Current Issue

2024 Vol. 9, No. 11

Perspective
Abstract:
Aqueous organic redox flow batteries (AORFBs) have pioneered new routes for large-scale energy storage. The tunable nature of redox-active organic molecules provides a robust foundation for creating innovative AORFBs with exceptional performance. Molecular engineering endows various organic molecules with considerable advantages in solubility, stability, and redox potential. Advanced characterizations have enabled a comprehensive understanding of the redox reaction and degradation mechanisms of these organic molecules. Computational chemistry and machine learning have guided the development of new organic molecules. The practical application of AORFBs will depend on the complementary efforts of multiple parties. This paper consolidates the current design principles of molecular engineering, degradation mechanisms, characterization techniques, and the utilization of computational chemistry. It also offers perspectives and forecasts the necessary attributes and strategic efforts for the next-generation AORFBs, aiming to provide the research community with a deeper understanding.
Short review
Abstract:
Polyethylene terephthalate (PET) as one of non-degradable wastes has become a huge threat to the environment and human health. Chemical Recycle of PET is a sustainable way to release 1,4-benzenedicarboxylic acid (BDC) the monomer of PET as common used organic linker for synthesis of functional Metal-organic-frameworks (PET-derived MOFs) such as UiO-66, MIL-101, etc. This sustainable and cost-effective “Waste-to-MOFs” model is of great significant to be intensively investigated in the past years. Attributes of substantial porosity, specific surface area, exposed metal centers, uniform structure, and flexible morphology render PET-derived MOFs are well-suited for applications in adsorption, energy storage, catalysis, among others. Herein, in the present work, we have summarized recent advances in synthesis of PET-derived MOFs using ex-situ and in-situ methods for typical applications of adsorption, catalysis and energy storage. Despite those improvements in synthesis methods and potential applications, challenges still remain in development of green and economical routes to fully utilize waste PET for massive manufacture of valuable MOF materials and chemicals. This review provides insights into the conversion of non-degradable PET waste to value-added MOF materials, and further suggests promising perspectives to develop the sustainable “Waste-to-MOFs” model in addressing environmental pollution and energy crises.
Review articles
Abstract:
Emerging contaminants (ECs) are widely present in aquatic environments, posing potential risks to both ecosystems and human health. The ultrasound-assisted persulfate oxidation process has attracted considerable attention in the degradation of ECs due to its ability to generate both sulfate radicals and cavitation effects, enhancing degradation effects. In this paper, the principle of ultrasonic synergistic Fenton-like oxidation system for degrading organic pollutants was reviewed, divided into homogeneous system, non-homogeneous system, and single-atom system to explore the synergistic effect of ultrasound-enhanced persulfate technology in three aspects, and the effects of environmental factors such as ultrasonic frequency and power, system pH, temperature, and initial oxidant concentration on the system's decontamination performance were discussed. Finally, future research on ultrasonically activated persulfate technology is summarized and prospected.
Abstract:
Mineral carbonation is a promising CO2 sequestration strategy that can utilize industrial wastes to convert CO2 into high-value CaCO3. This review summarizes the advancements in CO2 mineralization using typical industrial wastes to prepare ultrafine CaCO3. This work surveys the mechanisms of CO2 mineralization using these wastes and its capacities to synthesize CaCO3, evaluates the effects of carbonation pathways and operating parameters on the preparation of CaCO3, analyzes the current industrial application status and economics of this technology. Due to the large amount of impurities in solid wastes, the purity of CaCO3 prepared by indirect methods is greater than that prepared by direct methods. Crystalline CaCO3 includes three polymorphs. The polymorph of CaCO3 synthesized by carbonation process is determined the combined effects of various factors. These parameters essentially impact the nucleation and growth of CaCO3 by altering the CO2 supersaturation in the reaction system and the surface energy of CaCO3 grains. Increasing the initial pH of the solution and the CO2 flow rate favors the formation of vaterite, but calcite is formed under excessively high pH. Vaterite formation is favored at lower temperatures and residence time. With increased temperature and prolonged residence time, it passes through aragonite metastable phase and eventually transforms into calcite. Moreover, polymorph modifiers can decrease the surface energy of CaCO3 grains, facilitating the synthesis of vaterite. However, the large-scale application of this technology still faces many problems, including high costs, high energy consumption, low calcium leaching rate, low carbonation efficiency, and low product yield. Therefore, it is necessary to investigate ways to accelerate carbonation, optimize operating parameters, develop cost-effective agents, and understand the kinetics of CaCO3 nucleation and crystallization to obtain products with specific crystal forms. Furthermore, more studies on life cycle assessment (LCA) should be conducted to fully confirm the feasibility of the developed technologies.
