Carbon Substrate Research Articles

Atomic level dispersed nickel coupled with silver nanoparticle to boost the efficiency of CO2 conversion to CO via spin electrons regulation

Modulating the electronic configuration by coupling multi-scale active sites for electrocatalytic conversion of CO2 to CO is extremely challenging in terms of structural analysis and mechanism elucidation. Herein, a catalyst NiAD/AgNPs@CN with both atomic-level dispersed Ni and Ag nanoparticles on N-doped carbon substrate has been designed to reveal the true active sites and catalytic mechanism in complex materials. NiAD/AgNPs@CN exhibits CO Faraday efficiency (FECO) of 99.97% at −0.88 V (vs. RHE) in H-type cell and 91.77% FECO with a high current density of 79.70 mA/cm2 in flow cell. DFT calculations show that the tiny change in the energy level of spin electrons at atomic sites has a significant impact on the CO2 activation. The regulation of atomic Ni on Ag sites is the main reason for improving CO2RR performance. This work gives a new understanding on the catalytic mechanism of composite materials structured by atomic-level dispersed metal and nanoparticles.

Nickel ferrite coated on carbon felt for asymmetric supercapacitor

Nickel ferrite (NiFe2O4) is one of the nanostructures that has been the focus of researchers in the field of energy in recent years as an electrode, is conductive, stable, and cheap. In this research, for the first time, we have synthesized it using a felt carbon substrate. The synthesized electrode (NiFe2O4/CF) was evaluated by CV, GCD, and EIS in a three-electrode system using a KOH electrolyte. The results showed a specific capacity of 490 F/g at a current density of 1 A/g and a stability of 91.3 % after 5000 consecutive GCD cycles. Subsequent investigations were carried out in a two-electrode system for constructing an Asymmetrical supercapacitor using the NiFe2O4/CF and Active carbon electrodes. GCD analyses were conducted in a potential window of 1.5 V. The energy density and power density were determined as 39 Wh/kg and 410 W/kg Also, the use of activated carbon in the construction of the supercapacitor device improved the stability so that after 5000 consecutive charges and discharges, the constructed device showed 94.2 % stability. Finally, we examined the application of the supercapacitor made to keep the LED lamp on. We were able to keep the lamp on for 71 s.

High-Density CoSe2 Sites Embedded within 2D Porous N-Doped Carbon for High-Performance Oxygen Reduction Reaction Electrocatalysis.

Designing and fabricating efficient and stable nonprecious metal-based oxygen reduction reaction (ORR) electrocatalysts is a pressing and challenging task for the pursuit of sustainable new energy devices. Herein, porous P-CoSe2@NC electrocatalysts with high-density carbon-coated CoSe2 sites were successfully fabricated based on a pyridyl-porphyrinic metal-organic framework (Co-TPyP MOF) via a molten salt-assisted synthesis method. The hierarchical pore and N-doping carbon substrate of P-CoSe2@NC promotes mass transfer and electron-transfer efficiency, which is beneficial to maximize CoSe2 site utilization. Well-designed P-CoSe2@NC exhibits efficient ORR catalytic activity with a high half-wave potential of 0.863 V and excellent catalytic stability. Meanwhile, rechargeable aqueous primary/quasi-solid-state ZABs based on a P-CoSe2@NC air cathode show a high peak power density and exceptional operating stability, catering to the demands of practical applications. The qualified performance and structure stability of the electrocatalytic system may be mainly attributed to the protection of the CoSe2 nanoparticle by the coated carbon layer. Given the rational design of the structure and the component of the electrocatalyst with enhanced ORR activity, we believe that this work has provided a reliable pathway to the development of high-performance transition-metal chalcogenides for energy-storage and -conversion devices.

Geometric and Electronic Engineering in Co/VN Nanoparticles to Boost Bifunctional Oxygen Electrocatalysis for Aqueous/Flexible Zn-Air Batteries.

