Conspectus Nanozymes, which integrate the advantages of both nanomaterials and natural enzymes, have accumulated enormous research interest over the past decades because of the opportunity they ...provide to appreciate and further cultivate artificial enzymes with comparable properties. By mimicking the coordination environments of the catalytic sites in natural enzymes, nanozymes with confined nanostructures can serve as substitutes in many catalytic processes with comparable activity and robust stability even in harsh conditions. Since the pioneering report about peroxidase-mimicking ferromagnetic nanoparticles in 2007, nanozymes have been developed as specialized for nanomaterials with intrinsic enzyme-mimicking property. With the rapid development in nanoscience and nanotechnology, nanomaterials with superior advantages, such as large-scale production, desired activity, and robust stability, can bridge the natural enzymes with nanozymes. Metal–organic frameworks (MOFs) and their derivatives hold great promise to serve as direct surrogates of conventional enzymes for enzymatic reactions. According to their chemical nature, MOF-based nanozymes can be divided into three main categories: pristine MOFs, enzyme-encapsulated MOF composites, and MOF-based derivatives. Due to the versatility of metallic nodes and bridging linkers together with the feasibility of postsynthetic engineering and modification, MOFs and their derivatives are envisioned as one of the most appropriate surrogates for this purpose. Using MOFs as precursors or sacrificial templates, multiple MOF-based derivatives including carbon-based nanomaterials (e.g., heteroatom-doped carbon or carbon with M–N–C moiety), metal oxide/carbon nanoparticles, and metal/carbon nanomaterials can be rationally synthesized through one-step direct carbonization/oxidation or indirect post-synthesis treatments of MOFs (e.g., bridging linker-exchange and metallic node-doping). Compared with existing nanozymes, MOF-based derivatives open up a new avenue for constructing mesoporous nanozymes. In this way, the intrinsic mesoporous properties of MOFs can still be maintained, while the stability and activity can be greatly improved. In this Account, we highlight some important research advances in MOF-based derivatives (including M–N–C moieties (M = single metal atom), metal oxide/carbon, metal/carbon, and MOF derivatives obtained through postsynthetic linker exchange and metal doping strategies) with enzyme-mimicking activity. We also demonstrate that, through integrating physicochemical properties of mesoporous nanomaterials and enzymatic activities of natural enzymes, MOF-derived nanozymes can provide multifunctional platforms in biomedical fields such as antibacterial agents, biosensors, imaging, cancer therapy, and environmental protection. Finally, we propose future design principles and possible research approaches for deeper understanding of mechanisms, thus pointing out future research directions to offer more opportunities for the conventional enzyme-engineering industry.
High‐entropy alloys (HEAs) are expected to function well as electrocatalytic materials, owing to their widely adjustable composition and unique physical and chemical properties. Recently, HEA ...catalysts are extensively studied in the field of electrocatalysis; this motivated the authors to investigate the relationship between the structure and composition of HEAs and their electrocatalytic performance. In this review, the latest advances in HEA electrocatalysts are systematically summarized, with special focus on nitrogen fixation, the carbon cycle, water splitting, and fuel cells; in addition, by combining this with the characterization and analysis of HEA microstructures, rational design strategies for optimizing HEA electrocatalysts, including controllable preparation, component regulation, strain engineering, defect engineering, and theoretical prediction are proposed. Moreover, the existing issues and future trends of HEAs are predicted, which will help further develop these high‐entropy materials.
In this review, the latest advances in high‐entropy alloy (HEA) electrocatalysts for electrochemical energy storage and conversion are systematically summarized. Moreover, combining the characterization and analysis of HEA microstructures, rational design strategies are proposed for optimizing HEAs electrocatalysts, covering controllable preparation, component regulation, strain engineering, defect engineering, and theoretical prediction.
The reasonable design of electrode materials for rechargeable batteries plays an important role in promoting the development of renewable energy technology. With the in‐depth understanding of the ...mechanisms underlying electrode reactions and the rapid development of advanced technology, the performance of batteries has significantly been optimized through the introduction of defect engineering on electrode materials. A large number of coordination unsaturated sites can be exposed by defect construction in electrode materials, which play a crucial role in electrochemical reactions. Herein, recent advances regarding defect engineering in electrode materials for rechargeable batteries are systematically summarized, with a special focus on the application of metal‐ion batteries, lithium–sulfur batteries, and metal–air batteries. The defects can not only effectively promote ion diffusion and charge transfer but also provide more storage/adsorption/active sites for guest ions and intermediate species, thus improving the performance of batteries. Moreover, the existing challenges and future development prospects are forecast, and the electrode materials are further optimized through defect engineering to promote the development of the battery industry.
