As hot topics in the chemical conversion of CO2, the photo‐/electrocatalytic reduction of CO2 and use of CO2 as a supporter for energy storage have shown great potential for the utilization of CO2. ...However, many obstacles still exist on the road to realizing highly efficient chemical CO2 conversion, such as inefficient uptake/activation of CO2 and mass transport in catalysts. Covalent organic frameworks (COFs), as a kind of porous material, have been widely explored as catalysts for the chemical conversion of CO2 owing to their unique features. In particular, COF‐based functional materials containing diverse active sites (such as single metal sites, metal nanoparticles, and metal oxides) offer great potential for realizing CO2 conversion and energy storage. This Minireview discusses recent breakthroughs in the basic knowledge, mechanisms, and pathways of chemical CO2 conversion strategies that use COF‐based functional catalysts. In addition, the challenges and prospects of COF‐based functional catalysts for the efficient utilization of CO2 are also introduced.
This Minireview discusses recent developments in the basic knowledge, mechanisms, and CO2 utilization strategies regarding the use of functional materials based on covalent‐organic frameworks (COFs) with diverse active sites as catalysts. Insight is provided into the challenges and prospects of COF‐based catalysts for the design of the next‐generation photo‐/electrocatalysts for the utilization of CO2.
The identity development process has individual and societal components and is inherently intertwined with one’s broader sociocultural milieu. The correlation between the personal and social aspects ...of an individual’s identity considerably influences their behavior within their environment. This study examines cultural identity changes among English as a Foreign Language (EFL) students by conducting a questionnaire survey based on the anxiety/uncertainty management theory by
Gudykunst (1995
,
1998)
. The questionnaire was distributed twice: Study 1 used data from 483 students and Study 2 used data from 359 students. After each study, 20 students’ descriptions of Chinese and Western cultures were analyzed in NVivo. Guided by the ecological research paradigm, this study examines the impact of individual differences on cultural identity at the macro-, meso-, exo-, and micro- levels. The findings suggest that social context can influence an individual’s cultural identity, and cultural identity development accompanies being “oneself.”
Aqueous Zn‐metal batteries are the most promising system for large‐scale energy storage due to their high capacity, high safety, and low cost. The Zn‐metal anode, however, suffers from continuous ...parasitic reactions, random dendrite growth, and sluggish kinetics in aqueous electrolytes. Herein, a high donor number solvent, tetramethylurea (TMU), is introduced as electrolyte additive to enable highly reversible Zn‐metal anode, where the TMU can 1) preferentially adsorb on the Zn surface to inhibit Zn corrosion and suppress parasitic reaction, 2) solvate with Zn2+ and exclude the H2O from Zn2+ solvation sheath to weaken water activity significantly, and 3) contribute to form an inorganic‐organic bilayer solid electrolyte interphase to enable homogeneous and rapid Zn2+ transport kinetic for dendrite‐free Zn deposition. Benefiting from these three merits, the resulting aqueous electrolyte demonstrates a highly reversible Zn plating/stripping cycling in a Zn||Ti asymmetric cell for over 1200 cycles and in a Zn||Zn symmetric cell for over 4000 h. As a proof‐of‐concept, the aqueous Zn‐metal full cells assembled with various state‐of‐the‐art cathodes also deliver excellent cycling performance even with a 10 µm thin Zn anode, favoring the practical application.
A high donor solvent, tetramethylurea, is introduced as an electrolyte additive to enable highly reversible Zn‐metal anode with superior cyclability under harsh conditions. Rationally, the tetramethylurea can adsorb on the Zn surface to suppress parasitic reaction, solvate with Zn2+ to weaken water activity, and contribute to form an inorganic‐organic bilayer solid electrolyte interphase to enable homogeneous Zn deposition and rapid Zn2+ transport kinetic.
Lithium metal batteries hold great promise for promoting energy density and operating at low temperatures, yet they still suffer from insufficient Li compatibility and slow kinetic, especially at ...ultra‐low temperatures. Herein, we rationally design and synthesize a new amphiphilic solvent, 1,1,2,2‐tetrafluoro‐3‐methoxypropane, for use in battery electrolytes. The lithiophilic segment is readily to solvate Li+ to induce self‐assembly of the electrolyte solution to form a peculiar core‐shell‐solvation structure. Such unique solvation structure not only largely improves the ionic conductivity to allow fast Li+ transport and lower the desolvation energy to enable facile desolvation, but also leads to the formation of a highly robust and conductive inorganic SEI. The resulting electrolyte demonstrates high Li efficiency and superior cycling stability from room temperature to −40 °C at high current densities. Meanwhile, anode‐free high‐voltage cell retains 87 % capacity after 100 cycles.
A new amphiphilic solvent is rationally designed to induce self‐assembly of the electrolyte solution to form a peculiar core‐shell‐solvation structure. Such unique solvation structure bestows improved ionic conductivity, low desolvation energy, and highly robust and conductive SEI, which overcomes the long‐standing Li compatibility and deposition kinetic challenges, enabling the stable operation of Li‐metal battery under ultra‐low temperature.
