate that the MOFs are valuable precursors for the preparation of porous films, offering a promising route to develop high-performance QDs-based PEC devices.
Abstract:
Nickle-based catalysts are commonly used for CO2 methanation. However, there is still potential to improve their catalytic performance under mild conditions. In this study, we synthesized a series of Ru-Ni-Al catalysts from Ru-doped NiAl-hydrotalcite using a hydrothermal method. The Ru-Ni-Al catalyst demonstrated much higher activity for CO2 methanation than the Ni-Al catalyst that did not have Ru doping. Both experimental results and theoretical calculations indicate that the enhanced performance of the Ru-Ni-Al catalyst is related to electronic interactions between nickel (Ni) and ruthenium (Ru). The Ru sites transfer electrons to the Ni sites, increasing the local electron density of Ni, which enhances the adsorption and activation of H2. Furthermore, the Ru-Ni metal interface sites improve the adsorption and activation of CO2. In situ Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) analysis indicates that adjusting the electronic structure of Ni sites can accelerate the production of intermediates HCOO*, while Ru-Ni intermetallic interface sites can directly dissociate CO2 into CO*. In addition, CO2 methanation on the Ru-Ni-Al catalyst follows HCOO*- and CO*-mediated pathways. This study underscores the potential for enhancing CO2 methanation performance by modulating the electronic structure of Ni sites.
Abstract:
Severe lithium dendrite growth and elevated thermal runaway risks pose significant hurdles for fast-charging lithium metal batteries (LMBs). This study reports a polydopamine-functionalized hydroxyapatite/aramid (PDA@HA) hybrid nanofibers separator to synchronously improve the fast-charging LMB's stability and safety. (1) The separator's surface, enriched with lithiophilic carbonyl and hydroxyl groups, accelerates Li+ ion desolvation, while electrophilic imine groups impede anion movement. This dual mechanism optimizes the Li+-ion flux distribution on the anode, mitigating dendrite formation. (2) The polar PDA modification layer fosters the development of a Li3N/LiF-rich solid electrolyte interface, further enhancing Li anode stability. Consequently, Li//Li symmetric cells with PDA@HA separators exhibit extended cycle life in Li plating/stripping tests: 5000 h at 1 mA cm-2 and 700 h at 20 mA cm-2, respectively, outperforming PP separators (80 h and 8 h). In LiFePO4 (LFP, ~2.1 mg cm-2)//Li full cell evaluation, the PDA@HA separator enables stable operation for 11,000 cycles at 18.2C with 87% capacity retention, significantly outperforming existing fast-charging LMB counterparts in literature. At a high LFP loading of 15.5 mg cm-2, the cell maintains 137.6 mAh g-1 (2.13 mAh cm-2) over 250 cycles at 3C, achieving 98% capacity retention. Moreover, the PDA@HA separator increases threshold temperature for thermal runaway and reduces the exothermic rate, intensifying the battery's thermal safety. This research underscores the importance of functional separator design in improving Li metal anode reversibility, fast-charging performance, and thermal safety of LMBs.
Abstract:
The synergistic degradation of contaminants in water by photocatalysis and peroxydisulfate (PDS) activation has been proven to be a promising combined advanced oxidation technology. Consequently, the development of highly efficient photocatalysts that are activated by visible light and PDS is of immense importance. Herein, different proportions of cobalt-doped Bi2Fe4O9 (BFO@Co-x) photocatalysts were effectively synthesized for elimination of ciprofloxacin (CIP). The degradation efficiency of CIP achieved by the BFO@Co/Vis/PDS system attained 84.49% (k = 0.0516 min-1) under 40 min light irradiation, outperforming the BFO@Co/Vis and PDS/Vis systems by a factor of 1.45 and 3.6, respectively. Characterization and photoelectric performance assessments revealed that the fabrication of BFO@Co-0.5 was successful, enhancing the photocatalytic degradation efficiency under the synergistic effect of PDS. Moreover, the BFO@Co/Vis/PDS system demonstrated favorable adaptability to various pH, inorganic anions, and humic acid in solution. Additionally, the degradation pathways of CIP and the toxicity of products were evaluated using LC/MS and T.E.S.T software, indicating a reduction in the toxicity of CIP degradation products. This study may provide insights into the application of photocatalyst/Vis/PDS combined systems in the field of water environmental treatment.