Research papers
Abstract:
Interfacial solar-driven evaporation technology shows great potential in the field of industrial seawater desalination, and the development of efficient and low-cost evaporation materials is key to achieving large-scale applications. Hydrogels are considered to be promising candidates; however, conventional hydrogel-based interfacial solar evaporators have difficulty in simultaneously meeting multiple requirements, including a high evaporation rate, salt resistance, and good mechanical properties. In this study, a Janus sponge-like hydrogel solar evaporator (CPAS) with excellent comprehensive performance was successfully constructed. The introduction of biomass agar (AG) into the polyvinyl alcohol (PVA) hydrogel backbone reduced the enthalpy of water evaporation, optimized the pore structure, and improved the mechanical properties. Meanwhile, by introducing hydrophobic fumed nano-silica aerogel (SA) and a synergistic foaming-crosslinking process, the hydrogel spontaneously formed a Janus structure with a hydrophobic surface and hydrophilic bottom properties. Based on the reduction of the evaporation enthalpy and the modulation of the pore structure, the CPAS evaporation rate reached 3.56 kg m-2 h-1 under one sun illumination. Most importantly, owing to the hydrophobic top surface and 3D-interconnected porous channels, the evaporator could work stably in high concentrations of salt-water (25 wt% NaCl), showing strong salt resistance. Efficient water evaporation, excellent salt resistance, scalable preparation processes, and low-cost raw materials make CPAS extremely promising for practical applications.
Abstract:
Water stability is one of the most important factors restricting the practical application of metal organic frameworks (MOFs). In this work, we fabricate a highly defective HKUST-1 framework with a mixed valence of CuI/CuII by mechanical ball milling method. This defective HKUST-1 is embellished by functionalized ionic liquids as hydrophobic armor, making the hybrid HIL1@HKUST-1 exhibits outstanding water stability, remarkable SO2 adsorption (up to 5.71 mmol g-1), and record-breaking selectivity (1070 for SO2/CO2 and 31,515 for SO2/N2) at 25 ℃ and 0.1 bar, even in wet conditions.
Abstract:
KFeSO4F (KFSF) is considered a potential cathode due to the large capacity and low cost. However, the inferior electronic conductivity leads to poor electrochemical performance. Defect engineering can facilitate the electron/ion transfer by tuning electronic structure, thus providing favorable electrochemical performance. Herein, through the regulation of surface defect engineering in reduced graphene oxide (rGO), the Fe-C bonds were formed between KFSF and rGO. The Fe-C bonds formed work in regulating the Fe-3d orbital as well as promoting the migration ability of K ions and increasing the electronic conductivity of KFSF. Thus, the KFSF@rGO delivers a high capacity of 119.6 mAh g-1. When matched with a graphite@pitch-derived S-doped carbon anode, the full cell delivers an energy density of 250.5 Wh kg-1 and a capacity retention of 81.5% after 400 cycles. This work offers a simple and valid method to develop high-performance cathodes by tuning defect sites.
Abstract:
High-performance proton exchange membranes are of great importance for fuel cells. Here, we have synthesized polycarboxylate plasticizer modified MIL-101-Cr-NH2 (PCP-MCN), a kind of hybrid metal-organic framework, which exhibits a superior proton conductivity. PCP-MCN nanoparticles are used as additives to fabricate PCP-MCN/Nafion composite membranes. Microstructures and characteristics of PCP-MCN and these membranes have been extensively investigated. Significant enhancement in proton conduction for PCP-MCN around 55 ℃ is interestingly found due to the thermal motion of the PCP molecular chains. Robust mechanical properties and higher thermal decomposition temperature of the composite membranes are directly ascribed to strong intermolecular interactions between PCP-MCN and Nafion side chains, i.e., the formation of substantial acid-base pairs (-SO3-···+H-NH-), which further improves compatibility between additive and Nafion matrix. At the same humidity and temperature condition, the water uptake of composite membranes significantly increases due to the incorporation of porous additives with abundant functional groups and thus less crystallinity degree in comparison to pristine Nafion. Proton conductivity (σ) over wide ranges of humidities (30 - 100% RH at 25 ℃) and temperatures (30 - 98 ℃ at 100% RH) for prepared membranes is measured. The σ in PCP-MCN/Nafion composite membranes is remarkably enhanced, i.e. 0.245 S/cm for PCP-MCN-3wt.%/Nafion is twice that of Nafion membrane at 98 ℃ and 100% RH, because of the establishment of well-interconnected proton transport ionic water channels and perhaps faster protonation-deprotonation processes. The composite membranes possess weak humidity-dependence of proton transport and higher water uptake due to excellent water retention ability of PCP-MCN. In particular, when 3 wt.% PCP-MCN was added to Nafion, the power density of a single-cell fabricated with this composite membrane reaches impressively 0.480, 1.098 W/cm2 under 40% RH, 100% RH at 60 ℃, respectively, guaranteeing it to be a promising proton exchange membrane.