Recent advances regarding defect engineering on electrode materials for rechargeable batteries are systematically summarized, with a special focus on application in metal‐ion batteries, lithium–sulfur batteries, and metal–air batteries. The defects can not only promote diffusion of ions and charge transfer, but also maintain structural stability and provide more energy storage/adsorption/active sites, thus improving the performance of the batteries.
The commercialization of fuel cells, such as proton exchange membrane fuel cells and direct methanol/formic acid fuel cells, is hampered by their poor stability, high cost, fuel crossover, and the ...sluggish kinetics of platinum (Pt) and Pt‐based electrocatalysts for both the cathodic oxygen reduction reaction (ORR) and the anodic hydrogen oxidation reaction (HOR) or small molecule oxidation reaction (SMOR). Thus far, the exploitation of active and stable electrocatalysts has been the most promising strategy to improve the performance of fuel cells. Accordingly, increasing attention is being devoted to modulating the surface/interface electronic structure of electrocatalysts and optimizing the adsorption energy of intermediate species by defect engineering to enhance their catalytic performance. Defect engineering is introduced in terms of defect definition, classification, characterization, construction, and understanding. Subsequently, the latest advances in defective electrocatalysts for ORR and HOR/SMOR in fuel cells are scientifically and systematically summarized. Furthermore, the structure–activity relationships between defect engineering and electrocatalytic ability are further illustrated by coupling experimental results and theoretical calculations. With a deeper understanding of these complex relationships, the integration of defective electrocatalysts into single fuel‐cell systems is also discussed. Finally, the potential challenges and prospects of defective electrocatalysts are further proposed, covering controllable preparation, in situ characterization, and commercial applications.
The latest advances in the development of fuel‐cell electrocatalysts by defect engineering are systematically introduced. Such defects modulate electronic structure and improve electrical conductivity, consequently enhancing the activities of electrocatalysts.
Metallic Zn as a promising anode material of aqueous batteries suffers from severe parasitic reactions and notorious dendrite growth. To address these issues, the desolvation and nucleation processes ...need to be carefully regulated. Herein, Zn foils coated by ZnF2–Ag nanoparticles (ZnF2–Ag@Zn) are used as a model to modulate the desolvation and nucleation processes by hybrid surfaces, where Ag has a strong affinity to Zn adatoms and ZnF2 shows an intense adsorption to H2O. This selective adsorption of different species on ZnF2 and Ag reduces the mutual interference between two species. Therefore, ZnF2–Ag@Zn exhibits the electrochemical performance much better than ZnF2@Zn or Ag@Zn. Even at −40 °C, the full cells using ZnF2–Ag@Zn demonstrate an ultralong lifespan of 5000 cycles with a capacity retention of almost 100%. This work provides new insights to improve the performance of Zn metal batteries, especially at low temperatures.
As a major component of cell membrane lipids, Arachidonic acid (AA), being a major component of the cell membrane lipid content, is mainly metabolized by three kinds of enzymes: cyclooxygenase (COX), ...lipoxygenase (LOX), and cytochrome P450 (CYP450) enzymes. Based on these three metabolic pathways, AA could be converted into various metabolites that trigger different inflammatory responses. In the kidney, prostaglandins (PG), thromboxane (Tx), leukotrienes (LTs) and hydroxyeicosatetraenoic acids (HETEs) are the major metabolites generated from AA. An increased level of prostaglandins (PGs), TxA
and leukotriene B4 (LTB
) results in inflammatory damage to the kidney. Moreover, the LTB
-leukotriene B4 receptor 1 (BLT1) axis participates in the acute kidney injury via mediating the recruitment of renal neutrophils. In addition, AA can regulate renal ion transport through 19-hydroxystilbenetetraenoic acid (19-HETE) and 20-HETE, both of which are produced by cytochrome P450 monooxygenase. Epoxyeicosatrienoic acids (EETs) generated by the CYP450 enzyme also plays a paramount role in the kidney damage during the inflammation process. For example, 14 and 15-EET mitigated ischemia/reperfusion-caused renal tubular epithelial cell damage. Many drug candidates that target the AA metabolism pathways are being developed to treat kidney inflammation. These observations support an extraordinary interest in a wide range of studies on drug interventions aiming to control AA metabolism and kidney inflammation.
