2024 Vol. 9, No. 3

Research Highlight
Abstract:
Direct air capture (DAC) has attracted increasing interest and investment over the past few years. There are a fast-growing number of companies that entered the field and demonstrated DAC carbon removal setups and potential. However, current DAC methods are still based on solid absorbents or alkali solutions approaches which have low capture efficiency and low energy efficiency. This highlight proposed a promising CO2 capture technology, an electric energy driven closed-loop system for the direct removal of CO2 from ambient air which are based on two individual technologies: Polyam-N-Cu hybrid system promoted CO2 capture with ocean as anthropogenic CO2 sink and a chloride-mediated electrochemical pH swing system to remove CO2 from oceanwater.
Review articles
Abstract:
The existence and risk of emerging organic contaminants (EOCs) have been under consideration and paid much effort to degrade these pollutants. Fenton system is one of the most widely used technologies to solve this problem. The original Fenton system relies on the hydroxyl radicals produced by Fe(II)/H2O2 to oxidize the organic contaminants. However, the application of the Fenton system is limited by its low iron cycling efficiency and the high risks of hydrogen peroxide transportation and storage. The introduction of external energy (including light and electricity etc.) can effectively promote the Fe(III)/Fe(II) cycle and the reduction of oxygen to produce hydrogen peroxide in situ. This review introduces three in-situ Fenton systems, which are electro-Fenton, Photo-Fenton, and chemical reaction. The mechanism, influencing factors, and catalysts of these three in-situ Fenton systems in degrading EOCs are discussed systematically. This review strengthens the understanding of Fenton and in-situ Fenton systems in degradation, offering further insight into the real application of the in-situ Fenton system in the removal of EOCs.
Abstract:
The transformation of aldose to ketose or common sugars into rare saccharides, including rare ketoses and aldoses, is of great value and interest to the food industry and for saccharidic biomass utilization, medicine, and the synthesis of drugs. Nowadays, high-fructose corn syrup (HFCS) is industrially produced in more than 10 million tons annually using immobilized glucose isomerase. Some low-calorie saccharides such as tagatose and psicose, which are becoming popular sweeteners, have also been produced on a pilot scale in order to replace sucrose and HFCS. However, current catalysts and catalytic processes are still difficult to utilize in biomass conversion and also have strong substrate dependence in producing high-value, rare sugars. Considering the specific reaction properties of saccharides and catalysts, since the pioneering discovery by Fischer, various catalysts and catalytic systems have been discovered or developed in attempts to extend the reaction pathways, improve the reaction efficiency, and to potentially produce commercial products. In this review, we trace the history of sugar isomerization/epimerization reactions and summarize the important breakthroughs for each reaction as well as the difficulties that remain unresolved to date.
Abstract:
As a key material for lithium metal batteries (LMBs), lithium metal is one of the most promising anode materials to break the bottleneck of battery energy density and a commonly used active material for reference electrodes. Although lithium anodes are regarded as the holy grail of lithium batteries, decades of exploration have not led to the successful commercialization of LMBs, due mainly to the challenges related to the inherent properties of lithium metal. To pave the way for further investigation, herein, a comprehensive review focusing on the fundamental science of lithium are provided. Firstly, the natures of lithium atoms and their isotopes, lithium clusters and lithium crystals are revisited, especially their structural and energetic properties. Subsequently, the electrochemical properties of lithium metal are reviewed. Numerous important concepts and scientific questions, including the electronic structure of lithium, influence of high pressure and low temperature on the properties of lithium, factors influencing lithium deposition, generation of lithium dendrites, and electrode potential of lithium in different electrolytes, are explained and analyzed in detail. Approaches to improve the performance of lithium anodes and thoughtfulness about the electrode potential in lithium battery research are proposed.