Abstract:
Polymer flooding is an effective method widely applied for enhancing oil recovery (EOR) by reducing the mobility ratio between the injected water and crude oil. However, traditional polymers encounter challenges in high salinity reservoirs due to their salt sensitivity. To overcome this challenge, we synthesized a zwitterion polymer (PAMNS) with salt-induced tackifying property through copolymerization of acrylamide and a zwitterion monomer, methylacrylamide propyl-N, N-dimethylbutylsulfonate (NS). NS monomer is obtained from the reaction between 1,4-butanesultone and dimethylamino propyl methylacrylamide. In this study, the rheological properties, salt responsiveness, and EOR efficiency of PAMNS were evaluated. Results demonstrate that PAMNS exhibits desirable salt-induced tackifying characteristics, with viscosity increasing up to 2.4 times as the NaCl concentration reaches a salinity of 30×104 mg L-1. Furthermore, high valence ions possess a much stronger effect on enhancing viscosity, manifested as Mg2+ > Ca2+ > Na+. Molecular dynamics simulations (MD) and fluid dynamics experiment results demonstrate that PAMNS molecules exhibit a more stretched state and enhanced intermolecular associations in high-salinity environments. It is because of the salt-induced tackifying, PAMNS demonstrates superior performance in polymer flooding experiments under salinity ranges from 5×104 mg L-1 to 20×104 mg L-1, leading to 10.38-19.83% higher EOR than traditional polymers.
Abstract:
For decades micoorganisms have been engineered for the utilization of lignocellulose-based second-generation (2G) feedstocks, but with the concerns of increased levels of atmospheric CO2 causing global warming there is an emergent need to transition from the utilization of 2G feedstocks to third-generation (3G) feedstocks such as CO2 and its derivatives. Here, we established a yeast platform that is capable of simultaneously converting 2G and 3G feedstocks into bulk and value-added chemicals. We demonstrated that by adopting 3G substrates such as CO2 and formate, the conversion of 2G feedstocks could be substantially improved. Specifically, formate could provide reducing power and energy for xylose conversion into valuable chemicals. Simultaneously, it can form a concentrated CO2 pool inside the cell, providing thermodynamically and kinetically favoured amounts of precursors for CO2 fixation pathways, e.g., the Calvin-Benson-Bassham (CBB) cycle. Furthermore, we demonstrated that formate could directly be utilized as a carbon source by yeast to synthesize endogenous amino acids. The engineered strain achieved a one-carbon (C1) assimilation efficiency of 9.2%, which was the highest efficiency observed in the co-utilization of 2G and 3G feedstocks. We applied this strategy for productions of both bulk and value-added chemicals, including ethanol, free fatty acids (FFAs), and longifolene, resulting in yield enhancements of 18.4%, 49.0%, and ~100%, respectively. The strategy demonstrated here for co-utilization of 2G and 3G feedstocks sheds lights on both basic and applied research for the up-coming establishment of 3G biorefineries.
Abstract:
A two-stage catalytic membrane reactor (CMR) that couples CO2 splitting with methane oxidation reactions was constructed based on an oxygen-permeable perovskite asymmetric membrane. The asymmetric membrane comprises a dense SrFe0.9Ta0.1O3-δ (SFT) separation layer and a porous Sr0.9(Fe0.9Ta0.1)0.9Cu0.1O3-δ (SFTC) catalytic layer. In the first stage reactor, a CO2 splitting reaction (CDS: 2CO2 → 2CO + O2) occurs at the SFTC catalytic layer. Subsequently, the O2 product is selectively extracted through the SFT separation layer to the permeated side for the methane combustion reaction (MCR), which provides an extremely low oxygen partial pressure to enhance the oxygen extraction. In the second stage, a Sr0.9(Fe0.9Ta0.1)0.9Ni0.1O3-δ (SFTN) catalyst is employed to reform the products derived from MCR. The two-stage CMR design results in a remarkable 35.4% CO2 conversion for CDS at 900 ℃. The two-stage CMR was extended to a hollow fiber configuration combining with solar irradiation. The solar-assisted two-stage CMR can operate stably for over 50 h with a high hydrogen yield of 18.1 mL min-1 cm-2. These results provide a novel strategy for reducing CO2 emissions, suggesting potential avenues for the design of the high-performance CMRs and catalysts based on perovskite oxides in the future.