A facile mixed complex synthesis method for perovskite oxides toward electrocatalytic oxygen reduction.

The perovskite-type La(0.5+x)Sr(0.5-x)FeO3-δ (x = 0.00, 0.10, 0.20) oxides for the electrocatalytic oxygen reduction reaction (ORR) were synthesized by a facile reaction-EDTA/citric acid mixed complex sol-gel method. The cubic single-phase perovskite structure of the as-prepared oxides is demonstrated using powder X-ray diffraction (XRD). Scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM-EDX), transmission electron microscopy/selected area electron diffraction (TEM-SAED), and X-ray photoelectron spectroscopy (XPS) characterizations were also conducted for the perovskite-type La(0.5+x)Sr(0.5-x)FeO3-δ (x = 0.00, 0.10, 0.20) oxides. Furthermore, the electrochemical ORR properties of the as-prepared oxides in alkaline media were studied, with the oxides exhibiting good electrocatalytic ORR performance.

Quinary RuRhPdPtAu high-entropy alloy as an efficient electrocatalyst for the hydrogen evolution reaction.

Quinary RuRhPdPtAu high-entropy alloy nanoparticles (HEA-NPs) were prepared for the first time from a deep eutectic solvent by an electrochemical method. Owing to the benefits of high entropy and abundant surface active sites, the RuRhPdPtAu HEA-NPs exhibit outstanding electrocatalytic performance for the hydrogen evolution reaction.

Coupled patterns of natural and anthropogenic resources in typical ecosystems in coastal areas of China.

The coastal area of Yancheng, China, is one of the hotspots for ecological research. Under the coupling of human and natural ecosystems, the region has gradually evolved into a coexistence of aquatic, agricultural and mudflat ecosystems. What are the patterns of natural and artificial resource inputs and patterns of change in ecosystems? How can ecological flows be analyzed at a uniform scale? Here, we selected six typical local ecosystems, namely, rice‒wheat for enterprises (RWE), rice‒wheat for smallholder households (RWS), chrysanthemum‒wheat (CW), fish polyculture (FP), juvenile crab farming (JF) and clam polyculture (CP), and analyzed their energy flow flux and sustainability based on emergy theory. The results showed that anthropogenic resource inputs were higher than natural resource inputs in all ecosystems, and the inputs of aquatic ecosystems were greater than those of agroecosystems. The greatest total input was 2.0 E+17 seJ/ha/yr for FP, and the lowest was 1.9 E+16 seJ/ha/yr for RWE. The proportions of renewable and artificial inputs for RWE, RWS, CW, FP, JF and CP were 32.8% vs. 96.1%, 40.3% vs. 96.5%, 34.7% vs. 97.0%, 32.6% vs. 99.4%, 55.1% vs. 98.5%, and 62.5% vs. 98.6%, respectively. The highest input to agroecosystems was nitrogen fertilizer, while in JF and CP, it was water, and feed (63.3%) accounted for the highest percentage of input in FP. JF and CP had lower environmental loads and higher sustainability than other ecosystems, but this still represents a high input compared to agroecosystems. Human-led resource coupling profoundly affects ecosystem sustainability, and various thresholds of energy use and ecological sustainability need to be studied in depth. Continuous exploration of methods and mechanisms for the maintenance and evolution of ecosystems with low total inputs and low inputs of non-renewable resources can contribute to high-quality sustainable development of an area or region.

Effects of Diets Containing Different Levels of Copper, Manganese, and Iodine on Rumen Fermentation, Blood Parameters, and Growth Performance of Yaks.

Copper, manganese, and iodine are part of a yak's required trace elements. However, knowledge about their dietary requirements is scarce. Therefore, an experiment was conducted to evaluate rumen fermentation, blood parameters, and growth performance and screen out the optimum levels of trace elements in yaks' diet. Here, 18 three-year-old castrated yaks were randomly divided into four groups, which fed with diets containing basal (CON: 4.40, 33.82, and 0 mg/kg) and low-level (LL: 10.00, 40.00, and 0.30 mg/kg), middle-level (ML: 15.00, 50.00, and 0.50 mg/kg), and high-level (HL: 20.00, 60.00, and 0.70 mg/kg) copper, manganese, and iodine for 30 days. With the increase in trace elements, yaks' daily weight gain (DWG), rumen pH, ammonia nitrogen, microbial protein (MCP), and volatile fatty acids levels and serum triglycerides and urea nitrogen levels showed firstly increasing and then decreasing trends and reached the highest values in ML, and serum ceruloplasmin and total superoxide dismutase (T-SOD) activities showed continuously increasing trends. Yaks' DWG, rumen MCP, butyrate, and valerate levels and serum triglycerides, urea nitrogen, ceruloplasmin, and T-SOD levels in ML were significantly higher than CON. Therefore, the recommended levels of copper, manganese, and iodine in growing yaks' diet are 15.00, 50.00, and 0.50 mg/kg (ML), respectively.

