Abstract
Hydrogen energy is critical for achieving carbon neutrality. Heterostructured materials with single metal-atom dispersion are desirable for hydrogen production. However, it remains a great ...challenge to achieve large-scale fabrication of single atom-anchored heterostructured catalysts with high stability, low cost, and convenience. Here, we report single iron (Fe) atom-dispersed heterostructured Mo-based nanosheets developed from a mineral hydrogel. These rationally designed nanosheets exhibit excellent hydrogen evolution reaction (HER) activity and reliability in alkaline condition, manifesting an overpotential of 38.5 mV at 10 mA cm
−2
, and superior stability without performance deterioration over 600 h at current density up to 200 mA cm
−2
, superior to most previously reported non-noble-metal electrocatalysts. The experimental and density functional theory results reveal that the O-coordinated single Fe atom-dispersed heterostructures greatly facilitated H
2
O adsorption and enabled effective adsorbed hydrogen (H*) adsorption/desorption. The green, scalable production of single-atom-dispersed heterostructured HER electrocatalysts reported here is of great significance in promoting their large-scale implementation.
The low energy efficiency and limited cycling life of rechargeable Zn–air batteries (ZABs) arising from the sluggish oxygen reduction/evolution reactions (ORR/OERs) severely hinder their commercial ...deployment. Herein, a zeolitic imidazolate framework (ZIF)‐derived strategy associated with subsequent thermal fixing treatment is proposed to fabricate dual‐atom CoFe─N─C nanorods (Co1Fe1─N─C NRs) containing atomically dispersed bimetallic Co/Fe sites, which can promote the energy efficiency and cyclability of ZABs simultaneously by introducing the low‐potential oxidation redox reactions. Compared to the mono‐metallic nanorods, Co1Fe1─N─C NRs exhibit remarkable ORR performance including a positive half‐wave potential of 0.933 V versus reversible hydrogen electrode (RHE) in alkaline electrolyte. Surprisingly, after introducing the potassium iodide (KI) additive, the oxidation overpotential of Co1Fe1─N─C NRs to reach 10 mA cm−2 can be significantly reduced by 395 mV compared to the conventional destructive OER. Theoretical calculations show that the markedly decreased overpotential of iodide oxidation can be ascribed to the synergistic effects of neighboring Co─Fe diatomic sites as the unique adsorption sites. Overall, aqueous ZABs assembled with Co1Fe1─N─C NRs and KI as the air–cathode catalyst and electrolyte additive, respectively, can deliver a low charging voltage of 1.76 V and ultralong cycling stability of over 230 h with a high energy efficiency of ≈68%.
A zeolitic imidazolate framework (ZIF)derived strategy associated with subsequent thermal fixing treatment is proposed to fabricate dual‐atom CoFe─N─C nanorods containing atomically dispersed bimetallic Co/Fe sites, which can be used as bifunctional air–cathode catalysts to boost the energy efficiency and cyclability of Zn–air batteries simultaneously by introducing low‐potential oxidation redox reactions.
Layered stacking and highly porous N, P co-doped Mo
C/C nanosheets are prepared from a stable Mo-enhanced hydrogel. The hydrogel is formed through the ultrafast cross-linking of phosphomolybdic acid ...and chitosan. During the reduction of the composite hydrogel framework under inert gas protection, highly porous N and P co-doped carbon nanosheets are produced with the in situ formation of ultrafine Mo
C nanoparticles highly distributed throughout the nanosheets which are entangled via a hierarchical lamellar infrastructure. This unique architecture of the N, P co-doped Mo
C/C nanosheets tremendously promote the electrochemical activity and operate stability with high specific capacity and extremely stable cycling. In particular, this versatile synthetic strategy can also be extended to other polyoxometalate (such as phosphotungstic acid) to provide greater opportunities for the controlled fabrication of novel hierarchical nanostructures for next-generation high performance energy storage applications.
Developing noble‐metal‐free based electrocatalysts with high activity, good stability, and low cost is critical for large‐scale hydrogen production via water splitting. In this work, hollow FeP ...nanoparticles densely encapsulated in carbon nanosheet frameworks (donated as hollow FeP/C nanosheets), in situ converted from Fe‐glycolate precursor nanosheets through carbonization and subsequent phosphorization, are designed and synthesized as an advanced electrocatalyst for the hydrogen evolution reaction. FeP hollow nanoparticles are transformed from intermediate Fe3O4 nanoparticles through the nanoscale Kirkendall effect. The two‐dimensional architecture, densely embedding FeP hollow nanoparticles, provides abundant accessible active sites and short electron and ion pathways. The in situ generated carbon nanosheet frameworks can not only offer a conductive network but also protect the active FeP from oxidation. As a result, hollow FeP/C nanosheets exhibit excellent electrocatalytic performance for the hydrogen evolution reaction in 0.5 m H2SO4 with a quite low overpotential of 51.1 mV at 10 mA cm−2, small Tafel slope of 41.7 mV dec−1, and remarkable long‐term stability. The study highlights the in situ synthesis of two‐dimensional metal phosphide/C nanocomposites with highly porous features for advanced energy storage and conversion.