Modulating metal-metal and metal-support interactions is one of the potent tools for augmenting catalytic performance. Herein, highly active Co/VN nanoparticles are well dispersed on three-dimensional porous carbon nanofoam (Co/VN@NC) with the assistance of dicyandiamide. Studies certify that the consequential disordered carbon substrate reinforces the confinement of electrons, while the coupling of diverse components optimizes charge redistribution among species. Besides, theoretical analyses confirm that the regulated electron configuration can significantly tune the binding strength between the active sites and intermediates, thus optimizing reaction energy barriers. Therefore, Co/VN@NC exhibits a competitive potential difference (ΔE, 0.65 V) between the half-wave potential of ORR and OER potential at 10 mA cm-2, outperforming Pt/C+RuO2 (0.67 V). Further, catalyst-based aqueous/flexible ZABs present superior performances with peak power densities of 156 and 85 mW cm-2, superior to Pt/C-based counterparts (128 and 73 mW cm-2). This research provides a pivotal foundation for the evolution of bifunctional catalysts in the energy sector.

A validated pangenome-scale metabolic model for the Klebsiella pneumoniae species complex.

The Klebsiella pneumoniae species complex (KpSC) is a major source of nosocomial infections globally with high rates of resistance to antimicrobials. Consequently, there is growing interest in understanding virulence factors and their association with cellular metabolic processes for developing novel anti-KpSC therapeutics. Phenotypic assays have revealed metabolic diversity within the KpSC, but metabolism research has been neglected due to experiments being difficult and cost-intensive. Genome-scale metabolic models (GSMMs) represent a rapid and scalable in silico approach for exploring metabolic diversity, which compile genomic and biochemical data to reconstruct the metabolic network of an organism. Here we use a diverse collection of 507 KpSC isolates, including representatives of globally distributed clinically relevant lineages, to construct the most comprehensive KpSC pan-metabolic model to date, KpSC pan v2. Candidate metabolic reactions were identified using gene orthology to known metabolic genes, prior to manual curation via extensive literature and database searches. The final model comprised a total of 3550 reactions, 2403 genes and can simulate growth on 360 unique substrates. We used KpSC pan v2 as a reference to derive strain-specific GSMMs for all 507 KpSC isolates, and compared these to GSMMs generated using a prior KpSC pan-reference (KpSC pan v1) and two single-strain references. We show that KpSC pan v2 includes a greater proportion of accessory reactions (8.8 %) than KpSC pan v1 (2.5 %). GSMMs derived from KpSC pan v2 also generate more accurate growth predictions, with high median accuracies of 95.4 % (aerobic, n=37 isolates) and 78.8 % (anaerobic, n=36 isolates) for 124 matched carbon substrates. KpSC pan v2 is freely available at https://github.com/kelwyres/KpSC-pan-metabolic-model, representing a valuable resource for the scientific community, both as a source of curated metabolic information and as a reference to derive accurate strain-specific GSMMs. The latter can be used to investigate the relationship between KpSC metabolism and traits of interest, such as reservoirs, epidemiology, drug resistance or virulence, and ultimately to inform novel KpSC control strategies.

Multiple roles for the cytoplasmic C-terminal domains of the yeast cell surface receptors Rgt2 and Snf3 in glucose sensing and signaling

