Carbon‐based heteroatom‐coordinated single‐atom catalysts (SACs) are promising candidates for energy‐related electrocatalysts because of their low‐cost, tunable catalytic activity/selectivity, and ...relatively homogeneous morphologies. Unique interactions between single metal sites and their surrounding coordination environments play a significant role in modulating the electronic structure of the metal centers, leading to unusual scaling relationships, new reaction mechanisms, and improved catalytic performance. This review summarizes recent advancements in engineering of the local coordination environment of SACs for improved electrocatalytic performance for several crucial energy‐convention electrochemical reactions: oxygen reduction reaction, hydrogen evolution reaction, oxygen evolution reaction, CO2 reduction reaction, and nitrogen reduction reaction. Various engineering strategies including heteroatom‐doping, changing the location of SACs on their support, introducing external ligands, and constructing dual metal sites are comprehensively discussed. The controllable synthetic methods and the activity enhancement mechanism of state‐of‐the‐art SACs are also highlighted. Recent achievements in the electronic modification of SACs will provide an understanding of the structure–activity relationship for the rational design of advanced electrocatalysts.
Carbon‐based heteroatom‐coordinated single‐atom catalysts are promising candidates for energy‐conversion related electrocatalysts. This review summarizes the recent advancements in the engineering of carbon‐based heteroatom‐coordinated single metal site catalysts for energy‐related electrochemical reactions, including the oxygen reduction reaction, hydrogen evolution reaction, oxygen evolution reaction, CO2 reduction reaction, and nitrogen reduction reaction.
The electrochemical CO2 reduction reaction (CO2RR) is a promising strategy to achieve electrical‐to‐chemical energy storage while closing the global carbon cycle. The carbon‐supported single‐atom ...catalysts (SACs) have great potential for electrochemical CO2RR due to their high efficiency and low cost. The metal centers’ performance is related to the local coordination environment and the long‐range electronic intercalation from the carbon substrates. This review summarizes the recent progress on the synthesis of carbon‐supported SACs and their application toward electrocatalytic CO2 reduction to CO and other C1 and C2 products. Several SACs are involved, including MNx catalysts, heterogeneous molecular catalysts, and the covalent organic framework (COF) based SACs. The controllable synthesis methods for anchoring single‐atom sites on different carbon supports are introduced, focusing on the influence that precursors and synthetic conditions have on the final structure of SACs. For the CO2RR performance, the intrinsic activity difference of various metal centers and the corresponding activity enhancement strategies via the modulation of the metal centers’ electronic structure are systematically summarized, which may help promote the rational design of active and selective SACs for CO2 reduction to CO and beyond.
This review summarizes the recent work on the synthesis of carbon‐supported single‐atom catalysts (SACs) and their application in electrochemical CO2 reduction to produce CO and other C1 and C2 products. Several different types of carbon‐supported SACs are involved, including MNx catalysts, heterogeneous molecular catalysts, and the covalent organic frameworks (COFs) based single atoms.
We applied black phosphorene (BP) and hexagonal boron nitride (BN) nanosheets as flame retardants to waterborne polyurethane to fabricate a novel black phosphorus/boron nitride/waterborne ...polyurethane composite material. The results demonstrated that the limiting oxygen index of the flame-retarded waterborne polyurethane composite increased from 21.7% for pure waterborne polyurethane to 33.8%. The peak heat release rate and total heat release of the waterborne polyurethane composite were significantly reduced by 50.94% and 23.92%, respectively, at a flame-retardant content of only 0.4 wt%. The superior refractory performances of waterborne polyurethane composite are attributed to the synergistic effect of BP and BN in the gas phase and condensed phase. This study shows that black phosphorus-based nanocomposites have great potential to improve the fire resistance of polymers.
Compared with skyrmions in ferromagnetic (FM) materials, skyrmions in near-compensated ferrimagnetic (FIM) materials demonstrate higher motion velocity and negligible skyrmion Hall (Sky-Hall) angle. ...This provides a brighter prospect of skyrmions for computing applications. In this letter, we propose an FIM skyrmion-based ultra-low power electric-field-controlled reconfigurable (SUPER) logic gate. By leveraging electric-field-controlled magnetic anisotropy (EFCMA) effect and skyrmion-skyrmion (Sky-Sky) interaction, varied logic functions, such as AND, OR, XOR, NOT, etc., can be realized. Moreover, artificial fishtail-shaped hollows are introduced for implementing skyrmion divisions. Micromagnetic simulations have been performed to validate the logic operations and divisions. By combining these mechanisms, an ultra-low power parallel computing scheme based on FIM skyrmions is proposed, in which multiple logic operations of two inputs can be carried out in parallel. The influence of the number of logic operations on energy consumption improvement has been investigated.
Single‐atom catalysts (SACs) on 2D nanomaterials have great potential as efficient and low‐cost electrocatalysts for clean energy technologies. The coordination environments, as well as the ...physicochemical properties of the 2D supports, play key roles in tuning the catalytic activity and reaction mechanism of the single‐atom centers. This review first summarizes the suitable synthetic strategies of single‐atom on different 2D supports. The methods that facilitate the formation of relative homogeneous structure and enable the regulation of the surrounding atomic environment of metal center are discussed. Furthermore, the recent progress of SACs for energy‐related electrochemical applications is reviewed, including oxygen reduction reaction, hydrogen evolution reaction, oxygen evolution reaction, CO2 reduction reaction, and nitrogen reduction reaction. The strategies about modulation of the electronic structure of single‐atom for enhanced performance are highlighted, together with a discussion of the current issues and the prospects of this field.