Surface Solar Irradiance (SSI) is a key parameter dictating surface-atmosphere interactions, driving radiative, hydrological, and land surface processes, and can thus impinge greatly upon weather and ...climate. It is thereby a prerequisite of many studies and applications. Estimating SSI from satellites began in the 1960s, and is currently the principal way to map SSI spatiotemporal distributions from regional to global scales. Starting from an overview of historical studies carried out in the past several decades, this paper reviews the progresses made in methodology, validation, and products over these years. First, the requirements of SSI in various studies or applications are presented along with the theoretical background of SSI satellite estimation. Methods to estimate SSI from satellites are then summarized as well as their advantages and limitations. Validations of satellite-based SSI on two typical spatial scales are discussed followed by a brief description of existing products and their accuracies. Finally, the challenges faced by current SSI satellite estimation are analyzed, and possible improvements to implement in the future are suggested. This review not only updates the review paper by Pinker et al. (1995) on satellite methods to derive SSI but also offers a more comprehensive summary of the related studies and applications.
•A comprehensive review of estimating SSI from satellites is presented.•Methods, validations, and products from the past few decades are reviewed.•Current challenges and future directions are suggested.
Functional materials displaying tunable emission and long-lived luminescence have recently emerged as a powerful tool for applications in information encryption, organic electronics and ...bioelectronics. Herein, we present a design strategy to achieve color-tunable ultralong organic room temperature phosphorescence (UOP) in polymers through radical multicomponent cross-linked copolymerization. Our experiments reveal that by changing the excitation wavelength from 254 to 370 nm, these polymers display multicolor luminescence spanning from blue to yellow with a long-lived lifetime of 1.2 s and a maximum phosphorescence quantum yield of 37.5% under ambient conditions. Moreover, we explore the application of these polymers in multilevel information encryption based on the color-tunable UOP property. This strategy paves the way for the development of multicolor bio-labels and smart luminescent materials with long-lived emission at room temperature.
The therapeutic effect of reactive oxygen species (ROS)-involved cancer therapies is significantly limited by shortage of oxy-substrates, such as hypoxia in photodynamic therapy (PDT) and ...insufficient hydrogen peroxide (H
O
) in chemodynamic therapy (CDT). Here, we report a H
O
/O
self-supplying nanoagent, (MSNs@CaO
-ICG)@LA, which consists of manganese silicate (MSN)-supported calcium peroxide (CaO
) and indocyanine green (ICG) with further surface modification of phase-change material lauric acid (LA). Under laser irradiation, ICG simultaneously generates singlet oxygen and emits heat to melt the LA. The exposed CaO
reacts with water to produce O
and H
O
for hypoxia-relieved ICG-mediated PDT and H
O
-supplying MSN-based CDT, acting as an open source strategy for ROS production. Additionally, the MSNs-induced glutathione depletion protects ROS from scavenging, termed reduce expenditure. This open source and reduce expenditure strategy is effective in inhibiting tumor growth both in vitro and in vivo, and significantly improves ROS generation efficiency from multi-level for ROS-involved cancer therapies.
The nitrogenous nucleophile electrooxidation reaction (NOR) plays a vital role in the degradation and transformation of available nitrogen. Focusing on the NOR mediated by the β‐Ni(OH)2 electrode, we ...decipher the transformation mechanism of the nitrogenous nucleophile. For the two‐step NOR, proton‐coupled electron transfer (PCET) is the bridge between electrocatalytic dehydrogenation from β‐Ni(OH)2 to β‐Ni(OH)O, and the spontaneous nucleophile dehydrogenative oxidation reaction. This theory can give a good explanation for hydrazine and primary amine oxidation reactions, but is insufficient for the urea oxidation reaction (UOR). Through operando tracing of bond rupture and formation processes during the UOR, as well as theoretical calculations, we propose a possible UOR mechanism whereby intramolecular coupling of the N−N bond, accompanied by PCET, hydration and rearrangement processes, results in high performance and ca. 100 % N2 selectivity. These discoveries clarify the evolution of nitrogenous molecules during the NOR, and they elucidate fundamental aspects of electrocatalysis involving nitrogen‐containing species.
During urea electrooxidation over a Ni(OH)2 electrode the dehydrogenation reaction from β‐Ni(OH)2 to β‐Ni(OH)O can lead to spontaneous urea dehydrogenation. Spontaneous intramolecular coupling of the N−N bond and hydration of urea dehydrogenation intermediates play important roles in the oxidation path from urea to N2 and CO2.
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