The plasma membrane proteins Rgt2 and Snf3 are glucose sensing receptors (GSRs) that generate an intracellular signal for the induction of gene expression in response to high and low extracellular glucose concentrations, respectively. The GSRs consist of a 12-transmembrane glucose recognition domain and a cytoplasmic C-terminal signaling tail. The GSR tails are dissimilar in length and sequence, but their distinct roles in glucose signal transduction are poorly understood. Here, we show that swapping the tails between Rgt2 and Snf3 does not alter the signaling activity of the GSRs, so long as their tails are phosphorylated in a Yck-dependent manner. Attachment of the GSR tails to Hxt1 converts the transporter into a glucose receptor; however, the tails attached to Hxt1 are not phosphorylated by the Ycks, resulting in only partial signaling. Moreover, in response to non-fermentable carbon substrates, Rgt2 and Hxt1-RT (RT, Rgt2-tail) are efficiently endocytosed, whereas Snf3 and Hxt1-ST (ST, Snf3-tail) are endocytosis-impaired. Thus, the tails are important regulatory domains required for the endocytosis of the Rgt2 and Snf3 glucose sensing receptors triggered by different cellular stimuli. Taken together, these results suggest multiple roles for the tail domains in GSR-mediated glucose sensing and signaling.

Effect and mechanism of PEDOT-Cu/Cu2O on the electrochemical reduction of nitrate with carbon electrodes

Electrochemical nitrate reduction for ammonia nitrogen (NH4+-N) generation is a promising method for resources recycling and relies on cheap and stable electrodes. In this study, carbon plate (CP), carbon felt (CF), and carbon brush (CB) were compared to identify their potential value on electrochemical nitrate reduction. By using the electrodeposition technique, copper-based nanometallic particles (Cu/Cu2O NPs) and poly-3,4-ethylenedioxythiophene (PEDOT) were loaded on the carbon substrates to prepare the (Cu/Cu2O) NPs/PEDOT/(Cu/Cu2O) NPs/CF electrode, which was tested in a single chamber electrolytic cell and subjected to continuous electrolysis of artificial wastewater (25–100 mg L−1 NO3--N) for 12 h. At a current density of 30 mA cm−2, the electrode achieved 97% nitrate removal and 81% NH4+-N selectivity. The synergistic catalytic interaction between Cu/Cu2O NPs and PEDOT improved the electrode reduction activity and NH4+-N selectivity, and had a good H* providing ability as noble metals. This provides a new method for nitrate reduction and NH4+-N recovery.

Boosted carbon electrocatalytic effect towards sensing and green energy applications by tailoring the catalyst-support interface on a nature-inspired solution

Carbon electrodes are widely accepted as very versatile platforms, with applications ranging from electrocatalysis to sensors and other devices, like fuel cells and water electrolyzers. However, there are still difficulties given that over time, at high potentials, the oxidation of carbon materials (as a catalyst and/or catalyst support) can play a detrimental role, undermining the efficiency and stability of the electrochemical processes and devices performance. In this paper, it is reported the research work followed by resourcing to electrochemical analytical techniques, like cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), along with complementary atomic force microscopy (AFM) and water contact angle (WCA) measurements. These techniques were used to characterise glass-type and paper-based carbon electrodes. On a nature-inspired solution, we took advantage of the different interfacial carbon-support hierarchical porous structures to boost the carbon electrocatalytic effect towards sensing the ferri/ferrocyanide redox couple ([Fe(CN)6]3-/4−) in aqueous solution. It is shown that the best results were achieved with carbon paper electrodes without wet proofing, given its hierarchical porous structure and absence of the insulating binder. This research endeavors to contribute to the ongoing advancements in the field of electrochemical green energy conversion by exploring innovative approaches and materials, with the ultimate aim of developing carbon substrates that not only enhance performance but also promote environmental sustainability.

Phenogenetic profile and agronomic contribution of Azospirillum argentinense Az39T, a reference strain for the South American inoculant industry