Near-infrared pumped, octave-tunable, on-chip mid-infrared Raman soliton source.

This article proposes and numerically demonstrates a widely tunable on-chip Raman soliton source based on a cascaded As2Se3 waveguide. The cascaded sub-waveguides (input and output) with varying widths act as nonlinear devices, while a tapered waveguide is arranged between them to achieve low-loss transmission. The input waveguide provides anomalous dispersion in the near-infrared band, thereby enabling the 1.96 µm source for Raman soliton self-frequency shift (SSFS) pumping. The output waveguide exhibits large anomalous dispersion and good mode confinement in the mid-infrared band thus supporting further SSFS process. A 2.29∼4.57 µm tunable Raman source is theoretically realized in this on-chip platform. This work presents a simple and easy-to-implement strategy to extend the tuning range of on-chip sources. Notably, to the best of our knowledge, this is the first demonstration of the cascading strategy for SSFS process in an on-chip platform. The proposed tunable source has great potential in integrated spectroscopy, gas sensing, and LiDAR applications.

Effects of sources and levels of dietary supplementary manganese on growing yak's in vitro rumen fermentation.

Introduction: Manganese (Mn) is an essential trace element for livestock, but little is known about the optimal Mn source and level for yak. Methods: To improve yak's feeding standards, a 48-h in vitro study was designed to examine the effect of supplementary Mn sources including Mn sulfate (MnSO4), Mn chloride (MnCl2), and Mn methionine (Met-Mn) at five Mn levels, namely 35 mg/kg, 40 mg/kg, 50 mg/kg, 60 mg/kg, and 70 mg/kg dry matter (includes Mn in substrates), on yak's rumen fermentation. Results: Results showed that Met-Mn groups showed higher acetate (p < 0.05), propionate, total volatile fatty acids (p < 0.05) levels, ammonia nitrogen concentration (p < 0.05), dry matter digestibility (DMD), and amylase activities (p < 0.05) compared to MnSO4 and MnCl2 groups. DMD (p < 0.05), amylase activities, and trypsin activities (p < 0.05) all increased firstly and then decreased with the increase of Mn level and reached high values at 40-50 mg/kg Mn levels. Cellulase activities showed high values (p < 0.05) at 50-70 mg/kg Mn levels. Microbial protein contents (p < 0.05) and lipase activities of Mn-Met groups were higher than those of MnSO4 and MnCl2 groups at 40-50 mg/kg Mn levels. Discussion: Therefore, Mn-met was the best Mn source, and 40 to 50 mg/kg was the best Mn level for rumen fermentation of yaks.

Shifts of active microbial community structure and functions in constructed wetlands responded to continuous decreasing temperature in winter.

Important functions of constructed wetland related to biogeochemical processes are mediated by soil microbes and low-temperature damage is the main limiting factor for microbes in winter. However, the response thresholds for active microbial community and enzyme activities to continuous decreases in temperature remain unclear. In this study, total 90 soil samples were collected every week over a 6-week period to track the dynamics of four enzymes involved in cycles of C, N, P and active bacterial community as field soil temperature decreased continuously from 6.62 °C to 0.55 °C. Enzyme activity changed suddenly when the temperature decreased to 4.83 °C, the nitrite reductase activity reduced by 36.2%, while alkaline phosphatase activity is increased by 396%. The cellulase and urease were only marginally influenced by cold stress. Decreased nitrite reductase activities corresponded with loss of nir-type denitrifiers important for nitrite reduction. For cold stress, N-related bacteria were sensitive species. Whereas increased alkaline phosphatase activity may be due to the fact that P-related bacteria were opportunistic species. Key functional taxa connected with degradation of cellulose promoted species coexistence and microbial network stability. The lower and upper temperature thresholds for community change were 4.85 °C and 6.30 °C, respectively. Collectively, these results revealed that microbial taxa involved in C, N and P cycling respond differently to continuous decreases in temperature and higher than 4.85 °C is an ideal environment to prevent loss of microbial diversity and functions in winter, providing a scientific reference for the targeted isolation and cultivation of key microbial taxa in rhizosphere soil and adjusting temperature range to improve the purification capacity of wetlands during low temperature periods.

Sb Nanoparticles Embedded in the N-Doped Carbon Fibers as Binder-Free Anode for Flexible Li-Ion Batteries.

