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Controlled synthesis of dual-atom catalysts (DACs) for heterogeneous catalytic reactions is vital but still demanding. Herein, we construct a novel dual-atom catalyst containing FeN3-CoN3sites on N-doped graphene nanosheets (CoFe-NG), which exhibits remarkable catalytic performance with a half-wave potential of 0.952 V for oxygen reduction reaction (ORR) and shows higher endurance to methanol/carbon monoxide poisoning and better durability than commercial Pt/C. The assembled Zn-air battery with CoFe-NG as the air electrode delivers a peak power density of 230 mW cm–2and exhibits negligible change in output voltage at 5 mA cm–2for 250 h. Theoretical calculations reveal that FeN3-CoN3sites on N-doped graphene exhibit lower ORR barrier than FeN4and CoN4sites, and the rate-limiting step on the former is the transformation of *OH intermediate to H2O, different from the transformation of *O to *OH on the FeN4site and the transformation of O2to *OOH on the CoN4site.

Ammonia is an important environmental pollutant that is toxic to most aquatic animals, and nutrient manipulation is an effective regulatory pathway. To assess the influence of taurine supplementation on growth, liver detoxification and anti-bacterial infection of yellow catfish subjected to ammonia exposure for a long time, three experiment diets with different taurine levels (0.50, 1.00, and 2.00 %) were formulated and fed to fish (7.28 ± 0.05) g under three ammonia levels (0.00, 25.00 and 50.00 mg/L total ammonia nitrogen) for 56 days. The results showed that hepatic glycogen and whole-body protein contents were reduced, suggesting that energy deficiency caused by ammonia poisoning plays an important role in growth inhibition; elevated serum alanine aminotransferase and aspartate aminotransferase levels suggest liver injury, which may be caused by oxidative stress (decreased activities of superoxide dismutase and catalase, and expressions of SODand CAT) and inflammation (increased contents of tumor necrosis factor α, interleukin 1 and interleukin 8, and expressions of TNF α, IL 1and IL8), analysis of tissue sections further confirmed this finding. Furthermore, after injection with Aeromonas hydrophila, cumulative mortality increased proportionally with the rise in ammonia levels, the observed decrease in serum complements C3, C4, immunoglobulin M, and antibody titer contents emerged as a crucial factor contributing to the decreased disease resistance. The exogenous taurine was found to alleviate the negative impact of the above-mentioned ammonia poisoning. This study provides valuable insights into the mechanism of ammonia-induced aquatic toxicology in fish.

The exploration of efficient and earth-rich electrocatalysts for electrochemical reactions is critical to the implementation of large-scale green energy conversion and storage techniques. Two-dimensional (2D) materials with distinctive structural and electrochemical properties provide fertile soil for researchers to harvest basic science and emerging applications, which can be divided into metal-free materials (such as graphene, carbon nitride and black phosphorus) and transition metal-based materials (such as halogenides, phosphates, oxides, hydroxides, and MXenes). For faultless 2D materials, they usually exhibit poor electrochemical hydrogen evolution reaction (HER) activity because only edge sites can be available while the base surface is chemically inactive. Defect engineering is an effective strategy to generate active sites in 2D materials for improving electrocatalytic activity. This review presents feasible design strategies for constructing defect sites (including edge defects, vacancy defects and dopant derived defects) in 2D materials to improve their HER performance. The essential relationships between defect structures and electrocatalytic HER performance are discussed in detail, providing valuable guidance for rationally fabricating efficient HER electrocatalysts. The hydrogen adsorption/desorption energy can be optimized by constructing defect sites at different locations and by adjusting the local electronic structure to form unsaturated coordination states for efficient HER.

While the study on the aqueous asymmetric capacitor of activated carbon/copper oxide has reached a relatively mature stage, further progress in the technology relies on overcoming specific issues. This paper proposes and eliminates a detrimental crosstalk between the CuO cathode and AC anode, which impairs the cyclic performance of capacitor. During the charging process, Cu2+dissolves from the CuO cathode and deposits as Cu/Cu2O crystals on the surface of AC anode. These deposits obstruct the pores of activated carbon and then diminish the specific surface area of the electric double layer, consequently decreasing capacitance performance of capacitors. The capacitors demonstrate a remarkable enhancement in cycle life by adding an anion exchange membrane between two electrodes to shut off this crosstalk. After 10,000 cycles at 1 A g−1, the capacity retention rate of AC/CuO capacitors is increased by 36.6 %, reaching 94.1 %. Even at higher current densities, the capacitors maintain superior cyclic stability. This study is a significant stride in aqueous asymmetric capacitors.