Azospirillum sp. is a plant growth-promoting rhizobacteria largely recognized for its potential to increase the yield of different important crops. In this work, we present a thorough genomic and phenotypic analysis of A. argentinense Az39T to provide new insights into the beneficial mechanisms of this microorganism. Phenotypic analyses revealed the following in vitro abilities: growth at 20–38 °C (optimum, 28 °C), pH 6.0–8.0 (optimum, pH 6.8), and in the presence of 1% (w/v) NaCl; production of variable amounts of PHB as intracellular granules; nitrogen fixation under microaerophilic conditions; IAA synthesis in the presence of L-tryptophan. Through biochemical (API 20NE) and carbon utilization profiling (Biolog) assays, we proved that A. argentinense Az39T is able to use 15 substrates and metabolize 19 different carbon substrates. Lipid composition indicated a predominance of medium and long-chain saturated fatty acids. A total of 6 replicons classified as one main chromosome, three chromids, and two plasmids, according to their tRNA and core essential genes contents, were identified. Az39T genome includes genes associated with multiple plant growth-promoting (PGP) traits such as nitrogen fixation and production of auxins, cytokinin, abscisic acid, ethylene, and polyamines. In addition, Az39T genome harbor genetic elements associated with physiological features that facilitate its survival in the soil and competence for rhizospheric colonization; this includes motility, secretion system, and quorum sensing genetic determinants. A metadata analysis of Az39T agronomic performance in the pampas region, Argentina, demonstrated significant grain yield increases in wheat and maize, proving its potential to provide better growth conditions for dryland cereals. In conclusion, our data provide a detailed insight into the metabolic profile of A. argentinense Az39T, the strain most widely used to formulate non-legume inoculants in Argentina, and allow a better understanding of the mechanisms behind its field performance.

Designing of Lightweight and Ultrathin III‐V/Ge Solar Cells for Flexible Space and Terrestrial Photovoltaic Blankets

The method described in this article offers a simple and convenient way to obtain highly efficient, ultrathin, and flexible solar cells (SCs) based on III‐V/Ge heterostructures. This is achieved by thinning Ge to several tens, or even a few units of microns, which accounts for up to 95% of the total thickness and weight of a SC. The only low‐temperature thermal peelable tape REVALPHA as a temporary carrier supports and saves the heterostructure along the process route. The carrier is then easily and cleanly removed by heating without damaging the thinned SC. The temporary carrier provides a reliable transfer of the thinned SC with a developed low‐temperature (i.e., without annealing) indium back contact to an arbitrary light and flexible substrate (Kapton or carbon sheet). The possibility of creating highly efficient, ultrathin, and ultralight SCs on a flexible carrier is demonstrated using mass‐produced GaInP/Ga(In)As/Ge heterostructures. Based on the results obtained, a possible architecture and technology for assembling coupons from ultrathin solar cells based on any III‐V/Ge heterostructures on a Kapton or carbon carrier for space and terrestrial applications are proposed.

The deposition properties of tetrahedral amorphous carbon coatings deposited on piston ring: Molecular dynamics simulation

The tetrahedral amorphous carbon (ta-C) coatings are deposited on piston rings to improve the tribological property of the piston ring-cylinder liner system of the internal combustion engines. The deposition parameters are optimized by molecular dynamics simulation to reduce the cost of coatings’ fabrication. The ta-C coatings with higher sp3 fraction, lower friction coefficient, and superior anti-wear properties are achieved by optimizing the incident energy and substrate temperature of carbon atoms. The second nearest-neighbor modified embedded-atom method potential and Tersoff potential are used to describe the interatomic interactions. The effects of the incident energy of the carbon atoms and substrate temperature on the deposition properties of the ta-C coatings are discussed. The numerical results show that the ta-C coatings with high sp3 fraction, high density, and good interface mixing are obtained, and the deposition properties of the ta-C coatings are improved.

