Demonstrated here is the correlation between atomic configuration induced electronic density of single‐atom Co active sites and oxygen reduction reaction (ORR) performance by combining ...density‐functional theory (DFT) calculations and electrochemical analysis. Guided by DFT calculations, a MOF‐derived Co single‐atom catalyst with the optimal Co1‐N3PS active moiety incorporated in a hollow carbon polyhedron (Co1‐N3PS/HC) was designed and synthesized. Co1‐N3PS/HC exhibits outstanding alkaline ORR activity with a half‐wave potential of 0.920 V and superior ORR kinetics with record‐level kinetic current density and an ultralow Tafel slope of 31 mV dec−1, exceeding that of Pt/C and almost all non‐precious ORR electrocatalysts. In acidic media the ORR kinetics of Co1‐N3PS/HC still surpasses that of Pt/C. This work offers atomic‐level insight into the relationship between electronic density of the active site and catalytic properties, promoting rational design of efficient catalysts.
The correlation between atomic configuration induced electronic density of single‐atom Co active sites and oxygen reduction reaction (ORR) performance has been established by combining density‐functional theory calculations and electrochemical analysis. A metal–organic framework derived single‐atom Co catalyst, comprising an optimal Co1‐N3PS active moiety supported on hollow carbon polyhedron (Co1‐N3PS/HC), was synthesized, and it exhibits superior alkaline and acidic ORR performance.
Abstract
Atomic-level coordination engineering is an efficient strategy for tuning the catalytic performance of single-atom catalysts (SACs). However, their rational design has so far been plagued by ...the lack of a universal correlation between the coordination symmetry and catalytic properties. Herein, we synthesised planar-symmetry-broken CuN
3
(PSB-CuN
3
) SACs through microwave heating for electrocatalytic CO
2
reduction. Remarkably, the as-prepared catalysts exhibited a selectivity of 94.3% towards formate at −0.73 V vs. RHE, surpassing the symmetrical CuN
4
catalyst (72.4% at −0.93 V vs. RHE). In a flow cell equipped with a PSB-CuN
3
electrode, over 90% formate selectivity was maintained at an average current density of 94.4 mA cm
−2
during 100 h operation. By combining definitive structural identification with operando X-ray spectroscopy and theoretical calculations, we revealed that the intrinsic local symmetry breaking from planar
D
4
h
configuration induces an unconventional
dsp
hybridisation, and thus a strong correlation between the catalytic activity and microenvironment of metal centre (i.e., coordination number and distortion), with high preference for formate production in CuN
3
moiety. The finding opens an avenue for designing efficient SACs with specific local symmetries for selective electrocatalysis.
Current knowledge about the evolutionary history of donkeys is still incomplete due to the lack of archeological and whole-genome diversity data. To fill this gap, we have de novo assembled a ...chromosome-level reference genome of one male Dezhou donkey and analyzed the genomes of 126 domestic donkeys and seven wild asses. Population genomics analyses indicate that donkeys were domesticated in Africa and conclusively show reduced levels of Y chromosome variability and discordant paternal and maternal histories, possibly reflecting the consequences of reproductive management. We also investigate the genetic basis of coat color. While wild asses show diluted gray pigmentation (Dun phenotype), domestic donkeys display non-diluted black or chestnut coat colors (non-Dun) that were probably established during domestication. Here, we show that the non-Dun phenotype is caused by a 1 bp deletion downstream of the TBX3 gene, which decreases the expression of this gene and its inhibitory effect on pigment deposition.
Abstract
Grain boundary controlling is an effective approach for manipulating the electronic structure of electrocatalysts to improve their hydrogen evolution reaction performance. However, probing ...the direct effect of grain boundaries as highly active catalytic hot spots is very challenging. Herein, we demonstrate a general water-assisted carbothermal reaction strategy for the construction of ultrathin Mo
2
C nanosheets with high-density grain boundaries supported on N-doped graphene. The polycrystalline Mo
2
C nanosheets are connected with N-doped graphene through Mo–C bonds, which affords an ultra-high density of active sites, giving excellent hydrogen evolution activity and superior electrocatalytic stability. Theoretical calculations reveal that the
d
z
2
orbital energy level of Mo atoms is controlled by the MoC
3
pyramid configuration, which plays a vital role in governing the hydrogen evolution activity. The
d
z
2
orbital energy level of metal atoms exhibits an intrinsic relationship with the catalyst activity and is regarded as a descriptor for predicting the hydrogen evolution activity.
The W
1
Mo
1
-NG dual-atom catalyst enables Pt-like activity and ultrahigh stability for hydrogen evolution reaction.
Single-atom catalysts (SACs) maximize the utility efficiency of metal atoms and ...offer great potential for hydrogen evolution reaction (HER). Bimetal atom catalysts are an appealing strategy in virtue of the synergistic interaction of neighboring metal atoms, which can further improve the intrinsic HER activity beyond SACs. However, the rational design of these systems remains conceptually challenging and requires in-depth research both experimentally and theoretically. Here, we develop a dual-atom catalyst (DAC) consisting of O-coordinated W-Mo heterodimer embedded in N-doped graphene (W
1
Mo
1
-NG), which is synthesized by controllable self-assembly and nitridation processes. In W
1
Mo
1
-NG, the O-bridged W-Mo atoms are anchored in NG vacancies through oxygen atoms with W─O─Mo─O─C configuration, resulting in stable and finely distribution. The W
1
Mo
1
-NG DAC enables Pt-like activity and ultrahigh stability for HER in pH-universal electrolyte. The electron delocalization of W─O─Mo─O─C configuration provides optimal adsorption strength of H and boosts the HER kinetics, thereby notably promoting the intrinsic activity.