FeP hollow nanoparticles densely encapsulated in carbon nanosheet frameworks are fabricated via a facile precursor‐directed nanoscale Kirkendall effect. Thanks to the structural merits of porous nanosheets and carbon protecting, the product exhibits excellent electrochemical performance for the hydrogen evolution reaction with very low overpotential, fast kinetics as well as remarkable stability.
The distribution and deposition of fat tissue in different parts of the body are the key factors affecting the carcass quality and meat flavour of chickens. Intramuscular fat (IMF) content is an ...important factor associated with meat quality, while abdominal fat (AbF) is regarded as one of the main factors affecting poultry slaughter efficiency. To investigate the differentially expressed genes (DEGs) and molecular regulatory mechanisms related to adipogenic differentiation between IMF- and AbF-derived preadipocytes, we analysed the mRNA expression profiles in preadipocytes (0d, Pre-) and adipocytes (10d, Ad-) from IMF and AbF of Gushi chickens.
AbF-derived preadipocytes exhibited a higher adipogenic differentiation ability (96.4% + 0.6) than IMF-derived preadipocytes (86.0% + 0.4) (p < 0.01). By Ribo-Zero RNA sequencing, we obtained 4403 (2055 upregulated and 2348 downregulated) and 4693 (2797 upregulated and 1896 downregulated) DEGs between preadipocytes and adipocytes in the IMF and Ad groups, respectively. For IMF-derived preadipocyte differentiation, pathways related to the PPAR signalling pathway, ECM-receptor interaction and focal adhesion pathway were significantly enriched. For AbF-derived preadipocyte differentiation, the steroid biosynthesis pathways, calcium signaling pathway and ECM-receptor interaction pathway were significantly enriched. A large number of DEGs related to lipid metabolism, fatty acid metabolism and preadipocyte differentiation, such as PPARG, ACSBG2, FABP4, FASN, APOA1 and INSIG1, were identified in our study.
This study revealed large transcriptomic differences between IMF- and AbF-derived preadipocyte differentiation. A large number of DEGs and transcription factors that were closely related to fatty acid metabolism, lipid metabolism and preadipocyte differentiation were identified in the present study. Additionally, the microenvironment of IMF- and AbF-derived preadipocyte may play a significant role in adipogenic differentiation. This study provides valuable evidence to understand the molecular mechanisms underlying adipogenesis and fat deposition in chickens.
Implementing green development is important to realizing a harmonious relationship between humans and nature, and has attracted the attention of governments all over the world. This paper uses the ...PMC (Policy Modeling Consistency) model to make a quantitative evaluation of 21 representative green development policies issued by the Chinese government. The research finds: firstly, the overall evaluation grade of green development is good and the average PMC index of China's 21 green development policies is 6.59. Second, the evaluation of 21 green development policies can be divided into four different grades. Most grades of the 21 policies are excellent and good; the values of five first-level indicators about policy nature, policy function, content evaluation, social welfare, and policy object are high, which indicates that the 21 green development policies in this paper are relatively comprehensive and complete. Third, most green development policies are feasible. In twenty-one green development policies, there are: one perfect-grade policy, eight excellent-grade policies, ten good-grade policies, and two bad-grade policies. Fourthly, this paper analyzes the advantages and disadvantages of policies in different evaluation grades by drawing four PMC surface graphs. Finally, based on the research findings, this paper puts forward suggestions to optimize the green development policy-making of China.
Evaluating the level of green development is of great significance to better implement the concept of green development. By constructing an evaluation index system for green development, this paper ...comprehensively uses the entropy weight Technique for Order Preference by Similarity to an Ideal Solution (TOPSIS) method and coefficient of variation method to evaluate the green development level of 30 provinces in China from 2010 to 2019 and analyzes the regional differences of green development in China. The research findings are as follows: First, the level of green development in China is low but shows a slow rise trend, from 2010 to 2019; China's green development level rises from 0.274 to 0.317, an increase of 15.7%. Secondly, regional differences of green development in China are obvious, with the level ranking from high to low as eastern, western, and central regions. Third, regional differences in China's green development first widen and then narrow, with the variation coefficient of green development in 30 provinces and eastern, central, and western regions of China showing an inverted U-shaped trend of first increasing and then decreasing. Fourth, the regional difference of green development in eastern China is largest, followed by western China, and the smallest is central China. Finally, based on research findings, relevant policy recommendations are put forward.