The precise tuning and multi‐dimensional processing of covalent organic frameworks (COFs)‐based materials into multicomponent superstructures with appropriate diversity are essential to maximize ...their advantages in catalytic reactions. However, up to now, it remains an ongoing challenge for the precise design of COFs‐based multicomponent nanocomposites with diverse architectures. Herein, a metal organic framework (MOF)‐sacrificed in situ acid‐etching (MSISAE) strategy that enables continuous synthesis of core‐shell, yolk‐shell, and hollow‐sphere COFs‐based nanocomposites through tuning of core decomposition (NH2‐MIL‐125 into TiO2) rate is developed. More importantly, due to the multiple active sites, fast transfer of carriers, increased light utilization ability, et al, one of the obtained samples, NH2‐MIL‐125/TiO2@COF‐366‐Ni‐OH‐HAc (yolk‐shell) with special three components, exhibits high photocatalytic CO2‐to‐CO conversion efficiency in the gas‐solid mode. The MSISAE strategy developed in this work achieves the precise morphology design and control of multicomponent hybrid composites based on COFs, which may pave a new way in devealoping porous crystalline materials with powerful superstructures for multifunctional catalytic reactions.
A metal–organic‐framework‐sacrificed in situ acid‐etching strategy to bring about the controllable synthesis of a series of covalent organic framework based multicomponent nanocomposites from core–shell, yolk–shell, and hollow‐sphere structures is presented. Combining the unique yolk–shell structure with the synergistic effects of the three components, the MTCN‐H (ys) demon strates remarkable catalytic performance in photocatalytic reduction of CO2 with H2O.
Si microparticle (SiMP) anodes feature much lower production cost and higher tap density compared to their nanosized counterparts, which hold great promise for high‐energy‐density lithium‐ion ...batteries, yet they suffer from unavoidable particle pulverization during repeated cycling, thus making their practical application extremely challenging. Herein, a non‐flammable localized high‐concentration electrolyte (LHCE) is rationally formulated using a fluorinated solvent, 2,2,2‐trifluoroethyl methyl carbonate (FEMC), to induce fluorinated solvent‐coupled anion‐derived interfacial chemistry. Unlike other LHCEs, the FEMC‐based LHCE is demonstrated to build a highly robust and stable F‐rich inorganic–organic bilayer solid–electrolyte interphase on SiMP anode, which endows stable cycling of SiMP anode (≈3.4 mAh cm−2) with an ultrahigh Coulombic efficiency of ≈99.7%. Coupled with its high anodic stability, the FEMC‐based LHCE endows unprecedented cycling stability for high‐energy‐density batteries containing high‐capacity SiMP anodes with Ni‐rich LiNi8Mn1Co1O2 or 5 V‐class LiNi0.5Mn1.5O4 cathodes. Remarkably, a 1.0 Ah‐level SiMP||LiNi8Mn1Co1O2 pouch‐cell stably operates for more than 200 cycles, representing the pioneering report in pouch cells containing SiMP anodes.
A fluorinated solvent is incorporated into localized high‐concentration electrolyte to induce fluorinated solvent‐coupled anion‐derived interfacial chemistry, which yields a highly robust and stable F‐rich inorganic–organic bilayer solid–electrolyte interphase to enable stable cycling of Si microparticle anode. This electrolyte overcomes the longstanding challenges of Si microparticle pulverization and high‐voltage incompatibility, endowing the stable operation of high‐energy‐density Li‐ion batteries.
An increasing number of industries remove toluene from flue gas by the existing NH3-selective catalytic reduction (NH3-SCR) units. A thorough probe into the impact of NOx and NH3 addition on toluene ...oxidation is imperative but still lacks a unified understanding. In this work, NH3-SCR reactants are found to inhibit the toluene oxidation process over the MnOx-CeO2 catalyst below 200 °C. The competitive adsorption between NH3-SCR reactants and toluene, the NO2 adsorption state, and carbon deposition are emphasized to play important roles in this deactivation. Within the NO2 adsorption states, only the adsorbed NO2 can enhance the toluene oxidation. The formed nitrate species (NO3-) on the surface is inactive. NO2 adsorption is the weakest among the reactants with the smallest adsorption energy of −0.42 eV, restricting its promotion on toluene oxidation. NO and N2O are both demonstrated to be inefficient to oxidize toluene. Meanwhile, MnOx-CeO2 catalyst suffers from serious acetonitrile and benzonitrile poisoning. The amount of nitrile species accounts for ~95% of total carbon deposition, while no simple substance carbon (C) can be generated from CO disproportionation. Special care should be considered towards the formation of environmentally hazardous benzamide in the off-gas from the simultaneous NOx and toluene removal process.