Photoelectrochemical water splitting has long been considered an ideal approach to producing green hydrogen by utilizing solar energy. However, the limited photocurrents and large overpotentials of ...the anodes seriously impede large-scale application of this technology. Here, we use an interfacial engineering strategy to construct a nanostructural photoelectrochemical catalyst by incorporating a semiconductor CdS/CdSe-MoS
and NiFe layered double hydroxide for the oxygen evolution reaction. Impressively, the as-prepared photoelectrode requires an low potential of 1.001 V vs. reversible hydrogen electrode for a photocurrent density of 10 mA cm
, and this is 228 mV lower than the theoretical water splitting potential (1.229 vs. reversible hydrogen electrode). Additionally, the generated current density (15 mA cm
) of the photoelectrode at a given overpotential of 0.2 V remains at 95% after long-term testing (100 h). Operando X-ray absorption spectroscopy revealed that the formation of highly oxidized Ni species under illumination provides large photocurrent gains. This finding opens an avenue for designing high-efficiency photoelectrochemical catalysts for successive water splitting.
•Prolonged saucing reduced the yield of chicken gizzards.•Ultrasound pretreatment improved the water holding capacity of saucing samples.•Ultrasound pretreatment could strengthen the flavor of ...saucing chicken gizzards.•Ultrasound technology effectively shortened the saucing time of chicken gizzards.
The purpose of this study was to evaluate the effects of ultrasound-assisted saucing on the quality of chicken gizzards. The results showed that with the prolonging of the saucing time, the yield, water holding capacity (WHC), lightness (L*), redness (a*) and springiness of chicken gizzards significantly decreased, while the shear force, hardness and chewiness significantly increased (P < 0.05). When the saucing time was the same, the yield, WHC, springiness and tenderness of the ultrasound group were significantly higher than those of the non-ultrasound group (P < 0.05). In particular, when the saucing time was 30 min, the yield, WHC and springiness of the ultrasound group increased by 2.13%, 0.97% and 10.53%, and the shear force decreased by 21.22% compared with those of the non-ultrasound group, respectively. Besides, ultrasound pretreatment increased the content of aromatic compounds, short-chain alkanes, alcohols, aldehydes and ketones, and the principal component analysis displayed that C-50 (saucing for 50 min without ultrasound pretreatment) and U-30 (saucing for 30 min with ultrasound pretreatment) were similar in flavor. Therefore, ultrasound pretreatment is a potential way to improve the quality of saucing chicken gizzards and shorten the processing time.
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•Ultrasound treatment promoted myofibril fragmentation of chicken gizzard.•Ultrasound treatment could weaken the degree of covalent cross-linking of collagen.•Ultrasound treatment ...reduced the thermal stability of chicken gizzard collagen.•500 W/30 min ultrasound treatment had the best tenderization effect.
The tenderizing effect of different ultrasound treatments on the characteristics of muscle fibers and connective tissue of chicken gizzard was investigated. It could be concluded that the shear force and muscle fiber diameter of the sample treated with ultrasound for 500 W/30 min were decreased by 27.1% and 26.2%, respectively, while the myofibril fragmentation index (MFI) was increased by 238.1% than the control. More importantly, the contents of hydroxylysine pyridinoline and lysine pyridinoline of the samples treated with ultrasound for 500 W/30 min were 23.1% and 40.5% lower than those of the control. Tenderizing effect of 500 W/30 min sample on thermal stability was verified from the decrease in transition temperature (Tmax) (10.7%) and enthalpy (ΔH) (21.7%) of collage compared with the control. In general, proper ultrasound treatment could effectively improve the tenderness of gizzard, and 500 W/30 min had the best tenderization effect. Therefore, the treatment of ultrasound was considered as a promising and efficient technique in meat processing, especially for the meat tenderization.
Abstract
Pressure-induced charge density wave (CDW) state can overcome the low-temperature limitation for practical application, thus seeking its traces in experiments is of great importance. Herein, ...we provide spectroscopic evidence for the emergence of room temperature CDW order in the narrow pressure range of 10–15 GPa in bulk VSe
2
. Moreover, we discovered an 8-coordination structure of VSe
2
with
C2/m
symmetry in the pressure range of 35–65 GPa by combining the X-ray absorption spectroscopy, X-ray diffraction experiments, and the first-principles calculations. These findings are beneficial for furthering our understanding of the charge modulated structure and its behavior under high pressure.
Extracellular acidosis is considered as a hallmark of most human tumors, which plays an important role in promoting tumor malignant and aggressive phenotype in tumorigenesis. Acidosis and lactic ...acidosis can induce different responses in tumors. Previous studies have associated the response to lactic acidosis of tumors with good survival outcomes. In this study, we investigated the metabolomic changes in triple negative and luminal subtype breast cancer cell lines in response to acidosis and lactic acidosis. Our results showed that acidosis results in the reduction of cell viability and glycolysis in breast cancer cells, which is reversely correlated with the malignancy of cell lines. Under lactic acidosis, this reduction is reversed slightly. Untargeted metabolomic profiling revealed that glutaminolysis and fatty acid synthesis in cancer cells under acidosis are increased, while TCA cycle and glycolysis are decreased. Under lactic acidosis, the pentose phosphate pathway and acetate release are increased in MDA-MB-231 cells. The current results uncovered the different metabolic responses of breast cancer cells to acidosis and lactic acidosis, demonstrating the power of combined untargeted and stable isotope assisted metabolomics in comprehensive metabolomic analysis.
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