Antimony (Sb) is considered a promising anode for Li-ion batteries (LIBs) because of its high theoretical specific capacity and safe Li-ion insertion potential; however, the LIBs suffer from dramatic volume variation. The volume expansion results in unstable electrode/electrolyte interphase and active material exfoliation during lithiation and delithiation processes. Designing flexible free-standing electrodes can effectively inhibit the exfoliation of the electrode materials from the current collector. However, the generally adopted methods for preparing flexible free-standing electrodes are complex and high cost. To address these issues, we report the synthesis of a unique Sb nanoparticle@N-doped porous carbon fiber structure as a free-standing electrode via an electrospinning method and surface passivation. Such a hierarchical structure possesses a robust framework with rich voids and a stable solid electrolyte interphase (SEI) film, which can well accommodate the mechanical strain and avoid electrode cracks and pulverization during lithiation/delithiation processes. When evaluated as an anode for LIBs, the as-prepared nanoarchitectures exhibited a high initial reversible capacity (675 mAh g-1) and good cyclability (480 mAh g-1 after 300 cycles at a current density of 400 mA g-1), along with a superior rate capability (420 mA h g-1 at 1 A g-1). This work could offer a simple, effective, and efficient approach to improve flexible and free-standing alloy-based anode materials for high performance Li-ion batteries.

A thiadiazolopyridine-functionalized Zr(iv)-based metal-organic framework for enhanced photocatalytic synthesis of tetrahydroquinolines under visible light.

Metal-organic framework (MOF) materials provide a versatile and promising platform for constructing heterogeneous photocatalysts with applications in organic transformations. One of the methods for enhancing MOFs' performance in photocatalysis relies on the elaborate design and functionalization of organic linkers. Here we reported a photoactive thiadiazolopyridine (TDP) moiety functionalized UiO-68 isoreticular Zr(iv)-based MOF (denoted as UiO-68-TDP) that was synthesized by the de novo approach of mixed dicarboxylate struts. Under blue LED irradiation and in an open air atmosphere, MOF UiO-68-TDP exhibited a largely higher photocatalytic activity for the synthesis of tetrahydroquinolines by oxidative annulation reaction between N,N-dimethylanilines and maleimides, in comparison to the benzothiadiazole decorated analogue MOF. Besides, UiO-68-TDP can be reused at least three times without significant loss of its photocatalytic activity and its framework was well maintained after these cycles. Furthermore, the related mechanism involving reactive oxygen species was properly proposed.

Carbon-Nanotube-Encapsulated-Sulfur Cathodes for Lithium-Sulfur Batteries: Integrated Computational Design and Experimental Validation.

To mitigate lithium-polysulfides (Li-PSs) shuttle in lithium-sulfur batteries (LiSBs), a unique carbon-nanotube-encapsulated-sulfur (S@CNT) cathode material with optimum open-ring sizes (ORSs) on the CNT walls were designed using an integrated computational approach followed by experimental validation. By calculating the transport barrier of Li+ ion through ORSs on the CNT walls and comparing the molecular size of solvents and Li-PSs with ORSs, optimum open-rings with 16-30 surrounding carbon atoms were predicted to selectively allow transportation of Li+ ion and evaporated sulfur while blocking both Li-PS and solvent molecules. A CNT oxidation process was proposed and simulated to generate these ORSs, and the results indicated that the optimum ORSs can be achieved by narrowly controlling the oxidation parameters. Subsequently, S@CNT cathodes were experimentally synthesized, confirming that optimum ORSs were generated in CNT oxidized at 475 K and exhibited more stable cycling behavior.

Fungi drive soil multifunctionality in the coastal salt marsh ecosystem.

Salt marshes are highly productive intertidal wetlands located in temperate climatic zones, in which marine-to-terrestrial transition significantly influences microbial life. Numerous studies revealed the important coupling relationship between microbial diversity and ecosystem functions in terrestrial ecosystems, however, the importance of microbial diversity in maintaining soil functions in coastal ecosystems remains poorly understood. Here, we studied the shifts of microbial communities and soil multifunctionality (SMF; nine functions related with C, N and P cycling) along a vegetation gradient in a salt marsh ecosystem and investigated the microbial diversity - ecosystem function relationship. The aboveground vegetation shifted from mud flat (MF) to Scirpus triqueter (SM) and then Phragmites australis (PA) with increasing distance away from the sea. Average approach showed that the SMF was much higher in halophytes covered zones including SM and PA than in MF. Structural equation model (SEM) analysis confirmed that vegetation was an important predictor on SMF besides moisture and organic carbon. Linear regression and multiple threshold methods showed that in MF and SM zones, fungal rather than bacterial richness was significantly and positively correlated with SMF, while in the PA zone microbial diversity did not relate with SMF. Random forest analysis identified several Ascomycota taxa with preference over marine environment as strong predictors of SMF. Taken together, our study lays the basis for a better understanding on the relationships between belowground microbial diversity and soil functions in coastal ecosystems.

