ABSTRACTEnhancing green innovation is the key to realizing high-quality development and the “dual-carbon” goal. This paper takes the data from Chinese cities from 2000 to 2018 as a sample to test the ...impact and mechanism of local governments’ competition for the environment on urban green innovation. The study found that local government competition for the environment can effectively promote urban green innovation, and the spatial spillover effect is significant and can lead neighboring cities to improve the level of green innovation jointly. The results of the mechanism test indicate that local government competition promotes green innovation through two channels: influencing fiscal expenditure bias and the establishment of development zones. Further analysis shows that the impact of government competition on green innovation has apparent spatial heterogeneity, while the double-threshold effect results in an “N”-shaped relationship between local government competition and urban green innovation.
Electrochemical water splitting is considered as a promising approach to produce clean and sustainable hydrogen fuel. As a new class of nanomaterials with high ratio of surface atoms and tunable ...composition and electronic structure, metal clusters are promising candidates as catalysts. Here, a new strategy is demonstrated to synthesize active and stable Pt‐based electrocatalysts for hydrogen evolution by confining Pt clusters in hollow mesoporous carbon spheres (Pt5/HMCS). Such a structure would effectively stabilize the Pt clusters during the ligand removal process, leading to remarkable electrocatalytic performance for hydrogen production in both acidic and alkaline solutions. Particularly, the optimal Pt5/HMCS electrocatalyst exhibits 12 times the mass activity of Pt in commercial Pt/C catalyst with similar Pt loading. This study exemplifies a simple yet effective approach to improve the cost effectiveness of precious‐metal‐based catalysts with stabilized metal clusters.
Sub‐nanometer Pt clusters confined in mesoporous carbon nanochannels are developed as a novel electrocatalyst for the hydrogen evolution reaction. The unique structure effectively stabilizes the Pt clusters during the ligand removal and catalytic process, leading to remarkable electrocatalytic performance for hydrogen production in both acidic and alkaline solutions.
A Au55 nanocluster with the composition of Au55(p‐MBT)24(Ph3P)6(SbF6)3 (p‐MBT=4‐methylbenzenethiolate) is synthesized via direct reduction of gold‐phosphine and gold‐thiolate precursors. ...Single‐crystal X‐ray diffraction reveals that this Au55 nanocluster features a face‐centered cubic (fcc) Au55 kernel, different from the well‐known two‐shell cuboctahedral arrangement in Au55(Ph3P)12Cl6. The Au55 cluster shows a wide optical absorption band with optical energy gap (Eg=1.28 eV). It is found that the exclusion of chloride is crucial for the formation of the title cluster, otherwise rod‐like Au25(SR)5(PPh3)10Cl22+ is obtained. The strategy to run synthetic reaction in the absence of halide leads to new members of phosphine/thiolate co‐protected metal nanoclusters. The Au55 nanocluster exhibits high catalytic activity and selectivity for electrochemical reduction of CO2 to CO; the Faradaic efficiency (FE) reaches 94.1 % at −0.6 V vs. reversible hydrogen electrode (RHE).
The gold nanocluster Au55(p‐MBT)24(Ph3P)6(SbF6)3 (p‐MBT=4‐methylbenzenethiolate) features a face‐centered cubic Au55 kernel. This cluster exhibits high catalytic activity and selectivity for electrochemical reduction of CO2 to CO, and the Faradaic efficiency (FE) reaches 94.1 % at −0.6 V. The exclusion of chloride is an effective strategy to generate new members of ligand‐protected metal nanoclusters.