Micro(nano)plastics (MNPs) are a growing problem as persistent environmental pollutants. Here, we investigated the impact of MNPs on microorganisms in aquatic microbial floc exposed to NPs (80 ​nm) and MPs (8 ​μm) for 35 days. Water quality indicators were tested weekly and microbiological analyses were conducted on Day 7 and 28 after exposure. The results showed that there were significant differences in the levels of total ammonia nitrogen or nitrite between the MNPs groups and the control group, spanning from Day 7 to Day 28. For the microbial response, microbial community richness in the NPs and MPs groups were significantly increased at Day 7. Functional prediction showed that the relative abundances of bacteria associated with the “Forms Biofilms”, “Potentially Pathogenic”, “Plastic Degradation” and nitrogen cycle processes were significantly different after MNPs exposure. The results suggest that MNPs had no significant effect on the microbial diversity of mature microbial flocs. Findings suggest MPs could cause an increase in the relative abundance of potentially pathogenic bacteria, while NPs do not. In addition, stress associated with MNPs affected the nitrogen cycle of microorganisms, and NPs exerted greater impacts than MPs. Findings from this study further our understanding of the impact of MNPs at environmentally relevant concentrations on microorganisms in aquatic ecosystems.

Copper is the only metal that can convert CO2into C2 and C2+ in electrocatalytic carbon dioxide reduction (CO2RR). However, the Faraday efficiency of CO2conversion to C2 and C2+ products at high current densities is still low, which cannot meet the actual industrial demand. Here, the design methods of single‐atom copper catalysts (including regulating the coordination environment of single‐atom copper, modifying the carbon base surface and constructing diatomic Cu catalysts) are reviewed, and the current limitations and future research directions of copper‐based single‐atom catalysts are proposed, providing directions for the industrial conversion of CO2into C2 and C2+ products. The design strategies of single‐atom copper catalysts are briefly summarized and the key factor for their application in industrially electrochemical conversion of CO2into C2 and C2+ products are pointed out.

The effects of gamma-aminobutyric acid (GABA) on aquatic animals remain to be explored. Here, we conducted GABA addition tests, both in water and in feed, as well as ammonia stress tests using Micropterus salmoides(M. salmoides). The tissue structure and indicators associated with the oxidative state of M. salmoideswere evaluated to assess the effects. The results showed that, the levels of alanine aminotransferase, alkaline phosphatase, and total antioxidant capacity in most of the GABA water addition groups were lower than those in the control group at 96 h after the addition of GABA. In the gill of feed addition groups (GL: 30 mg kg−1; GM: 90 mg kg−1; GH: 150 mg kg−1), the contents of glutathione (GSH) in the GH group were significantly higher when compared with their control group (CK group: 0 mg kg−1) at day 12 and day 15. In the following ammonia stress test, the tissue damage of the gill, brain, and kidney were alleviated in the GM and GH groups. The GSH contents of all tissues in all groups decreased gradually with the prolongation of the stress time. Conversely, the malondialdehyde (MDA) and nitric oxide (NO) contents have the opposite trend. The results suggested that GABA addition in water may not be applicable in actual aquaculture. The inclusion of GABA in the feed at concentrations of 90 and 150 mg kg−1contributed to improving the ammonia resistance of M. salmoidesby reducing tissue damage and the inflammatory response, as well as improving the antioxidant status. Moreover, the gill might be the target tissue protected by GABA in M. salmoidesunder ammonia stress. These results could enrich our basic understanding of the effect of GABA on aquatic animals and help us find possible ways to solve the environmental stress problems in aquaculture.

A series of Ce-SBA-15 mesoporous materials were synthesized through a direct hydrothermal method and further impregnated with different amounts of Cs. The catalysts were characterized by XRD, XPS, SEM, NH3-TPD, CO2-TPD, FT-IR and N2adsorption–desorption isotherm analyses. The XRD and N2adsorption–desorption isotherm results showed that the Ce successfully incorporated into the framework of SBA-15, which was favorable for the generation of mesoporous materials with high specific surface areas, large pore volumes and narrow pore size distribution. The incorporation of Ce changed the acid–base properties of the support and promoted the dispersion of Cs species. NH3–CO2TPD results indicated that a number of medium-strong acid and base sites existed in the 10Cs/Ce-SBA-15(10) catalyst, which made it suitable as a catalyst for the aldol condensation of methyl acetate with formaldehyde to prepare methyl acrylate.

Nb-doped vanadium phosphorus oxide catalysts were prepared and characterized using a variety of methods, including XRD, FT-IR, XPS, TPD and BET. The catalysts were examined for their ability to promote the aldol condensation of acetic acid with formaldehyde to acrylic acid. Catalyst composition and the conditions used to prepare the catalysts were investigated for their effects on catalytic activity. The addition of Nb changes the properties and catalytic properties of the catalyst to some extent, especially the surface acidity of catalyst and the average valence of surface V atoms, which have the greatest influence on the catalyst. When Nb/V = 0.06, the catalyst surface has the greatest acidity, the valence of surface V atoms is the lowest, and the selectivity (83.4%) and yield of acrylic acid (18.1%) are maximized.

