Two-dimensional (2D) materials are characterised by their strong intraplanar bonding but weak interplanar interaction. Interfaces between neighboring 2D layers or between 2D overlayers and substrate ...surfaces provide intriguing confined spaces for chemical processes, which have stimulated a new area of "
chemistry under 2D cover
". In particular, well-defined 2D material overlayers such as graphene, hexagonal boron nitride, and transition metal dichalcogenides have been deposited on solid surfaces, which can be used as model systems to understand the new chemistry. In the present review, we first show that many atoms and molecules can intercalate ultrathin 2D materials supported on solid surfaces and the space under the 2D overlayers has been regarded as a 2D nanocontainer. Moreover, chemical reactions such as catalytic reactions, surface adlayer growth, chemical vapor deposition, and electrochemical reactions occur in the 2D confined spaces, which further act as 2D nanoreactors. It has been demonstrated that surface chemistry and catalysis are strongly modulated by the 2D covers, resulting in weakened molecule adsorption and enhanced surface reactions. Finally, we conclude that the confinement effect of the 2D cover leads to new chemistry in a small space, such as "catalysis under cover" and "electrochemistry under cover". These new concepts enable us to design advanced nanocatalysts encapsulated with 2D material shells which may present improved performance in many important processes of heterogeneous catalysis, electrochemistry, and energy conversion.
Interfaces between 2D material overlayers and solid surfaces provide confined spaces for chemical processes, which have stimulated new chemistry under a 2D cover.
The use of formic acid (FA) to produce molecular H2 is a promising means of efficient energy storage in a fuel‐cell‐based hydrogen economy. To date, there has been a lack of heterogeneous catalyst ...systems that are sufficiently active, selective, and stable for clean H2 production by FA decomposition at room temperature. For the first time, we report that flexible pyridinic‐N‐doped carbon hybrids as support materials can significantly boost the efficiency of palladium nanoparticle for H2 generation; this is due to prominent surface electronic modulation. Under mild conditions, the optimized engineered Pd/CN0.25 catalyst exhibited high performance in both FA dehydrogenation (achieving almost full conversion, and a turnover frequency of 5530 h−1 at 25 °C) and the reversible process of CO2 hydrogenation into FA. This system can lead to a full carbon‐neutral energy cycle.
Pyridinic‐N‐tuned catalysis: An electron‐rich pyridinic‐N dopant modulates the electronic interactions between the active sites of palladium nanoparticles and the carbon support. Formic acid dehydrogenation at room temperature is significantly boosted by the pyridinic‐N‐doped palladium catalyst, presenting an efficient and reliable route to clean H2 generation and sustainable energy storage.
Substrate‐supported metal–organic frameworks (MOFs) films are desired to realize their potential in practical applications. Herein, a novel substrate‐seeding secondary‐growth strategy is developed to ...prepare composites of uniform MOFs films on aerogel walls. Briefly, the organic ligand is “pre‐seeded” onto the aerogel walls, and then a small amount of metal‐ion solution is sprayed onto the prepared aerogel. The sprayed solution diffuses along the aerogel walls to form a continuous thin layer, which confines the nucleation reaction, promoting the formation of uniform MOFs films on the aerogel walls. The whole process is simple in operation, highly efficient, and eco‐friendly. The resulting hierarchical MOFs/aerogel composites have abundant accessible active sites and enable excellent mass transfer, which endows the composite with outstanding catalytic activity and stability in both liquid‐phase CO2 cycloaddition and electrochemical oxygen evolution reaction (OER) process.
Metal–organic framework (MOF) thin films are coated onto the walls of aerogel giving MOFs/aerogel composites. These have abundant accessible active sites and excellent mass transfer ability, and thus a relatively high catalytic activity and stability in the CO2 cycloaddition and oxygen evolution reaction (OER).
•Key contents and properties of algal suspension including cells and AOM are addressed.•MF and UF fouling by algal cells and AOM are compared, with cell growth discussed.•Control strategies via ...pretreating feedwater for algal fouling are reviewed.•Optimization of membrane properties and hydrodynamic conditions are provided.
Microalgae are ubiquitous in aquatic systems and are a highly diversified group of uni- and multicellular microorganisms. In low pressure-driven membrane systems, these cells and their secretions have a strong tendency to foul membranes and lead to a very low filtration efficiency. A significant amount of investigation on algal fouling of microfiltration (MF) and ultrafiltration (UF) membranes has been conducted in recent years. In this paper, recent knowledge of both MF and UF membrane fouling by microalgal suspensions, including the mechanisms and factors influencing algal fouling control strategies, is reviewed. The main components and properties of microalgae suspension are summarized. As algal cells and algogenic organic matter (AOM) are major foulants in microalgae suspension, their roles in algal fouling are compared and critically assessed. Based on the fouling mechanisms of these cells and AOM, strategies for mitigation of algal fouling are provided in detail, including pretreating feedwater, changing membrane properties, and enhancing hydrodynamic conditions. The breakup and growth of cells and their consequential influences on fouling receive special attention. Finally, useful directions for further work on MF and UF algal fouling are indicated.
According to the measurement uncertainty requirements of the key parameters of the declared tolerances of the products in the industrial standards of respiratory therapy equipment such as GB ...9706.212-2020
, YY 9706.270-2021
, and YY 9706.274-2022
, this study introduces and analyzes the evaluation process of the uncertainty of the key parameters of critical care respiratory, sleep apnoea breathing therapy equipment, and humidifier, and it gives the sources and results of measurement uncertainty. It is expected that it can provide suggestions for the medical device testing laboratory to meet the uncertainty requirements of quality management and provide references for relevant manufacturers to meet the requirements of industrial standards.