Biomaterials currently used in cardiac tissue engineering have certain limitations, such as lack of electrical conductivity and appropriate mechanical properties, which are two parameters playing a ...key role in regulating cardiac cell behavior. Here, the myocardial tissue constructs are engineered based on reduced graphene oxide (rGO)‐incorporated gelatin methacryloyl (GelMA) hybrid hydrogels. The incorporation of rGO into the GelMA matrix significantly enhances the electrical conductivity and mechanical properties of the material. Moreover, cells cultured on composite rGO‐GelMA scaffolds exhibit better biological activities such as cell viability, proliferation, and maturation compared to ones cultured on GelMA hydrogels. Cardiomyocytes show stronger contractility and faster spontaneous beating rate on rGO‐GelMA hydrogel sheets compared to those on pristine GelMA hydrogels, as well as GO‐GelMA hydrogel sheets with similar mechanical property and particle concentration. Our strategy of integrating rGO within a biocompatible hydrogel is expected to be broadly applicable for future biomaterial designs to improve tissue engineering outcomes. The engineered cardiac tissue constructs using rGO incorporated hybrid hydrogels can potentially provide high‐fidelity tissue models for drug studies and the investigations of cardiac tissue development and/or disease processes in vitro.
Incorporating reduced graphene oxide (rGO) inside GelMA hydrogels enhanced their electrical conductivity and mechanical properties. Cardiomyocytes showed faster spontaneous beating rate and higher expression of cardiac markers on rGO‐GelMA hydrogels compared to those on pristine GelMA and GO‐GelMA hydrogel. rGO reinforcement combined with an extracellular matrix‐derived biopolymer offers a promising material for fabrication of tissue constructs for cardiac tissue engineering.
Covalent organic frameworks (COFs) represent a new type of crystalline porous materials that are covalently assembled from organic building blocks. Construction of functional COFs is, however, a ...difficult task because it has to meet simultaneously the requirements for crystallinity and functionality. We report herein a facile strategy for the direct construction of chiral-functionalized COFs from chiral building blocks. The key design is to use the rigid scaffold 4,4′-(1H-benzodimidazole-4,7-diyl)dianiline (2) for attaching a variety of chiral moieties. As a first example, the chiral pyrrolidine-embedded building block (S)-4,4′-(2-(pyrrolidin-2-yl)-1H-benzodimidazole-4,7-diyl)dianiline (3) was accordingly synthesized and applied for the successful construction of two chiral COFs, LZU-72 and LZU-76. Our experimental results further showed that these chiral COFs are structurally robust and highly active as heterogeneous organocatalysts.
For the first time total structure determination of homoleptic alkynyl‐protected gold nanoclusters is reported. The nanoclusters are synthesized by direct reduction of PhC≡CAu, to give Au44(PhC≡C)28 ...and Au36(PhC≡C)24. The Au44 and Au36 nanoclusters have fcc‐type Au36 and Au28 kernels, respectively, as well as surrounding PhC≡C‐Au‐C2(Ph)Au‐C≡CPh dimeric “staples” and simple PhC≡C bridges. The structures of Au44(PhC≡C)28 and Au36(PhC≡C)24 are similar to Au44(SR)28 and Au36(SR)24, but the UV/Vis spectra are different. The protecting ligands influence the electronic structures of nanoclusters significantly. The synthesis of these two alkynyl‐protected gold nanoclusters indicates that a series of gold nanoclusters in the general formula Aux(RC≡C)y as counterparts to Aux(SR)y can be expected.
All alkynyl: The structure determinations of Au44(PhC≡C)28 and Au36(PhC≡C)24 are the first of homoleptic alkynyl‐protected gold nanoclusters. The structures are similar to those of Au44(SR)28 and Au36(SR)24, respectively, but the UV/Vis spectra are distinctly different.
Total structure determination of a ligand‐protected gold nanocluster, Au144, has been successfully carried out. The composition of title nanocluster is Au144(C≡CAr)60 (1; Ar=2‐FC6H4‐). The cluster 1 ...exhibits a quasi‐spherical Russian doll‐like architecture, comprising a Au54 two‐shelled Mackay icosahedron (Au12@Au42), which is further enclosed by a Au60 anti‐Mackay icosahedral shell. The Au114 kernel is enwrapped by thirty linear ArC≡C‐Au‐C≡CAr staple motifs. The absorption spectrum of 1 shows two bands at 560 and 620 nm. This spectrum is distinctly different from that of thiolated Au144, which was predicted to have an almost identical metal kernel and very similar ligands arrangement in 1. These facts indicate the molecule‐like behavior of 1 and significant involvement of ligands in the electronic structure of 1. The cluster 1 is hitherto the largest coinage metal nanocluster with atomically precise molecular structure in the alkynyl family. The work not only addresses the concern of structural information of Au144, which had been long‐pursued, but also provides an interesting example showing ligand effects on the optical properties of ligand protected metal nanoclusters.