Advances and Limitations of Next Generation Sequencing in Animal Diet Analysis.

Diet analysis is a critical content of animal ecology and the diet analysis methods have been constantly improving and updating. Contrary to traditional methods of high labor intensity and low resolution, the next generation sequencing (NGS) approach has been suggested as a promising tool for dietary studies, which greatly improves the efficiency and broadens the application range. Here we present a framework of adopting NGS and DNA metabarcoding into diet analysis, and discuss the application in aspects of prey taxa composition and structure, intra-specific and inter-specific trophic links, and the effects of animal feeding on environmental changes. Yet, the generation of NGS-based diet data and subsequent analyses and interpretations are still challenging with several factors, making it possible still not as widely used as might be expected. We suggest that NGS-based diet methods must be furthered, analytical pipelines should be developed. More application perspectives, including nutrient geometry, metagenomics and nutrigenomics, need to be incorporated to encourage more ecologists to infer novel insights on they work.

One-Pot Synthesis of B/P-Codoped Co-Mo Dual-Nanowafer Electrocatalysts for Overall Water Splitting.

Exploring electrocatalysts with satisfactory activity and durability has remained a long-lasting target for electrolyzing water, which is particularly significant for sustainable hydrogen fuel production. Here, we report a quaternary B/P-codoped transition metal Co-Mo hybrid as an efficient alternative catalyst for overall water splitting. The Co-Mo-B-P/CF dual nanowafers were deposited on a copper foam by double-pulse electrodeposition, which is favorable for achieving a nanocrystalline structure. The Co-Mo-B-P/CF catalyst shows a high catalytic activity along with good long-term stability in 1.0 M KOH solutions for both the hydrogen and oxygen evolution reactions, requiring 48 and 275 mV to reach 10 mA cm-2, respectively. The synergetic effect between Co-Mo and doped B and P elements is mainly attributed to the excellent bifunctional catalysis performance, while the dual-nanowafer structure endows Co-Mo-B-P with numerous catalytical active sites enhancing the utilization efficiency of atoms. Moreover, the catalytic capability of Co-Mo-B-P/CF as a bifunctional electrocatalyst for the overall water splitting is proved, with the current density of 10 mA cm-2 accomplished at 1.59 V. After the stability test for overall water splitting at 1.59 V for 24 h, the activity almost remains unchanged. The features of excellent electrocatalytic activity, simple preparation, and inexpensive raw materials for Co-Mo-B-P/CF as a bifunctional catalyst hold great potentials for overall water splitting.

Vinylene-bridged donor-acceptor type porous organic polymers for enhanced photocatalysis of amine oxidative coupling reactions under visible light.

Porous organic polymers (POPs), owing to their abundant porosity, high stability and well-tunable properties, are promising candidates as heterogeneous photocatalysts for organic transformations. Here we report two vinylene-bridged donor-acceptor (D-A) structural POPs (TpTc-POP and TbTc-POP) that are facilely constructed by the electron-rich triarylamine and electron-deficient tricyanomesitylene as key building blocks by the organic base catalyzed Knoevenagel condensation. Both TpTc-POP and TbTc-POP possess hierarchical meso- and micro-pores with a high surface area. Furthermore, the unsubstituted vinylene linkages of D-A moieties in their polymer backbones extend their π-conjugation and render their broad absorption range in the visible-light region. Thus, these DA-POPs exhibited highly effective photocatalytic activities for aerobic oxidative coupling of amines to imines under visible light irradiation. This study shows the great potential of conjugated POPs with a D-A structural feature in designing highly efficient and active heterogeneous photocatalytic systems.

Fe-N4 engineering of S and N co-doped hierarchical porous carbon-based electrocatalysts for enhanced oxygen reduction in Zn-air batteries.

