Taking AuCu3-type sublattice system as an example, three discoveries have been presented: First, the third barrier hindering the progress in metal materials science is that researchers have got used to recognizing exp...Taking AuCu3-type sublattice system as an example, three discoveries have been presented: First, the third barrier hindering the progress in metal materials science is that researchers have got used to recognizing experimental phenomena of alloy phase transitions during extremely slow variation in temperature by equilibrium thinking mode and then taking erroneous knowledge of experimental phenomena as selected information for establishing Gibbs energy function and so-called equilibrium phase diagram. Second, the equilibrium holographic network phase diagrams of AuCu3-type sublattice system may be used to describe systematic correlativity of the composition?temperature-dependent alloy gene arranging structures and complete thermodynamic properties, and to be a standard for studying experimental subequilibrium order-disorder transition. Third, the equilibrium transition of each alloy is a homogeneous single-phase rather than a heterogeneous two-phase, and there exists a single-phase boundary curve without two-phase region of the ordered and disordered phases; the composition and temperature of the top point on the phase-boundary curve are far away from the ones of the critical point of the AuCu3 compound.展开更多
Rational design and construction of chiral-achiral hybrid structures are of great importance to realize the multifunctional complex chiral structures toward emerging technological applications. However, significant ch...Rational design and construction of chiral-achiral hybrid structures are of great importance to realize the multifunctional complex chiral structures toward emerging technological applications. However, significant challenges remain due to the lack of fine control over the heterostructure. Here, we have developed a general bottom-up synthetic strategy for the site-selective growth of Cu nanodomains on intrinsically chiral Au nanocrystals. Chiral AuCu heterostructures with three distinct architectures were achieved by controlling the overgrowth of Cu nanodomains in a site-specific manner. The geometry-dependent plasmonic chirality of the heterostructures was demonstrated experimentally by circular dichroism spectroscopy and theoretically through finite-difference time-domain simulations. The site-specific geometric control of chiral AuCu heterostructures was also extended to employ anisotropic chiral Au nanoplates and nanorods as the building blocks. By virtue of the galvanic replacement reactions between metal ions and Cu atoms, chiral heterostructures with increasing architectural complexity and compositional diversity can be further achieved. The current work not only opens up a promising strategy to synthesize complex chiral hybrid nanostructures but also provides an important knowledge framework that guides the rational design of multifunctional chiral hybrid nanostructures toward chiroptical applications.展开更多
The direct electrochemical conversion of CO_(2) to syngas with controllable composition remains challenging. In this work, driven by concentration gradient, a simple air-heating aided strategy has been developed to ad...The direct electrochemical conversion of CO_(2) to syngas with controllable composition remains challenging. In this work, driven by concentration gradient, a simple air-heating aided strategy has been developed to adjust surface composition of the self-supporting nanoporous AuCu_(3) alloy. According to Fick First Law, the interior Cu atoms of the AuCu_(3) alloy with Au-rich surface gradually segregated outwards during heating, realizing Cu-rich surface eventually. Correspondingly, the competing electrocatalytic CO_(2) reduction (ECR) to CO and hydrogen evolution reactions (HER) were tactfully balanced on these alloy surfaces, thus achieving proportion-tunable syngas (CO/H2). Density functional theory (DFT) calculations on the Gibbs free energy change of the COOH* and H* (ΔGCOOH*, ΔGH*) on the alloy surfaces were conducted, which are generally considered as the selectivity descriptors for CO and H2 products, respectively. It shows ΔGCOOH* gradually increases in contrast to the decreased ΔGH* with more Cu on the surface, suggesting H2 is more favored over Cu sites, which is consistent with the declining CO/H2 ratio observed in the experiments. This study reveals that the surface composition controls ECR activity of nanoporous AuCu_(3) alloy, providing an alternative way to the syngas production with desirable proportion.展开更多