Alkaline wet oxidative pretreatment and acid hydrolysis of wheat straw for squalene and monomethyl branched chain fatty acids rich lipid production in Lentibacillus salarius BPIITR

Lignocellulosic biomass has high potential for use as a carbon substrate in microbial fermentation. However, the generation of various lignin-derived phenolic compounds, benzoic acids, and carbohydrate-derived furan aldehydes poses a major bottleneck. In this study, wheat straw was subjected to sequential alkaline wet oxidative pretreatment (AWOP) and acid hydrolysis to extract hemicellulose sugars. After statistical optimization, 251.50 mg/g total sugar (228.57 mg/g pentose, 22.93 mg/g hexose) and 19.64 mg/g hydrolysis by-products were achieved, with a theoretical pentose recovery of 89.57% and residual cellulose of 72.1%. The lignin-rich and carbohydrate-rich liquids from the AWOP treatment and acid hydrolysis, respectively, were valorised to produce squalene and branched chain fatty acid rich lipid using Lentibacillus salarius BPIITR. The lipid of 100.9 ± 3.53 and 235.75 ± 10.39 mg/g of dcw rich in squalene up to 3121.17 ± 25.49 and 676.41 ± 134.27 μg/g of lipid was produced in AWOP and acid hydrolysate, respectively. In the AWOP hydrolysate, lignin content was reduced by 63.78%, compared to a 40.18% reduction in the acid hydrolysate. GC-MS analysis of the lignin monomer and metabolites suggests the potential influence of lignin monomers on the biosynthetic pathway of squalene and carbohydrate content on the branched chain fatty acids accumulation in the halophilic bacterial lipid of L. salarius BPIITR.

Ru-Doped Ultrasmall Cu Nanoparticles Decorated with Carbon for Electroreduction of Nitrate to Ammonia.

Electrocatalytic nitrate reduction reaction offers a sustainable approach to treating wastewater and synthesizing high-value ammonia under ambient conditions. However, electrocatalysts with low faradaic efficiency and selectivity severely hinder the development of nitrate-to-ammonia conversion. Herein, Ru-doped ultrasmall copper nanoparticles loaded on a carbon substrate (Cu-Ru@C) were fabricated by the pyrolysis of Cu-BTC metal-organic frameworks (MOFs). The Cu-Ru@C-0.5 catalyst exhibits a high faradaic efficiency (FE) of 90.4% at -0.6 V (vs RHE) and an ammonia yield rate of 1700.36 μg h-1mgcat.-1 at -0.9 V (vs RHE). Moreover, the nitrate conversion rate is almost 100% over varied pHs (including acid, neutral, and alkaline electrolytes) and different nitrate concentrations. The remarkable performance is attributed to the synergistic effect between Cu and Ru and the excellent conductivity of the carbon substrate. This work will open an exciting avenue to exploring MOF derivatives for ambient ammonia synthesis via selective electrocatalytic nitrate reduction.

Transient anoxic conditions boost N2O emissions by stimulating denitrification capacity and decreasing N2O reduction ratio in soils with different carbon substrates

Quantitative identification of the dominant N2O production and consumption processes following sudden shifts in soil aeration in well-aerated soils is limited, lagging the development of N2O mitigation strategies. Nitrous oxide emissions from agricultural soils, the largest source of anthropogenic N2O, are strongly influenced by low-molecular-weight organic carbons from root exudates (RootEx). In this study, we conducted a laboratory incubation experiment to investigate the mechanisms of N2O emissions regulated by transient anoxic conditions under the effects of different carbon substrates. Three common components in RootEx, oxalic acid, serine, and glucose were individually added as carbon sources every 24 h to the sandy loam soil. The contribution of microbial processes to N2O production (fungal denitrification, nitrification, bacterial denitrification) and consumption (N2O reduction) was evaluated using a dual isotope mapping approach (SP/δ18O MAP). The result indicated that transient anoxic conditions stimulated N2O production primarily through bacterial denitrification process facilitated by carbon substrates, and diminished the proportion of N2O reduction compared to oxic conditions. Among the three components of RootEx, serine and glucose induced higher N2O emissions and N2O reduction rates than oxalic acid during incubation. The differential effects of these three components on N2O emissions imply that the regulatory effect of carbon substrates on N2O reduction could not counterbalance the influence of transient anoxic conditions on N2O stimulation. Our findings provide a fundamental understanding of the effects of transient anoxic conditions and RootEx on N2O stimulation, facilitating the study of the spatial and temporal heterogeneity of N2O emissions in response to soil aeration changes in various upland soils.