The synthetic strategies, electronic modulation process, and energy‐related electrochemical applications of single‐atom catalysts on different 2D supports are reviewed. Works about modulation of the electronic structure for enhanced performance are highlighted. The applications involve oxygen reduction reaction (ORR), hydrogen evolution reaction (HER), oxygen evolution reaction (OER), CO2 reduction reaction (CO2RR), and nitrogen reduction reaction (NRR).
Micro-channels in porous aluminum fabricated by the NaCl space holder method has been studied for the first time in this work. According to the material fabrication characteristics, the influence of ...two sets of technological processes and five kinds of process parameters was studied. The dissolution rate of NaCl particles was used to characterize the state of micro-channels indirectly and wholly and combined with the traditional direct and regional characterization methods to conduct a comprehensive study. It was found that there were three types of micro-channels in the fabrication process: gap-micro-channel, crack-micro-channel, and reticulation-micro-channel. The three types of micro-channels had significant differences in size and quantity and presented various states in different processes. Moreover, the participation of NaCl in sintering inhibited the formation of reticulation-micro-channels but promoted the formation and development of gap-micro-channels and crack-micro-channels. The NaCl particle content and size, sintering temperature, and compaction pressure can affect the micro-channels, but the sintering time cannot.
Porous TiAl3 intermetallics were prepared by the thermal explosion (TE) and space holder method with different particle sizes of Ti and Al powders, and their reaction behaviors were investigated. The ...results showed that with the increase in the particle size of the Ti and Al powders, the interfacial contact between the particles decreased, resulting in low interfacial energy and reaction activity, making the process difficult to initiate. Meanwhile, the heat flow rose from 358.37 J/g to 730.17 J/g and 566.74 J/g due to the extension of the solid–liquid diffusion time. The TiAl3 structures obviously expanded, and the formation of connected pore channels promoted the porosity. Only when the Ti and Al particle sizes were both small did the solid–solid diffusion significantly appear. At the same time, the TE reaction weakened, so the product particles had no time to fully grow. This indicates that the particle size of the raw materials controlled the TE reaction process by changing the solid–liquid diffusion reaction time and the degree of solid-phase diffusion.
In this study, the Ti-Al-Si + xTiC (x = 0, 2, 6, 10 wt.%) composite coatings, each with a different content of TiC were fabricated on a Ti-6Al-4V alloy by laser surface cladding. The microstructure ...of the prepared coatings was analyzed by the scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD). The microhardness and the wear resistance of these coatings were also evaluated. The results show that α-Ti, Ti3Al, Ti5Si3, TiAl3, TiAl, Ti3AlC2 and TiC particles can be found in the composites. The microstructure can obviously be refined by increasing the content of TiC particles, while the microhardness increases and the coefficient of friction decreases. The Ti-Al-Si-6TiC composite shows the best wear resistance, owing to its relatively fine microstructure and high content of TiC particles. The microhardness of this coating is 5.3 times that of the substrate, while the wear rate is only 0.43 times. However, when the content of TiC was up to 10 wt.%, the original TiC could not be dissolved completely during the laser cladding process, leading to formation of cracks on the coatings.
Nitrogen (N) availability is a critical factor for plant development and crop yield, and it closely correlates to carbon (C) metabolism. Uncoupling protein (UCP) and alternative oxidase (AOX) exhibit ...a strong correlation with N and C metabolism. Here, we investigated the functions of UCP1 and AOX1a using their mutants and complementation lines in Arabidopsis adaptation to low N. Low N markedly increased
AOX1a
and
UCP1
expression, alternative pathway capacity and UCP activity. Eight-day-old
aox1a/ucp1
seedlings were more sensitive to low N than Col-0 and single mutants, exhibiting lower primary root length and higher anthocyanin accumulation. The net photosynthetic rate, electron transport rate, PSII actual photochemical efficiency, stomatal conductance and carboxylation efficiency were markedly decreased in
ucp1
and
aox1a
/
ucp1
compared to those in Col-0 and
aox1a
under low N stress; comparatively, chlorophyll content and non-photochemical quenching coefficient were the lowest and highest in
aox1a
/
ucp1
, respectively. Nitrate acquisition rate was accelerated in
aox1a/ucp1
, but its transport activity was decreased, which resulted in low nitrate content and nitrate reductase activity under low N condition. The C/N ratio in seeds, but not in leaves, is higher in
aox1a
/
ucp1
than that in Col-0,
aox1a
and
ucp1
under low N condition. RNA-seq analysis revealed that many genes involved in photosynthesis and C/N metabolism were markedly down-regulated in
aox1a/ucp1
under low N stress. These results highlight the key roles of
UCP1
and
AOX1a
in modulating photosynthetic capacity, C/N assimilation and distribution under low N stress.
This paper studies the role of B2O3 in the radiation shielding properties of (100-x)(60TeO2-40PbO)-xB2O3 glass systems where x = 0, 1, 2, 3, 4 and 5 mol%. Through the scanning electron microscope ...(SEM) and X-ray diffraction (XRD) tests of the glass, the structure of the glass was studied. Physical radiation sources (57Co, 60Co, 137Cs, 133Ba, and 241Am) and WinXCOM software were used to experimentally and theoretically calculate the radiation properties of the glass, respectively. The gamma shielding ability of the glass was evaluated using its mass decay coefficient (μm), half-value layer (HVL), mean free path (MFP) and effective atomic number (Zeff). The neutron shielding ability of the glass was evaluated by calculating the fast neutron removal cross-section (RCS) value. The glass’s gamma and neutron shielding properties were compared to various ordinary concrete and other tellurite glasses. The measured mass decay coefficients agree well with the theoretical values obtained using WinXCOM software. Low HVL, MFP, and high μm, Zeff, and RCS values indicate that this series of glass materials have good shielding properties. According to the obtained results, among the glass samples doped with B2O3, the TPB-1 glass sample showed the best radiation shielding performance.
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