Abstract:
The pursuit of sustainable energy has driven a significant interest in hydrogen (H2) as a clean fuel alternative. A critical challenge is the efficient storage of H2, which this study addresses by examining the potential of tricycloquinazoline-based monolayer metal-organic frameworks (MMOFs with the first “M” representing metal species). Using density functional theory, we optimized the structures of MMOFs and calculated H2 adsorption energies above the open metal sites, identifying ScMOF, TiMOF, NiMOF, and MgMOF for further validation of their thermodynamic stability via ab-initio molecular dynamics (AIMD) simulations. Force field parameters were fitted via the Morse potential, providing a solid foundation for subsequent grand canonical Monte Carlo simulations. These simulations revealed that the maximum of saturated excess gravimetric H2 uptake exceeds 14.16 wt% at 77 K, surpassing other reported MOFs, whether they possess open metal sites or not. At 298 K and 100 bar, both the planar and distorted structures derived from our AIMD simulations demonstrated comparable excess gravimetric H2 uptake within the range of 3.05 wt% to 3.94 wt%, once again outperforming other MOFs. Furthermore, lithium (Li) doping significantly enhanced the excess H2 uptake, with Li-TiMOF achieving an impressive 6.83 wt% at 298 K and 100 bar, exceeding the ultimate target set by the U.S. Department of Energy. The exceptional H2 adsorption capacities of these monolayer MOFs highlight their potential in H2 storage, contributing to the design of more efficient hydrogen storage materials and propelling the sustainable hydrogen economy forward.
Abstract:
Concurrent activation of lattice oxygen (OL) and molecular oxygen (O2) is crucial for the efficient catalytic oxidation of biomass-derived molecules over metal oxides. Herein, we report that the introduction of ultralow-loading of Ru single atoms (0.42 wt%) into Mn2O3 matrix (0.4%Ru-Mn2O3) greatly boosts its catalytic activity for the aerobic oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA). The FDCA productivity over the 0.4%Ru-Mn2O3 (5.4 mmolFDCA gcat-1 h-1) is 4.9 times higher than the Mn2O3. Especially, this FDCA productivity is also significantly higher than that of existing Ru and Mn-based catalysts. Experimental and theoretical investigations discovered that the Ru single atom facilitated the formation of oxygen vacancy (Ov) in the catalyst, which synergistically weakened the Mn-O bond and promoted the activation of OL. The co-presence of Ru single atoms and Ov also promote the adsorption and activation of both O2 and HMF. Consequently, the dehydrogenation reaction energy barrier of the rate-determining step was reduced via both the OL and chemisorbed O2 dehydrogenation pathways, thus boosting the catalytic oxidation reactions.
Abstract:
In this study, a novel Pt-loaded CuPc/g-C3N4 (PtCuCN) composite was synthesized for the selective photocatalytic reduction of CO2 to CH4 under visible light. The PtCuCN catalyst achieved a CH4 yield of 39.8 μmol g-1 h-1, significantly outperforming bulk g-C3N4 and CuPc alone by factors of 2.5 and 3.1, respectively, with a high selectivity of 90%. In comparison with other commonly studied photocatalysts, such as g-C3N4-based catalysts, the PtCuCN composite exhibited superior CH4 yield and product selectivity, demonstrating its potential as a more efficient photocatalyst for CO2 reduction. X-ray photoelectron spectroscopy (XPS), density functional theory (DFT) calculations, and in-situ infrared (IR) analysis revealed that the Pt0 species effectively lower the activation energy for CH4 formation, while CuPc extends the light absorption range and enhances charge separation. The combined effects of these components in a Z-scheme heterojunction provide new insights into designing highly selective CO2-to-CH4 photocatalysts. This work demonstrates the potential of PtCuCN as a highly efficient and stable catalyst for CO2 reduction to CH4 under visible light.