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•NH3-SCR gas inhibits the toluene oxidation process over MnOx-CeO2 catalyst.•Toluene competitively adsorbs with NH3-SCR reactants.•The formed nitrate species is inactive for toluene oxidation.•Nitrile species block the active sites on the catalyst surface.•Environmentally hazardous benzamide is generated in the off-gas.
A lithium-sulfur (Li-S) battery is regarded as the most promising candidate for next generation energy storage systems, because of its high theoretical specific capacity (1675 mA h g
) and specific ...energy (2500 W h kg
), as well as the abundance, low cost and environmental benignity of sulfur. However, the soluble polysulfides Li
S
(4 ≤ x ≤ 8) produced during the discharge process can cause the so-called "shuttle effect" and lead to low coulombic efficiency and rapid capacity fading of the batteries, which seriously restrict their practical application. Using porous materials as hosts to immobilize the polysulfides is proved to be an effective strategy. In this article, a dual functional cage-like metal-organic framework (Cu-MOF), Cu-TDPAT, combining the Lewis basic sites from the nitrogen atoms of the ligand H
TDPAT with the Lewis acidic sites from Cu(ii) open metal sites (OMSs), was employed as the sulfur host in a Li-S battery for lithium ions and polysulfide anions (S
). In addition, the size of nano-Cu-TDPAT was also optimized by microwave synthesis to reduce the internal resistance of the batteries. The electrochemical test results showed that the optimized Cu-TDPAT material can efficiently confine the polysulfides within the MOF, and the resultant porous S@Cu-TDPAT composite cathode material with the size of 100 nm shows good cycling performance with a reversible capacity of about 745 mA h g
at 1C (1C = 1675 mA g
) after 500 cycles, to the best of our knowledge, which is higher than those of all reported S@MOF cathode materials. The DFT calculation and XPS data indicate that the good cycling performance mainly results from the dual functional binding sites (that is, Lewis acid and base sites) in nanoporous Cu-TDPAT, providing the comprehensive and robust interaction with the polysulfides to overcome their dissolution and diffusion into the electrolyte. Clearly, our work provides a good example of designing MOFs with suitable interaction sites for the polysulfides to achieve S@MOF cathode materials with excellent cycling performance by multiple synergistic effects between nanoporous host MOFs and the polysulfides.
An ultrasensitive photoelectrochemical method for achieving real‐time detection of single nanoparticle collision events is presented. Using a micrometer‐thick nanoparticulate TiO2‐filmed Au ...ultra‐microelectrode (TiO2@Au UME), a sub‐millisecond photocurrent transient was observed for an individual N719‐tagged TiO2 (N719@TiO2) nanoparticle and is due to the instantaneous collision process. Owing to a trap‐limited electron diffusion process as the rate‐limiting step, a random three‐dimensional diffusion model was developed to simulate electron transport dynamics in TiO2 film. The combination of theoretical simulation and high‐resolution photocurrent measurement allow electron‐transfer information of a single N719@TiO2 nanoparticle to be quantified at single‐molecule accuracy and the electron diffusivity and the electron‐collection efficiency of TiO2@Au UME to be estimated. This method provides a test for studies of photoinduced electron transfer at the single‐nanoparticle level.
Single‐nanoparticle photoelectrochemistry: A phototelectrochemical method is used for quantifying the electron transfer of a single N719@TiO2 nanoparticle and evaluating the nanostructured TiO2 film by experiment and simulation. These results provide new insights to facilitate the fabrication of photoelectrochemical devices with better performance.
The nanoparticle‐based electrocatalysts’ performance is directly related to their working conditions. In general, a number of nanoparticles are uncontrollably fixed on a millimetre‐sized electrode ...for electrochemical measurements. However, it is hard to reveal the maximum electrocatalytic activity owing to the aggregation and detachment of nanoparticles on the electrode surface. To solve this problem, here, we take the hydrogen evolution reaction (HER) catalyzed by palladium nanoparticles (Pd NPs) as a model system to track the electrocatalytic activity of single Pd NPs by stochastic collision electrochemistry and ensemble electrochemistry, respectively. Compared with the nanoparticle fixed working condition, Pd NPs in the nanoparticle diffused working condition results in a 2–5 orders magnitude enhancement of electrocatalytic activity for HER at various bias potential. Stochastic collision electrochemistry with high temporal resolution gives further insights into the accurate study of NPs’ electrocatalytic performance, enabling to dramatically enhance electrocatalytic efficiency.
Stochastic collision model: A carbon ultramicroelectrode (C‐UME) is used to obtain a 2–5 orders magnitude enhancement of maximum turnover frequency (kcat) by stochastic collision electrochemistry compared with the ensemble electrochemistry. The electrocatalytic activity of nanoparticle‐based electrocatalysts is directly related to their working conditions, and the electrocatalytic heterogeneity among palladium nanoparticles (Pd NPs) could be displayed by stochastic collision electrochemistry.
