Nano Materials Science最新文献

2D-layered graphitic carbon nitride (g-C₃N₄) is regarded as a great prospect as a photocatalyst for H₂ generation. However, g-C₃N₄'s photocatalytic hydrogen evolution (HER) activity is significantly restricted by the recombination of photocarriers. We find that cobalt sulfide (CoS₂) as a cocatalyst can promote g-C₃N₄ nanosheets (NSs) to realize very efficient photocatalytic H₂ generation. The prepared CoS₂/g-C₃N₄ hybrids display highly boosted photocatalytic H₂ generation performance and outstanding cycle stability. The optimized 7%-CoS₂/g-C₃N₄ hybrids show a much improved photocatalytic H₂ generation rate of 36.2 ​μmol⁻¹ ​h⁻¹, which is about 180 times as much as bare g-C₃N₄ (0.2 ​μmol⁻¹ ​h⁻¹). In addition, the apparent quantum efficiency (AQE) of all the samples was computed under light at λ=370 ​nm, in which the AQE of 7%-CoS₂/g-C₃N₄ hybrids is up to 5.72%. The experimental data and the DFT calculation suggest that the CoS₂/g-C₃N₄ hybrid's excellent HER activity is attributable to the lower overpotential and the smaller Co-H bond activation energy for HER. Accordingly, the CoS₂ cocatalyst loading effectively boosts the photocatalytic performance of g-C₃N₄ for H₂ evolution. The project promotes fast development of high-efficiency photocatalysts and low-cost for photocatalytic H₂ generation.

Sulfur and selenium have been paid more and more attention in energy storage systems because of their high theoretical specific gravimetric and volumetric capacities. With the increasing scarcity of lithium resources, secondary batteries made of sulfur and selenium coupled with other alkali metal/alkaline earth metals (e.g. Na, K, Mg) are expected to play a vital role in future production and human life. Due to the volume expansion, poor conductivity and shuttle effect, the structure design of cathode, as one of the important roles in metal-S/Se batteries, has always been a hot and difficult point. In the review, various host materials of S and Se are clarified and discussed. Typically, carbonaceous materials are the most widely used hosts, while polar materials are becoming more and more popular in metal-S/Se batteries. Through a comprehensive overview, it is hoped that previous research experiences can provide further reference and guidance for the sustainable development of metal-S/Se batteries.

Yellow light-emitting diodes (LEDs) as soft light have attracted abundant attention in lithography room, museum and art gallery. However, the development of efficient yellow LEDs lags behind green and blue LEDs, and the available perovskites yellow LEDs suffer from the instability. Herein, a pressure-assisted cooling method is proposed to grow lead-free CsCu₂I₃ single crystals, which possess uniform surface morphology and enhanced photoluminescence quantum yield (PLQY) stability, with only 10% PLQY losses after being stored in air after 5000 ​h. Then, the single crystals used for yellow LEDs without encapsulation exhibit a decent Correlated Color Temperature (CCT) of 4290 ​K, a Commission Internationale de l'Eclairage (CIE) coordinate of (0.38, 0.41), and an excellent 570-h operating stability under heating temperature of 100 ​°C. Finally, the yellow LEDs facilitate the application in wireless visible light communication (VLC), which show a −3 dB bandwidth of 21.5 ​MHz and a high achievable data rate of 219.2 Mbps by using orthogonal frequency division multiplexing (OFDM) modulation with adaptive bit loading. The present work not only promotes the development of lead-free single crystals, but also inspires the potential of CsCu₂I₃ in the field of yellow illumination and wireless VLC.

The Chinese iron pan can function as a nonstick pan even without a polytetrafluoroethylene (PTFE) coating after a “Kitchen God blessing” seasoning process. We simulate this process and disclose the science behind the “Kitchen God blessing,” finding that through repeated oil-coating and heating, the reversible insertion and extraction of oxygen atoms split the surface of the iron pan, gradually producing Fe₃O₄ nanoballs. These balls give the iron pan a conditional hydrophobicity property, meaning the pan would be hydrophilic when the ingredients contain much water and hydrophobic when they contain less water. The former enables heat to be transferred rapidly through the nanoballs while the latter slows down the heat transference and prevents the pan from sticking. This discovery provides an approach of generating nanoballs on the surface of the metal and also discloses the secret of the fantastic taste produced by cooking with a Chinese iron pan.

Water splitting is an effective strategy to produce renewable and sustainable hydrogen energy. Especially, seawater splitting, avoiding use of the limited freshwater resource, is more intriguing. Nowadays, electrocatalysts explored for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) using natural seawater or saline electrolyte have been increasingly reported. To better understand the current status and challenges of the electrocatalysts for HER and OER from seawater, we comprehensively review the recent advances in electrocatalysts for seawater splitting. The fundamentals, challenges and possible strategies for seawater splitting are firstly presented. Then, the recently reported electrocatalysts that explored for HER and OER from seawater are summarized and discussed. Finally, the perspectives in the development of high-efficient electrocatalysts for seawater splitting are also proposed.