Effects of energized treatment on electro trigger shape memory behavior

The shape memory polymers (SMPs) can be programmed to take temporary shapes and return to their original shape when subjected to external stimuli. Electrically triggered SMP has become an important branch of shape memory materials because of its advantages such as remote heating, fast response and local control. In this paper, a novel shape memory composite structure is prepared by using polylactic acid (PLA) as substrate and short carbon fiber (SCF) as conductive filler. The electrification treatment during the preparation process has a beneficial effect on the SCF arrangement. Compared with the sample without electrification treatment, the highest conductivity can be increased from 43.96 S/m to 66.67 S/m, and the performance is improved by 51.66 %. When the voltage is increased from 3 V to 8 V, the time to reach the glass transition temperature (Tg) is reduced by 62.22 %, and the shape memory recovery time is reduced by 53.68 %. The intelligent fixture based on the composite structure can realize the remote grasp of 3D printed balls with a diameter of 40 mm and a weight of 18.35 g under pressure, which fully proves the reliable electrically triggered shape memory performance of the composite structure and the great application potential in the field of robot gripper.

The hidden roots of wetland methane emissions.

Wetlands are the largest natural source of methane (CH4 ) globally. Climate and land use change are expected to alter CH4 emissions but current and future wetland CH4 budgets remain uncertain. One important predictor of wetland CH4 flux, plants, play an important role in providing substrates for CH4 -producing microbes, increasing CH4 consumption by oxygenating the rhizosphere, and transporting CH4 from soils to the atmosphere. Yet, there remain various mechanistic knowledge gaps regarding the extent to which plant root systems and their traits influence wetland CH4 emissions. Here, we present a novel conceptual framework of the relationships between a range of root traits and CH4 processes in wetlands. Based on a literature review, we propose four main CH4 -relevant categories of root function: gas transport, carbon substrate provision, physicochemical influences and root system architecture. Within these categories, we discuss how individual root traits influence CH4 production, consumption, and transport (PCT). Our findings reveal knowledge gaps concerning trait functions in physicochemical influences, and the role of mycorrhizae and temporal root dynamics in PCT. We also identify priority research needs such as integrating trait measurements from different root function categories, measuring root-CH4 linkages along environmental gradients, and following standardized root ecology protocols and vocabularies. Thus, our conceptual framework identifies relevant belowground plant traits that will help improve wetland CH4 predictions and reduce uncertainties in current and future wetland CH4 budgets.

Efficient and Stable Dual-Active-Site of Core-Shell NiFe-Layered Double Hydroxide Anchored on FeMnON-N-Doped Carbon Nanotubes as Bifunctional Oxygen Electrocatalysts for Zn-Air Batteries

The bifunctional air electrodes with numerous dual-active sites and low cost are desirable to modify the performance of Zn-air batteries (ZABs). Metal–oxygen-nitrogen–carbon substrate (M = Mn, Fe, Ni, etc.) and NiFe-layered double hydroxide (NiFe-LDH) nanosheets are excellent catalysts in the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) processes, respectively. Hereby, we investigate a bifunctional electrocatalytic substrate with a 3D core–shell hierarchical architecture by anchoring high OER-active NiFe-LDH on ORR-active FeMnZIF-8@gC3N4-derived FeMnON-N doped carbon nanotubes bamboo like (NiFe-LDH@FeMnON-NC). This nanocomposite has unique features such as robust synergistic effects, high conductivity, balance, and optimization of surface chemical valences of Fe, Mn, and Ni atoms to boost the bifunctional ORR and OER properties and stability in ZABs. The NiFe-LDH@FeMnON-NC nanocomposite not only exhibited superior OER electroactivity with a low onset overpotential of 235 mV (10 mA cm−2) but also had excellent ORR activity with a current density of −5.48 mA cm−2 and onset potential of 1.04 V, which is better than or comparable to those of commercial Pt/C and RuO2. Rechargeable ZABs constructed by bifunctional NiFe-LDH@FeMnON-NC have a peak power density (235.41 mW cm−2), open-circuit potential (OCV) (1.53 V), small discharge/charge band gap of 0.74 V and excellent discharge stability.