Single-helical or double-helical structures are common in living organisms.Helical assembly has been found in the artificial nanoparticles,but how they do so remains poorly understood.Here,we exploit atomically precis...Single-helical or double-helical structures are common in living organisms.Helical assembly has been found in the artificial nanoparticles,but how they do so remains poorly understood.Here,we exploit atomically precise Au_(6)Cu_(6)bimetallic nanoparticles(or called nanoclusters)as building blocks to construct a single-helical Au_(12)Cu_(12)superstructure in an operative path,thereby providing access to currently elusive mechanistic pathways.We propose that the thermodynamically viable linearto-bent process at a couple of Au_(6)Cu_(6)nanoclusters imparted by the organic ligands seems to be critical for the helical-nanostructured arrangement of Au_(12)Cu_(12).This study could help to offer a new design rule for the exquisitely helical structure assembled from the artificial nanoparticles.展开更多
Au-based catalysts have been reported to be active in the cyclohexane oxidation to K-A oil, but they showed some limitiations in terms of productivity, selectivity and required reaction conditions. The possibility to ...Au-based catalysts have been reported to be active in the cyclohexane oxidation to K-A oil, but they showed some limitiations in terms of productivity, selectivity and required reaction conditions. The possibility to overcome some of these limits has been explored coupling Au with Cu, which can be suitable for undergoing the electron-switch in the initial step of the cyclohexane oxidation. Hence, a bimetallic 2 wt% Au Cu/Al_(2)O_(3) catalyst was tested in the oxidation of cyclohexane, working at mild conditions of 120 ℃ and 4 bar of O_(2). The combination of the catalyst with a very small amount of benzaldehyde used as cheaper and non-toxic radical initiator allowed to obtain a very high productivity of cyclohexanol and cyclohexanone(45 mmol*m L/mgmet*h) with a selectivity of 94%. Moreover, comparing the catalysed reaction with the non-catalysed one, the role of the catalyst has been disclosed.展开更多
基金Project(51071181)supported by the National Natural Science Foundation of ChinaProject(2013FJ4043)supported by the Natural Science Foundation of Hunan Province,China
文摘Taking AuCu3-type sublattice system as an example, three discoveries have been presented: First, the third barrier hindering the progress in metal materials science is that researchers have got used to recognizing experimental phenomena of alloy phase transitions during extremely slow variation in temperature by equilibrium thinking mode and then taking erroneous knowledge of experimental phenomena as selected information for establishing Gibbs energy function and so-called equilibrium phase diagram. Second, the equilibrium holographic network phase diagrams of AuCu3-type sublattice system may be used to describe systematic correlativity of the composition?temperature-dependent alloy gene arranging structures and complete thermodynamic properties, and to be a standard for studying experimental subequilibrium order-disorder transition. Third, the equilibrium transition of each alloy is a homogeneous single-phase rather than a heterogeneous two-phase, and there exists a single-phase boundary curve without two-phase region of the ordered and disordered phases; the composition and temperature of the top point on the phase-boundary curve are far away from the ones of the critical point of the AuCu3 compound.
基金supported by the National Natural Science Foundation of China (22174104 to Q.Z.)the support of the Hubei Provincial Natural Science Foundation of China (2022CFB627)the Fundamental Research Funds for the Central Universities (20422022kf1039)。
文摘Rational design and construction of chiral-achiral hybrid structures are of great importance to realize the multifunctional complex chiral structures toward emerging technological applications. However, significant challenges remain due to the lack of fine control over the heterostructure. Here, we have developed a general bottom-up synthetic strategy for the site-selective growth of Cu nanodomains on intrinsically chiral Au nanocrystals. Chiral AuCu heterostructures with three distinct architectures were achieved by controlling the overgrowth of Cu nanodomains in a site-specific manner. The geometry-dependent plasmonic chirality of the heterostructures was demonstrated experimentally by circular dichroism spectroscopy and theoretically through finite-difference time-domain simulations. The site-specific geometric control of chiral AuCu heterostructures was also extended to employ anisotropic chiral Au nanoplates and nanorods as the building blocks. By virtue of the galvanic replacement reactions between metal ions and Cu atoms, chiral heterostructures with increasing architectural complexity and compositional diversity can be further achieved. The current work not only opens up a promising strategy to synthesize complex chiral hybrid nanostructures but also provides an important knowledge framework that guides the rational design of multifunctional chiral hybrid nanostructures toward chiroptical applications.