Layer by layer: Total structure determination of a ligand‐protected gold nanocluster Au144, hitherto the largest coinage metal nanocluster in the alkynyl family, has been successfully conducted. This work not only addresses the concern of structural information of Au144, which had been long‐pursued, but also provides an interesting example of ligand effects on the optical properties of ligand‐protected metal nanoclusters.
To create life‐like movements, living muscle actuator technologies have borrowed inspiration from biomimetic concepts in developing bioinspired robots. Here, the development of a bioinspired soft ...robotics system, with integrated self‐actuating cardiac muscles on a hierarchically structured scaffold with flexible gold microelectrodes is reported. Inspired by the movement of living organisms, a batoid‐fish‐shaped substrate is designed and reported, which is composed of two micropatterned hydrogel layers. The first layer is a poly(ethylene glycol) hydrogel substrate, which provides a mechanically stable structure for the robot, followed by a layer of gelatin methacryloyl embedded with carbon nanotubes, which serves as a cell culture substrate, to create the actuation component for the soft body robot. In addition, flexible Au microelectrodes are embedded into the biomimetic scaffold, which not only enhance the mechanical integrity of the device, but also increase its electrical conductivity. After culturing and maturation of cardiomyocytes on the biomimetic scaffold, they show excellent myofiber organization and provide self‐actuating motions aligned with the direction of the contractile force of the cells. The Au microelectrodes placed below the cell layer further provide localized electrical stimulation and control of the beating behavior of the bioinspired soft robot.
A bioinspired robot is designed and fabricated by mimicking the biomechanical model of a batoid fish, which is composed of two micropatterned hydrogel layers and flexible microelectrodes to induce driving the contractions of the soft robot by electrical stimulation. The bioinspired robot shows actuation aligned with the direction of the contractile force of the cells.
The chirality of a gold nanocluster can be generated from either an intrinsically chiral inorganic core or an achiral inorganic core in a chiral environment. The first structural determination of a ...gold nanocluster containing an intrinsic chiral inorganic core is reported. The chiral gold nanocluster Au20(PP3)4Cl4 (PP3=tris(2‐(diphenylphosphino)ethyl)phosphine) has been prepared by the reduction of a gold(I)–tetraphosphine precursor in dichloromethane solution. Single‐crystal structural determination reveals that the cluster molecular structure has C3 symmetry. It consists of a Au20 core consolidated by four peripheral tetraphosphines. The Au20 core can be viewed as the combination of an icosahedral Au13 and a helical Y‐shaped Au7 motif. The identity of this Au20 cluster is confirmed by ESI‐MS. The chelation of multidentate phosphines enhances the stability of this Au20 cluster.
Gold with a twist: A chiral Au20 nanocluster has been prepared by the reduction of a gold(I)–tetraphosphine complex. The C3 Au20 core can be viewed as the combination of an icosahedral Au13 (see picture, orange) and a helical Y‐shaped Au7 motif (green). This is the first structural determination of a gold nanocluster containing an intrinsic chiral inorganic core.
The launch of the selection process for National Development Zones(NDZs) marked a fundamental change in the construction of development zones, making it an essential position for local authorities to ...implement high-quality development. Based on the data of prefecture-level cities in China from 2000 to 2018, this paper examines the impact and mechanism of selecting NDZs on urban green innovation through a double-difference spatial durbin model using the selection of NDZs as a “quasi-natural experiment”. The study finds that the selection of NDZs can promote green innovation in cities and has a significant window-radiating effect. The heterogeneity test results show that the implementation of the selection policy for development zones in non-old industrial cities, large and medium-sized cities, cities with easy access to transportation, and cities with high market orientation are more likely to promote urban green innovation. At the same time, the higher the level of government governance and the better the level of economic development of the development zones, the more it helps to realize the effects of the selection policy. The results of the mechanism test show that the selection of NDZs has a positive impact on urban green innovation through environmental regulation effects, resource allocation effects, and policy amplification effects.
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