Covalent organic frameworks (COFs) have become the most attractive frontier research field in heterogeneous catalysis. Since the geometric and electronic structures of COFs depend greatly on their microenvironment, which, in turn, determine the performances in electrocatalytic processes, the precise integration of atoms of building blocks of COFs to achieve pre-designed compositions, components and functions is the core. In this review, we focus on the latest progress in the structural design, synthesis, characterizations and applications of COFs, with emphasis on electrocatalytic mechanisms. Furthermore, we have proposed a variety of optimizing strategies including structural regulation (including building unit, linkage, and topological structure), pore surface engineering, side chain modification engineering, regulating non-metallic sites, regulating metal sites, regulating single metal active sites, defect engineering, and regulating composite materials to improve the electrocatalytic intrinsic activities of COFs. Experimental and theoretical advances in understanding such microenvironment in association to the electrocatalytic activity and mechanisms are exemplified in the electrochemical applications, including H2/O2evolution reactions and O2/CO2reduction reactions. Finally, by highlighting the prospects and challenges for structural regulations of COFs, we wish to shed some light on the further development of COFs for electrocatalysis applications.

The Prins condensation of isobutylene with formaldehyde over scillica-supported silicotungstic acid catalysts has been investigated. The catalysts were characterized via XRD, FTIR, Py-IR, NH3-TPD and TG–DSC techniques. It was found that the catalyst with 5 wt% silicotungstic acids loading exhibited the best isobutene conversion and isoprene selectivity, and excessive silicotungstic acid was not conducive to improve the catalytic performance. It was proposed that the concentration and strength of acid sites could affect the catalytic properties. An appropriate amount of weak Lewis acid sites were the active site for the condensation of isobutene with formaldehyde, and the medium-strong acid sites could cause the side reactions and coke deposits.

Abstract: The reaction of direct transformation of ethanol to ethyl acetate was investigated on reduced Cu/ZrO2 catalysts prepared by a co-precipitation procedure. The catalytic performances of these Cu–Zr mixed oxides were considerably influenced by changing the molar ratio of Cu to Zr. The highest selectivity to ethyl acetate was found over Cu/ZrO2(1) catalyst (molar ratio of Cu to Zr was 1). A variety of characterization techniques, such as N2 adsorption, XRD, XPS, TPR and NH3-TPD were carried out on the catalysts. The results revealed that the presence of a certain amount of Cu+ species may play very important role in improving the selectivity to ethyl acetate of the Cu/ZrO2 catalysts.

Abstract: The catalytic properties of supported Cu/SBA-15 catalysts prepared by the ion-exchange method were investigated for the hydrogenolysis of glycerol in a fixed-bed tubular reactor. The Cu/SBA-15 catalyst performed higher selectivity to 1,2-propanediol and high stability. We propose that the larger specific surface area and the ordered mesoporous channels of SBA-15 may play important roles in stabilizing highly dispersed copper species, and forming an active and durable catalyst for the title reaction.

Global cerebral ischemia induced by cardiac arrest usually leads to poor neurological outcomes. Numerous studies have focused on ways to prevent ischemic damage in the brain, however clinical therapies are still limited. Our previous studies revealed that delta opioid receptor (DOR) activation with [d-Ala2, d-Leu5] enkephalin (DADLE), a DOR agonist, not only significantly promotes neuronal survival on day 3, but also improves spatial memory deficits on days 5-9 after ischemia. However, the neurological mechanism underlying DADLE-induced cognitive recovery remains unclear. This study first examined the changes in neuronal survival in the CA1 region at the advanced time point (day 7) after ischemia/reperfusion (I/R) injury and found a significant amelioration of damaged CA1 neurons in the rats treated with DADLE (2.5 nmol) when administered at the onset of reperfusion. The structure and function of CA1 neurons on days 3 and 7 post-ischemia showed significant improvements in both the density of the injured dendritic spines and the basic transmission of the impaired CA3-CA1 synapses following DADLE treatment. The molecular changes involved in DADLE-mediated synaptic modulation on days 3 and 7 post-ischemia implied the time-related differential regulation of PKCα-MARCKS on the dendritic spine structure and of BDNF- ERK1/2-synapsin I on synaptic function, in response to ischemic/reperfusion injury as well as to DADLE treatment. Importantly, all the beneficial effects of DADLE on ischemia-induced cellular, synaptic, and molecular deficits were eliminated by the DOR inhibitor naltrindole (2.5 nmol). Taken together, this study suggested that DOR activation-induced protective signaling pathways of PKCα-MARCKS involved in the synaptic morphology and BDNF-ERK-synapsin I in synaptic transmission may be engaged in the cognitive recovery in rats suffering from advanced cerebral ischemia.