Research papers
Abstract:
The ionic transport in sub-nanochannels plays a key role in energy storage, yet suffers from a high energy barrier. Wetting sub-nanochannels is crucial to accelerate ionic transport, but the introduction of water is challenging because of the hydrophobic extreme confinement. We propose wetting the channels by the exothermic hydration process of pre-intercalated ions, the effect of which varies distinctly with different ionic hydration structures and energies. Compared to the failed pre-intercalation of SO42-, HSO4- with weak hydration energy results in a marginal effect on the HOMO (Highest Occupied Molecular Orbital) level of water to avoid water splitting during the electrochemical intercalation. Meanwhile, the ability of water introduction is reserved by the initial incomplete dissociation state of HSO4-, so the consequent exothermic reionization and hydration processes of the intercalated HSO4- promote the water introduction into sub-nanochannels, finally forming the stable confined water through hydrogen bonding with functional groups. The wetted channels exhibit a significantly enhanced ionic diffusion coefficient by ~9.4 times.
Abstract:
A novel photo-catalytic system composed of N-doped biochars (NBCs), MnFe2O4 and sulfite activation under ultraviolet (NBCs/MnFe2O4/sulfite/UV) was constructed to realize the efficient eliminate of tetracycline (TC). As the carrier of MnFe2O4, NBCs were synthesized from alfalfa, which has large specific surface area, graphite like structure and hierarchical porous structure. The adsorption isotherm indicated that NBCs/MnFe2O4-2:1 had the best adsorption performance for TC (347.56 mg g-1). Through synergistic adsorption and photocatalysis, the removal rate of TC reached 84%, which was significantly higher than that of MnFe2O4. Electrochemical impedance spectroscopy (EIS) and Photoluminescence (PL) characterization results showed that the introduction of NBCs improved the separation efficiency of photogenerated electron and hole pairs and enhanced the photocatalytic performance. Moreover, the adsorption, degradation mechanism and degradation path of TC by the catalyst were systematically analyzed by coupling HPLC–MS measurement with the theoretical calculation. Considering the advantages of excellent degradation performance, low cost, easy separation and environmental friendliness of NBCs/MnFe2O4, this work was expected to provide a new path for the practical application of biochar.
Abstract:
A few-layered hexagonal boron nitride nanosheets stabilized platinum nanoparticles (Pt/h-BNNS) is engineered for oxidation-promoted adsorptive desulfurization (OPADS) of fuel oil. It was found that the few-layered structure and the defective sites of h-BNNS not only are beneficial to the stabilization of Pt NPs but also favor the adsorption of aromatic sulfides. By employing Pt/h-BNNS with a Pt loading amount of 1.19 wt% as the active adsorbent and air as an oxidant, a 98.0% sulfur removal over dibenzothiophene (DBT) is achieved along with a total conversion of the DBT to the corresponding sulfones (DBTO2). Detailed experiments show that the excellent desulfurization activity originates from the few-layered structure of h-BNNS and the high catalytic activity of Pt NPs. In addition, the OPADS system with Pt/h-BNNS as the active adsorbent shows remarkable stability in desulfurization performance with the existence of different interferents such as olefin, and aromatic hydrocarbons. Besides, the Pt/h-BNNS can be recycled 12 times without a significant decrease in desulfurization performance. Also, a process flow diagram is proposed for deep desulfurization of fuel oil and recovery of high value-added products, which would promote the industrial application of such OPADS strategy.
Abstract:
Temperature-swing adsorption (TSA) is an effective technique for CO2 capture, but the temperature swing procedure is energy-intensive. Herein, we report a low-energy-consumption system by combining passive radiative cooling and solar heating for the uptake of CO2 on commercial activated carbons (CACs). During adsorption, the adsorbents are coated with a layer of hierarchically porous poly(vinylidene fluoride-co-hexafluoropropene) [P(VdF-HFP)HP], which cools the adsorbents to a low temperature under sunlight through radiative cooling. For desorption, CACs with broad absorption of the solar spectrum are exposed to light irradiation for heating. The heating and cooling processes are completely driven by solar energy. Adsorption tests under mimicked sunlight using the CACs show that the performance of this system is comparable to that of the traditional ones. Furthermore, under real sunlight irradiation, the adsorption capacity of the CACs can be well maintained after multiple cycles. The present work may inspire the development of new temperature swing procedures with little energy consumption.