Layered stacking and highly porous N, P co‐doped Mo2C/C nanosheets are prepared from a stable Mo‐enhanced hydrogel. The hydrogel is formed through the ultrafast cross‐linking of phosphomolybdic acid ...and chitosan. During the reduction of the composite hydrogel framework under inert gas protection, highly porous N and P co‐doped carbon nanosheets are produced with the in situ formation of ultrafine Mo2C nanoparticles highly distributed throughout the nanosheets which are entangled via a hierarchical lamellar infrastructure. This unique architecture of the N, P co‐doped Mo2C/C nanosheets tremendously promote the electrochemical activity and operate stability with high specific capacity and extremely stable cycling. In particular, this versatile synthetic strategy can also be extended to other polyoxometalate (such as phosphotungstic acid) to provide greater opportunities for the controlled fabrication of novel hierarchical nanostructures for next‐generation high performance energy storage applications.
A method for fabricating lamellarly stacking porous N, P co‐doped transition metal carbide/C nanosheets is reported. The nanosheets are derived from a hydrogel which is formed through the ultrafast cross‐linking of polyoxometallate and chitosan, and are highly porous with N and P co‐doping.
Fabrication of single-crystalline metal-organic framework (MOF) hollow nanostructures with two-dimensional (2D) morphologies is a challenging task. Herein, twin-like MOF nanobricks, a quasi-hollow 2D ...architecture, with multi-metal nodes and replaceable organic ligands, are uniformly and firmly grown on conductive Ni foam through a generic one-pot approach. The formation process of twin-like MOF nanobricks mainly includes selective epitaxial growth of Fe-rich MOF layer and simultaneously dissolution of the pre-formed Ni-rich metal-organic frameworks (MOFs), all of which can be ascribed to a special self-templated mechanism. The fantastic structural merits of twin-like MOF nanobrick arrays, featuring highly exposed active sites, remarkable electrical conductivity, and hierarchical porosities, enable this material for efficient electrocatalysis. Using bimetallic NiFe-MOFs grown on Ni foam as an example, the resultant twin-like nanobrick arrays can be directly utilized as three-dimensional (3D) integrated electrode for high-performance water oxidation in 1 M KOH with a low overpotential, fast reaction kinetics (28.5 mV·dec
−1
), and superb stability. Interestingly, the unstable NiFe-MOFs were served as an oxygen evolution reaction (OER) pre-catalyst and the single-crystalline NiFe-MOF precursor can be
in-situ
topochemically regulated into porous and low-crystalline NiFeO
x
nanosheets during the OER process. This work extends the hollowing strategy to fabricate hollow MOFs with 2D architectures and highlights their direct utilization for advanced electrocatalysis.
Single‐atom Fe‐N‐C (denoted as Fe1‐N‐C) catalysts exhibit inadequate bifunctional activities to conquer the sluggish oxygen reduction and evolution reaction (ORR/OER), hindering their practical ...applications in rechargeable Zn‐air batteries (ZABs). Here, by employing Fe1‐N‐C hollow nanorods as ORR‐active support, OER‐active NiFe‐layered double hydroxide (NiFe‐LDH) nanodots are evenly decorated through a spatially confined process to form NiFe‐LDH/Fe1‐N‐C heterostructure hollow nanorods with abundant accessible catalytic sites. The NiFe‐LDH/Fe1‐N‐C heterostructure not only enhances the ORR activity of pristine Fe1‐N‐C but also realizes efficient bifunctional ORR/OER activity in one monolithic catalyst. Theoretical calculations reveal that introducing NiFe‐LDH nanodots results in donation of electrons to the Fe1‐N‐C matrix and thus lowers the Fe‐d band center of the Fe‐N4 sites, dramatically narrowing the energy barriers of the ORR rate‐limiting steps. As a result, NiFe‐LDH/Fe1‐N‐C nanorods deliver remarkable ORR activity with a half‐wave potential of 0.90 V versus reversible hydrogen electrode, surpassing bare Fe1‐N‐C and commercial Pt/C. Impressively, the integrated NiFe‐LDH/Fe1‐N‐C catalysts show outstanding bifunctional performance with a small overpotential gap of only 0.65 V. The liquid‐state ZABs with NiFe‐LDH/Fe1‐N‐C as an air‐cathode catalyst deliver a peak power density of 205 mW cm−2 and long‐term cycling stability of up to 400 h.
Oxygen evolution reaction (OER)‐active NiFe‐layered double hydroxide (LDH) nanodots are evenly decorated on the oxygen reduction reaction (ORR)‐active Fe1‐N‐C hollow nanorods to realize bifunctional ORR/OER activity in one monolithic catalyst with a small overpotential gap of only 0.65 V. NiFe‐LDH regulates the electronic structures of Fe1‐N‐C by transferring electrons to the Fe‐N4‐active sites and thus significantly reduces the energy barrier of the rate‐determining step during the ORR.
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