基金This work was financially supported by the National Natural Science Foundation of China(No.21771137)the Training Project of Innovation Team of Colleges and Universities in Tianjin(No.TD13-5020)the Natural Science Foundation of Tianjin City of China(No.18JCJQJC47700).
文摘The direct electrochemical conversion of CO_(2) to syngas with controllable composition remains challenging. In this work, driven by concentration gradient, a simple air-heating aided strategy has been developed to adjust surface composition of the self-supporting nanoporous AuCu_(3) alloy. According to Fick First Law, the interior Cu atoms of the AuCu_(3) alloy with Au-rich surface gradually segregated outwards during heating, realizing Cu-rich surface eventually. Correspondingly, the competing electrocatalytic CO_(2) reduction (ECR) to CO and hydrogen evolution reactions (HER) were tactfully balanced on these alloy surfaces, thus achieving proportion-tunable syngas (CO/H2). Density functional theory (DFT) calculations on the Gibbs free energy change of the COOH* and H* (ΔGCOOH*, ΔGH*) on the alloy surfaces were conducted, which are generally considered as the selectivity descriptors for CO and H2 products, respectively. It shows ΔGCOOH* gradually increases in contrast to the decreased ΔGH* with more Cu on the surface, suggesting H2 is more favored over Cu sites, which is consistent with the declining CO/H2 ratio observed in the experiments. This study reveals that the surface composition controls ECR activity of nanoporous AuCu_(3) alloy, providing an alternative way to the syngas production with desirable proportion.
基金National Natural Science Foundation of China,Grant/Award Number:22101128the Fundamental Research Funds for the Central Universities+1 种基金Foshan Science and Technology Innovation Project,Grant/Award Number:2018IT100363Programs for high-level entrepreneurial and innovative talents introduction of Jiangsu Province。
文摘Single-helical or double-helical structures are common in living organisms.Helical assembly has been found in the artificial nanoparticles,but how they do so remains poorly understood.Here,we exploit atomically precise Au_(6)Cu_(6)bimetallic nanoparticles(or called nanoclusters)as building blocks to construct a single-helical Au_(12)Cu_(12)superstructure in an operative path,thereby providing access to currently elusive mechanistic pathways.We propose that the thermodynamically viable linearto-bent process at a couple of Au_(6)Cu_(6)nanoclusters imparted by the organic ligands seems to be critical for the helical-nanostructured arrangement of Au_(12)Cu_(12).This study could help to offer a new design rule for the exquisitely helical structure assembled from the artificial nanoparticles.
基金The Authors gratefully acknowledge the supportof bilateral project CNR-HAS(MTA)SAC.AD002.037.
文摘Au-based catalysts have been reported to be active in the cyclohexane oxidation to K-A oil, but they showed some limitiations in terms of productivity, selectivity and required reaction conditions. The possibility to overcome some of these limits has been explored coupling Au with Cu, which can be suitable for undergoing the electron-switch in the initial step of the cyclohexane oxidation. Hence, a bimetallic 2 wt% Au Cu/Al_(2)O_(3) catalyst was tested in the oxidation of cyclohexane, working at mild conditions of 120 ℃ and 4 bar of O_(2). The combination of the catalyst with a very small amount of benzaldehyde used as cheaper and non-toxic radical initiator allowed to obtain a very high productivity of cyclohexanol and cyclohexanone(45 mmol*m L/mgmet*h) with a selectivity of 94%. Moreover, comparing the catalysed reaction with the non-catalysed one, the role of the catalyst has been disclosed.