The development of high-performance non-noble metal cathode catalysts is a cutting-edge approach for efficient energy conversion and storage devices. Here, we describe an in situ-formed template-assisted method to prepare a highly active yet stable electrocatalyst (FeSN-HPC) that possesses abundant Fe-N4 sites uniformly dispersed in S and N co-doped hierarchical porous carbon. Compared to commercial Pt/C in alkaline electrolyte, the sample FeSN-HPC displays superior and enhanced oxygen reduction reaction (ORR) activity (0.86 V of half-wave potential) and stability (only 14 mV degradation of half-wave potential after durability tests). The high electrocatalytic activity of FeSN-HPC mainly originates from the synergistic effect of efficient N dopants (such as pyridinic N, graphitic N, and FeII-N4) and the desirable hierarchical porous architecture. Expectedly, the primary Zn-air battery (ZAB) with FeSN-HPC as the cathode electrocatalyst exhibits an outstanding discharge performance, with a maximal power density of 200 mW cm-2. Additionally, the sample FeSN-HPC also has promising potential for application in solid and flexible ZABs.

Correction: Electrochemically shape-controlled synthesis of great stellated dodecahedral Au nanocrystals with high-index facets for nitrogen reduction to ammonia.

Correction for 'Electrochemically shape-controlled synthesis of great stellated dodecahedral Au nanocrystals with high-index facets for nitrogen reduction to ammonia' by Yu-Chen Jiang et al., Chem. Commun., 2020, DOI: 10.1039/d0cc04326e.

Materializing efficient methanol oxidation via electron delocalization in nickel hydroxide nanoribbon.

Achieving a functional and durable non-platinum group metal-based methanol oxidation catalyst is critical for a cost-effective direct methanol fuel cell. While Ni(OH)2 has been widely studied as methanol oxidation catalyst, the initial process of oxidizing Ni(OH)2 to NiOOH requires a high potential of 1.35 V vs. RHE. Such potential would be impractical since the theoretical potential of the cathodic oxygen reduction reaction is at 1.23 V. Here we show that a four-coordinated nickel atom is able to form charge-transfer orbitals through delocalization of electrons near the Fermi energy level. As such, our previously reported periodically arranged four-six-coordinated nickel hydroxide nanoribbon structure (NR-Ni(OH)2) is able to show remarkable methanol oxidation activity with an onset potential of 0.55 V vs. RHE and suggests the operability in direct methanol fuel cell configuration. Thus, this strategy offers a gateway towards the development of high performance and durable non-platinum direct methanol fuel cell.

Electrochemically shape-controlled synthesis of great stellated dodecahedral Au nanocrystals with high-index facets for nitrogen reduction to ammonia.

Au great stellated dodecahedra (GSD), one of the Kepler-Poinsot solids, are synthesized by an electrochemical double-step potential method in a choline chloride-urea based deep eutectic solvent. The as-synthesized Au GSD are bound by high-index {331} facets and exhibit excellent electrocatalytic performance for the nitrogen reduction reaction with a high NH3 yield rate (49.96 µg h-1 cm-2) and faradaic efficiency (28.59%) under ambient conditions.

Excavated cubic platinum-iridium alloy nanocrystals with high-index facets as highly efficient electrocatalysts in N2 fixation to NH3.

Excavated cubic Pt93Ir7 alloy nanocrystals enclosed by high-index {710} facets exhibit excellent electrocatalytic properties for the nitrogen reduction reaction (NRR) with a high faradaic efficiency (40.8%) and NH3 production rate (28 µg h-1 cm-2). The presence of Ir on the Pt stepped surface suppresses the hydrogen evolution reaction (HER) and accelerates the NRR.

Integrated N-Co/Carbon Nanofiber Cathode for Highly Efficient Zinc-Air Batteries.

In order to reduce the charge-transfer resistance, ohmic resistance, and ionic and electronic resistances arising from the polymer binder, designing and constructing self-standing and binder-free porous electrodes are very significant for energy storage and conversion devices. Herein, self-standing and binder-free porous N-Co carbon nanofiber (N-Co/CNF) cathodes are prepared for zinc-air batteries (ZABs) by an in situ electrospinning/plasma-etching method. The morphology and activity of the prepared electrodes are investigated by several characterization techniques. The prepared specimens exhibit a multilayered CNF structure, and a new CoN compound is produced after plasma-etching treatment. The N-Co/CNF-300-10 cathode demonstrates excellent electrocatalytic performance toward oxygen reduction reaction, with an onset potential and a half-wave potential of 0.995 and 0.853 V (vs reversible hydrogen electrode), respectively, which is comparable to that of 20% Pt/C. The N-Co/CNF-300-10 cathode acting as a self-standing electrode for ZABs exhibits a maximum discharge power density as high as 229 mW cm-2 and a specific capacity of 659.6 mA h gZn-1, which are much higher than those of the commercial catalysts, benefiting from the self-standing porous structure, N-doping, and more defects and active sites induced by plasma-etching. It provides an effective way to construct a self-standing porous electrode with controllable compositions for rechargeable metal-air batteries.