Abstract:
The pursuit of high-performance is worth considerable effort in catalysis for energy efficiency and environmental sustainability. To develop redox catalysts with superior performance for soot combustion, a series of MnxCoy oxides were synthesized using MgO template substitution. This method greatly improves the preparation and catalytic efficiency and is more in line with the current theme of green catalysts and sustainable development. The resulting Mn1Co2.3 has a strong activation capability of gaseous oxygen due to a high concentration of Co3+ and Mn3+. The Mn doping enhanced the intrinsic activity by prompting oxygen vacancy formation and gaseous oxygen adsorption. The nanosheet morphology with abundant mesoporous significantly increased the solid–solid contact efficiency and improved the adsorption capability of gaseous reactants. The novel design of Mn1Co2.3 oxide enhanced its catalytic performance through a synergistic effect of Mn doping and the porous nanosheet morphology, showing significant potential for the preparation of high-performance soot combustion catalysts.
Abstract:
Dehydrogenation is considered as one of the most important industrial applications for renewable energy. Cubic ceria-based catalysts are known to display promising dehydrogenation performances in this area. Large particle size (>20 nm) and less surface defects, however, hinder further application of ceria materials. Herein, an alternative strategy involving lactic acid (LA) assisted hydrothermal method was developed to synthesize active, selective and durable cubic ceria of <6 nm for dehydrogenation reactions. Detailed studies of growth mechanism revealed that, the carboxyl and hydroxyl groups in LA molecule synergistically manipulate the morphological evolution of ceria precursors. Carboxyl groups determine the cubic shape and particle size, while hydroxyl groups promote compositional transformation of ceria precursors into CeO2 phases. Moreover, enhanced oxygen vacancies (Vö) on the surface of CeO2 were obtained owing to continuous removal of O species under reductive atmosphere. Cubic CeO2 catalysts synthesized by the LA-assisted method, immobilized with bimetallic PtCo clusters, exhibit a record high activity (TOF: 29,241 h-1) and Vö-dependent synergism for dehydrogenation of bio-derived polyols at 200 °C. We also found that quenching Vö defects at air atmosphere causes activity loss of PtCo/CeO2 catalysts. To regenerate Vö defects, a simple strategy was developed by irradiating deactivated catalysts using hernia lamp. The outcome of this work will provide new insights into manufacturing durable catalyst materials for aqueous phase dehydrogenation applications.
Abstract:
Electrocatalytic nitrogen reduction reaction (NRR) is considered as a promising candidate to achieve ammonia synthesis because of clean electric energy, moderate reaction condition, safe operating process and harmless by-products. However, the chemical inertness of nitrogen and poor activated capacity on catalyst surface usually produce low ammonia yield and faradic efficiency. Herein, the microfluidic technology is proposed to efficiently fabricate enriched iridium nanodots/carbon architecture. Owing to in-situ co-precipitation reaction and microfluidic manipulation, the iridium nanodots/carbon nanomaterials possess small average size, uniform dispersion, high conductivity and abundant active sites, producing good proton activation and rapid electrons transmission and moderate adsorption/desorption capacity. As a result, the as-prepared iridium nanodots/carbon nanomaterials realize large ammonia yield of 28.73 μg h-1 cm-2 and faradic efficiency of 9.14% in KOH solution. Moreover, the high ammonia yield of 11.21 μg h-1 cm-2 and faradic efficiency of 24.30% are also achieved in H2SO4 solution. The microfluidic method provides a reference for large-scale fabrication of nano-sized catalyst materials, which may accelerate the progress of electrocatalytic NRR in industrialization field.
Abstract:
Developing single-crystalline Ni-rich cathodes is an effective strategy to improve the safety and cycle life of Li-ion batteries (LIBs). However, the easy-to-loss of Li and O in high-temperature lithiation results in unsatisfactory ordered layered structure and stoichiometry. Herein, we demonstrate the synthesis of highly-ordered and fully-stoichiometric single-crystalline LiNi0.83Co0.12Mn0.05O2 (SC-NCM83) cathodes by the regulation of pre-lithiation kinetics. The well-balanced pre-lithiation kinetics have been proved to greatly improve the proportion of layered phase in the intermediate by inhibiting the formation of metastable spinel phase, which promoted the rapid transformation of the intermediate into highly-ordered layered SC-NCM83 in the subsequent lithiation process. After coating a layer of Li2O–B2O3, the resultant cathodes deliver superior cycling stability with 90.9% capacity retention at 1C after 300 cycles in pouch-type full batteries. The enhancement mechanism has also been clarified. These findings exhibit fundamental insights into the pre-lithiation kinetics process for guiding the synthesis of high-quality single-crystalline Ni-rich cathodes.