A solar thermoelectric generator (STEG) that generates electricity from sunlight is expected to be a promising technology for harvesting and conversion of clean solar energy. The integration of a ...phase-change material (PCM) with the STEG even more enables engines to durably generate power in spite of solar radiation flux. However, its photothermal conversion and output electricity is still limited (<15 W/m2) by the PCM’s deficient thermal management performance, i.e., restricted thermal conductivity and nonuniform heat-transfer behavior under concentrated sunlight radiation. In this study, a biomimetic phase-change composite, with centrosymmetric and a multidirectionally aligned boron nitride network embedded in polyethylene glycol, is tailored for the STEG via a radial ice-template assembly and infiltration strategy, which behaves in a highly and multidirectionally thermoconductive way and enables a rapid transfer of heat flux and uniform temperature distribution with respect to even a spot-like heat source. As a consequence, a powerful STEG is tactfully designed via the integration of this high-thermal-management characteristic and maximum collection of solar beams, for durable and real-environment solar–thermal–electric conversion, with its photothermal energy conversion efficiency of up to 85.1% and a high peak power density of 40.28 W/m2.
with the development of new media technology and the popularity of mobile devices, the short video platform has become one of the standing applications in the public’s mobile phones, and the short ...video tool has added a new color to the development of video shooting technology while enriching the spiritual and cultural life of the public. In the era of new media convergence, short video shooting technology has become an indispensable part of video shooting, in view of this, this paper mainly focuses on the analysis and research of short video photography technology under the integration of computer editing in the new media era.
In this work, we established a one-step strategy to synthesize three-dimensional porous graphitic biomass carbon (PGBC) from bamboo char (BC), and studied its electrochemical performance as electrode ...materials for supercapacitors. Using potassium ferrate (K 2 FeO 4 ) to fulfil the synchronous carbonization and graphitization of bamboo carbon, this method is less time-demanding, highly efficient and pollution-free, when compared with a conventional two-step strategy. The as-prepared PGBC sample possessed a porous structure with a large specific surface area (1732 m 2 g −1 ) and abundant micropores, as well as a high graphitization degree demonstrated by XRD and Raman. Further electrochemical measurements revealed that the PGBC electrode exhibited a high specific capacitance of 222.0 F g −1 at 0.5 A g −1 , and the solid-state symmetric supercapacitor in an aqueous electrolyte (KOH/PVA) presented considerable synergetic energy–power output properties with an energy density of 6.68 W h kg −1 at a power density of 100.2 W kg −1 , and 3.33 W h kg −1 at 10 kW kg −1 . Moreover, the coin-type symmetric supercapacitor in an ionic liquid electrolyte (EMIM TFSI) delivered a higher energy density of 20.6 W h kg −1 at a power density of 12 kW kg −1 . This approach holds great promise to achieve low-cost, green and industrial-grade production of renewable biomass-derived carbon materials for advanced energy storage applications in the future.
Lonicerae japonicae flos (called Jinyinhua, JYH in Chinese), flowers or flower buds of
Lonicera japonica
Thunberg, is an extremely used traditional edible-medicinal herb. Pharmacological studies have ...already proved JYH ideal clinical therapeutic effects on inflammation and infectious diseases and prominent effects on multiple targets in vitro and in vivo, such as pro-inflammatory protein inducible nitric oxide synthase, toll-like receptor 4, interleukin-1 receptor. JYH and Lonicerae flos called Shanyinhua, SYH in Chinese, flowers or flower buds of
Lonicera hypoglauca
Miquel,
Lonicera confusa
De Candolle or
Lonicera macrantha
(D.Don) Spreng which belongs to the same family of JYH were once recorded as same herb in multiple versions of Chinese Pharmacopoeia (ChP). However, they were listed as two different herbs in 2005 Edition ChP, leading to endless controversy since they have close proximity on plant species, appearances and functions, together with traditional applications. In the past decades, there has no literature regarding to systematical comparison on the similarity concerning research achievements of the two herbs. This review comprehensively presents similarities and differences between JYH and SYH retrospectively, particularly proposing them the marked differences in botanies, phytochemistry and pharmacological activities which can be used as evidence of separate list of JYH and SYH. Furthermore, deficiencies on present studies have also been discussed so as to further research could use for reference.
Confined microenvironments formed in heterogeneous catalysts have recently been recognized as equally important as catalytically active sites. Understanding the fundamentals of confined catalysis has ...become an important topic in heterogeneous catalysis. Well-defined 2D space between a catalyst surface and a 2D material overlayer provides an ideal microenvironment to explore the confined catalysis experimentally and theoretically. Using density functional theory calculations, we reveal that adsorption of atoms and molecules on a Pt(111) surface always has been weakened under monolayer graphene, which is attributed to the geometric constraint and confinement field in the 2D space between the graphene overlayer and the Pt(111) surface. A similar result has been found on Pt(110) and Pt(100) surfaces covered with graphene. The microenvironment created by coating a catalyst surface with 2D material overlayer can be used to modulate surface reactivity, which has been illustrated by optimizing oxygen reduction reaction activity on Pt(111) covered by various 2D materials. We demonstrate a concept of confined catalysis under 2D cover based on a weak van der Waals interaction between 2D material overlayers and underlying catalyst surfaces.
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