Two−dimensional (2D) supports confined single−atom catalysts (2D SACs) with unique geometric and electronic structures have been attractive candidates in different catalytic applications, such as energy conversion and storage, value−added chemical synthesis and environmental remediation. However, their environmental applications lack of a comprehensive summary and in−depth discussion. In this review, recent progresses in synthesis routes and advanced characterization techniques for 2D SACs are introduced, and a comprehensive discussion on their applications in environmental remediation is presented. Generally, 2D SACs can be effective in catalytic elimination of aqueous and gaseous pollutants via radical or non−radical routes and transformation of toxic pollutants into less poisonous species or highly value−added products, opening a new horizon for the contaminant treatment. In addition, in−depth reaction mechanisms and potential pathways are systematically discussed, and the relationship between the structure−performance is highlighted. Finally, several critical challenges within this field are presented, and possible directions for further explorations of 2D SACs in environmental remediation are suggested. Although the research of 2D SACs in the environmental application is still in its infancy, this review will provide a timely summary on the emerging field, and would stimulate tremendous interest for designing more attractive 2D SACs and promoting their wide applications.

Selective hydrogenation of phenol to cyclohexanone is intriguing in chemical industry. Though a few catalysts with promising performances have been developed in recent years, the basic principle for catalyst design is still missing owing to the unclear catalytic mechanism. This work tries to unravel the mechanism of phenol hydrogenation and the reasons causing the selectivity discrepancy on noble metal catalysts under mild conditions. Results show that different reaction pathways always firstly converge to the formation of cyclohexanone under mild conditions. The selectivity discrepancy mainly depends on the activity for cyclohexanone sequential hydrogenation, in which two factors are found to be responsible, i.e. the hydrogenation energy barrier and the competitive chemisorption between phenol and cyclohexanone, if the specific co-catalyzing effect of H₂O on Ru is not considered. Based on the above results, a quantitative descriptor, E_b(one/pl)/E_a, in which E_a can be further correlated to the d band center of the noble metal catalyst, is proposed by the first time to roughly evaluate and predict the selectivity to cyclohexanone for catalyst screening.

Ultra-high molecular weight polyethylene (UHMWPE) fiber is a new kind of high-performance fiber. Due to its excellent physical and chemical characteristics, it is widely used in various fields. However, the surface UHMWPE fiber is smooth and demonstrates no-polar groups. The weak interfacial adhesion between fiber and resin seriously restricts the applications of UHMWPE fiber. Therefore, the surface modification treatments of UHMWPE fiber are used to improve the interfacial adhesion strength. The modified method by adding nanomaterials elucidates the easy fabrication, advanced equipment and proper technology. Thus, the progress of UHMWPE nanocomposite fibers prepared via adding various nanofillers are reviewed. Meanwhile, the effects of other various methods on surface modification are also reviewed. This work advances the various design strategies about nano technologies on improving interfacial adhesion performance via treatment methodologies.

The additive manufacturing (AM) of Ni-based superalloys has attracted extensive interest from both academia and industry due to its unique capabilities to fabricate complex and high-performance components for use in high-end industrial systems. However, the intense temperature gradient induced by the rapid heating and cooling processes of AM can generate high levels of residual stress and metastable chemical and structural states, inevitably leading to severe metallurgical defects in Ni-based superalloys. Cracks are the greatest threat to these materials’ integrity as they can rapidly propagate and thereby cause sudden and non-predictable failure. Consequently, there is a need for a deeper understanding of residual stress and cracking mechanisms in additively manufactured Ni-based superalloys and ways to potentially prevent cracking, as this knowledge will enable the wider application of these unique materials. To this end, this paper comprehensively reviews the residual stress and the various mechanisms of crack formation in Ni-based superalloys during AM. In addition, several common methods for inhibiting crack formation are presented to assist the research community to develop methods for the fabrication of crack-free additively manufactured components.

MXenes are emerging transition metal carbides and nitrides-based 2D conductive materials. They have found wide applications in sensors due to their excellent valuable properties. This paper reviews the recent research status of MXene-based electrochemical (bio) sensors for detecting biomarkers, pesticides, and other aspects. The first part of this paper introduced the synthesis strategy and the effect of surface modification on various properties of MXenes. The second part of this paper discussed the application of MXenes as electrode modifiers for detecting pesticides, environmental pollutants, and biomarkers such as glucose, hydrogen peroxide, etc. Hope this review will inspire more efforts toward research on MXene-based sensors to meet the growing requirements.