Switchgrass (Panicum virgatum L.) cultivars have similar impacts on soil carbon and nitrogen stocks and microbial function

AbstractSwitchgrass (Panicum virgatum L.) production for biofuel has the potential to produce reasonable yields on lands not suited for conventional agriculture. We assessed nine switchgrass cultivars representing lowland and upland ecotypes grown for 11 years at a site in the upper Midwest USA for belowground differences in soil carbon and nitrogen stocks, soil organic matter fractions, and standing root biomass to 1 m depth. We also compared potential nitrogen mineralization and carbon substrate use through community‐level physiological profiling in surface soils (0–10 cm depth). Average yields and standing root biomass differed among cultivars and between ecotypes, but we found no significant cultivar‐related impacts on soil carbon and nitrogen stocks, on the distribution of particulate and mineral‐associated soil organic matter fractions, nor on potential nitrogen mineralization or microbial community‐level physiological profiles. That these traits did not differ among cultivars suggests that soil carbon and nitrogen gains under switchgrass are likely to be robust with respect to cultivar differences, and to this point not much affected by breeding efforts.

F Doping-Induced Multicomponent Synergistic Active Site Construction toward High-Efficiency Bifunctional Oxygen Electrocatalysis for Rechargeable Zn-Air Batteries.

The commercialization of rechargeable Zn-air batteries (ZABs) relies on the material innovation to accelerate the sluggish oxygen electrocatalysis kinetics. Due to the differentiated mechanisms of reverse processes, i.e., oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), rationally integrating dual sites for bifunctional oxygen electrocatalysis is prerequisite yet remains challenging. Herein, multicomponent synergistic active sites within highly graphitic carbon substrate are exquisitely constructed, which is accomplished by fluorine (F) modulation strategy. The incorporation of F dopants facilitates pyridinic N formation for anchoring single metal sites, thus guaranteeing the coexistence of sufficient M-Nx sites and metal nanoparticles toward bifunctional oxygen electrocatalysis. As a result, the optimal catalyst, denoted as F NH2-FeNi-800, outperforms commercial Pt/C+RuO2 with smaller gap between Ej = 10 and E1/2 (ΔE) of 0.63V (vs 0.7V for Pt/C+RuO2), demonstrating its superior bifunctionality. Beyond that, its superiority is validated in homemade rechargeable ZABs. ZABs assembled using F NH2-FeNi-800 as the air cathode delivers higher peak power density (123.8mW cm-2) and long-cycle lifetime (over 660 cycles) in comparison with Pt/C@RuO2 (68.8mW cm-2; 300 cycles). The finding not only affords a highly promising oxygen electrocatalyst, but also opens an avenue to constructing multifunctional active sites for heterogeneous catalysts.

Catalytic Enantioselective Protonation of Gold Enolates Enabled by Cooperative Gold(I) Catalysis.

Enantioselective protonation is a versatile approach to the construction of tertiary α-stereocenters, which are common structural motifs in various natural products and biologically relevant compounds. Herein we report a mild access to these chiral centers using cooperative gold(I) catalysis. From cyclic ketone enol carbonates, this asymmetric catalysis provides highly enantioselective access to cyclic ketones featuring an α tertiary chiral center, including challenging 2-methylsuberone. In combination with the gold-catalyzed formation of cyclopentadienyl carbonates in a one-pot, two-step process, this chemistry enables expedient access to synthetically versatile α'-chiral cyclopentenones with excellent enantiomeric excesses from easily accessible enynyl carbonate substrates.