Abstract:
Lithium-sulfur batteries (LSBs) with high energy densities have been demonstrated the potential for energy-intensive demand applications. However, their commercial applicability is hampered by hysteretic electrode reaction kinetics and the shuttle effect of lithium polysulfides (LiPSs). In this work, an interlayer consisting of high-entropy metal oxide (Cu0.7Fe0.6Mn0.4Ni0.6Sn0.5)O4 grown on carbon nanofibers (HEO/CNFs) is designed for LSBs. The CNFs with highly porous networks provide transport pathways for Li+ and e-, as well as a physical sieve effect to limit LiPSs crossover. In particular, the grapevine-like HEO nanoparticles generate metal-sulfur bonds with LiPSs, efficiently anchoring active materials. The unique structure and function of the interlayer enable the LSBs with superior electrochemical performance, i.e., the high specific capacity of 1381 mAh g-1 at 0.1 C and 561 mAh g-1 at 6 C. This work presents a facile strategy for exploiting high-performance LSBs.
Abstract:
Lithium-ion capacitors (LICs) combining the advantages of lithium-ion batteries and supercapacitors are considered a promising next-generation energy storage device. However, the sluggish kinetics of battery-type anode cannot match the capacitor-type cathode, restricting the development of LICs. Herein, hierarchical carbon framework (HCF) anode material composed of 0D carbon nanocage bridged with 2D graphene network are developed via a template-confined synthesis process. The HCF with nanocage structure reduces the Li+ transport path and benefits the rapid Li+ migration, while 2D graphene network can promote the electron interconnecting of carbon nanocages. In addition, the doped N atoms in HCF facilitate to the adsorption of ions and enhance the pseudo contribution, thus accelerate the kinetics of the anode. The HCF anode delivers high specific capacity, remarkable rate capability. The LIC pouch-cell based on HCF anode and active HCF (a-HCF) cathode can provide a high energy density of 162 Wh kg-1 and a superior power density of 15.8 kW kg-1, as well as a long cycling life exceeding 15,000 cycles. This study demonstrates that the well-defined design of hierarchical carbon framework by incorporating 0D carbon nanocages and 2D graphene network is an effective strategy to promote LIC anode kinetics and hence boost the LIC electrochemical performance.
Abstract:
Dwindling energy sources and a worsening environment are huge global problems, and biomass wastes are an under-exploited source of material for both energy and material generation. Herein, self-template decoction dregs of Ganoderma lucidum-derived porous carbon nanotubes (ST-DDLGCs) were synthesized via a facile and scalable strategy in response to these challenges. ST-DDLGCs exhibited a large surface area (1731.51 m2 g-1) and high pore volume (0.76 cm3 g-1), due to the interlacing tubular structures of precursors and extra-hierarchical porous structures on tube walls. In the ST-DDLGC/PMS system, the degradation efficiency of capecitabine (CAP) reached ~97.3% within 120 min. Moreover, ST-DDLGCs displayed high catalytic activity over a wide pH range of 3–9, and strong anti-interference to these typical and ubiquitous anions in wastewater and natural water bodies (i.e., H2PO4-, NO3-, Cl- and HCO3-), in which a 1O2-dominated oxidation was identified and non-radical mechanisms were deduced. Additionally, ST-DDLGC-based coin-type symmetrical supercapacitors exhibited outstanding electrochemical performance, with specific capacitances of up to 328.1 F g-1 at 0.5 A g-1, and cycling stability of up to 98.6% after 10,000 cycles at a current density of 2 A g-1. The superior properties of ST-DDLGCs could be attributed to the unique porous tubular structure, which facilitated mass transfer and presented numerous active sites. The results highlight ST-DDLGCs as a potential candidate for constructing inexpensive and advanced environmentally functional materials and energy storage devices.
Corrigendum
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