Metal Catalytic Activity Research Articles

A Highly Conjugated Nickel(II)-Acetylide Framework for Efficient Photocatalytic Carbon Dioxide Reduction.

The incorporation of transition-metal single atoms as molecular functional entities into the skeleton of graphdiyne (GDY) to construct novel two-dimensional (2D) metal-acetylide frameworks, known as metalated graphynes (MGYs), is a promising strategy for developing efficient catalysts, which can combine the tunable charge transfer of GDY frameworks, the catalytic activity of metal and the precise distribution of single metallic centers. Herein, four highly conjugated MGY photocatalysts based on NiII, PdII, PtII, and HgII were synthesized for the first time using the 'bottom-up' strategy through the use of M-C bonds (-C≡C-M-C≡C-). Remarkably, the NiII-based graphyne (TEPY-Ni-GY) exhibited the highest CO generation rate of 18.3 mmol g-1 h-1 and a selectivity of 98.8 %. This superior performance is attributed to the synergistic effects of pyrenyl and -C≡C-Ni(PBu3)2-C≡C- moieties. The pyrenyl block functions as an intramolecular π-conjugation channel, facilitating kinetically favorable electron transfer, while the -C≡C-Ni(PBu3)2-C≡C- moiety serves as the catalytic site that enhances CO2 adsorption and activation, thereby suppressing competitive hydrogen evolution. This study provides a new perspective on MGY-based photocatalysts for developing highly active and low-cost catalysts for CO2 reduction.

A Highly Conjugated Nickel(II)‐Acetylide Framework for Efficient Photocatalytic Carbon Dioxide Reduction

AbstractThe incorporation of transition‐metal single atoms as molecular functional entities into the skeleton of graphdiyne (GDY) to construct novel two‐dimensional (2D) metal‐acetylide frameworks, known as metalated graphynes (MGYs), is a promising strategy for developing efficient catalysts, which can combine the tunable charge transfer of GDY frameworks, the catalytic activity of metal and the precise distribution of single metallic centers. Herein, four highly conjugated MGY photocatalysts based on NiII, PdII, PtII, and HgII were synthesized for the first time using the ‘bottom‐up’ strategy through the use of M−C bonds (−C≡C−M−C≡C−). Remarkably, the NiII‐based graphyne (TEPY‐Ni‐GY) exhibited the highest CO generation rate of 18.3 mmol g−1 h−1 and a selectivity of 98.8 %. This superior performance is attributed to the synergistic effects of pyrenyl and −C≡C−Ni(PBu3)2−C≡C– moieties. The pyrenyl block functions as an intramolecular π‐conjugation channel, facilitating kinetically favorable electron transfer, while the −C≡C−Ni(PBu3)2−C≡C− moiety serves as the catalytic site that enhances CO2 adsorption and activation, thereby suppressing competitive hydrogen evolution. This study provides a new perspective on MGY‐based photocatalysts for developing highly active and low‐cost catalysts for CO2 reduction.

Atomic decoration of MoS2 using Fe, Co or Ni for highly efficient and selective hydrodesulfurization

Hydrodesulfurization (HDS) is one of the most efficient processes for removing sulfur-containing molecules such as dibenzothiophene (DBT) from oil, whatever fossil based or bio-based. However, hydrodesulfurization using molybdenum sulfides (MoS2) as catalytic active centers and transition metals (X) as promoters is seriously challenged by the insufficient catalytic activity and selectivity because of the separate phases of sulfides, and sparse X-Mo-S active sites, leading to poor synergistic effect between the X promoter and MoS2 active centers. Herein, atomically doped MoS2 catalysts (denoted as XMo, X = Fe, Co or Ni) were synthesized by using polyoxometalate template-based synthetic strategy were proposed. The pre-organized Anderson-type POMs, [XMo6O24H6]n− (X = Fe, Co or Ni), acted as a pre-assembled molecular platform with intimate X-Mo interactions, ensure the uniform formation of X-Mo-S active sites after sulfuration. The promoter atoms, including Fe, Co and Ni, enhanced the efficiency of hydrodesulfurization of MoS2. Particularly, NiMo exhibits the highest HDS activity, while CoMo shows a moderate HDS activity with the highest DDS selectivity (∼85 %). Despite the lowest HDS activities, FeMo with the cheapest Fe promoter, shows good DDS selectivity (∼70 %). Further study reveal NiMo has the most laminated morphology and highest stacking slabs, resulting in the highest HDS activity. Benefiting from the Co(Fe)-Mo-S structure and abundant sulfur vacancy, CoMo and FeMo showed great enhancement in the DDS selectivity. Moreover, the DDS selectivity of these designed catalysts were supported energetically by first principle calculations. This research will expand on the ability to improve the HDS activities and DDS selectivity by precisely engineering catalytic active sites to achieve significant synergistic effect in atomic scale.

Pd Nanoparticle Supported on N‐Doped Carbon Derived from Sodium Alginate/Melamine Blends as Efficient Heterogeneous Catalyst for Heck Reactions

AbstractN‐doped porous carbon shows great potential in the field of heterogenous supports due to its high porosity, large surface area, rich active sites, and strong chelation with catalytic active metals species. Herein, we successfully prepared a novel N‐doped porous carbon derived from sodium alginate/melamine blends (SAMNC) with different mass ratio through a simple carbonization and activation process. Hierarchical porous structure of the derived N‐doped carbon has been confirmed with the SEM, TEM, and N2 adsorption characterization. After Na2PdCl4 solution impregnation and further reduction process, Pd0 nanoparticles have been uniformly immobilized on the SAMNC support to produce novel Pd@SAMNC catalyst. The optimal Pd@SAMNC‐0.6 possesses a high N content (5.13%), Pd content (5.90%), large BET specific surface area of 1884.5 m2·g−1. Positron annihilation lifetime spectroscopy (PALS) investigation of the porous carbon materials provided the sub‐nano level microporous information proofs of Pd@SAMNC‐0.6 had the capability to provide more active sites for reactions than commercial Pd supported on activated carbon (Pd@AC). Pd@SAMNC‐0.6 catalyst showed superior catalytic efficiency in Heck coupling reaction between aromatic halides and alkenes and can be recycled for 17 runs without significant decrease in catalytic efficiency.

Immobilizing cobalt-iron bimetal on Al2O3 by electroless plating-calcination for peroxymonosulfate activation: Performance, mechanistic and practicality

Peroxymonosulfate (PMS) based advanced oxidation processes are promising technologies for emerging contaminants removal and exploring catalysts with high catalytic activity and low metal leaching for PMS activation gets a lot of attention. Herein, Co-Fe/Al2O3 was synthesized by electroless plating-calcination method. Characterizations indicated that Co and Fe were uniformly dispersed on the surface of Al2O3. Results demonstrated that Co-Fe/Al2O3-PMS system could achieve 100 % sulfamethoxazole (SMX) removal with kobs of 0.0552 min−1 under optimal conditions of [PMS] = 0.20 mM, [Co-Fe/Al2O3] = 50.0 mg/L, pH = 6.4. Compared with Co/Al2O3-PMS, Fe/Al2O3-PMS, Co-Fe/Al2O3 alone, and PMS alone, the developed Co-Fe/Al2O3-PMS system achieved a combination of high decontamination efficiency, efficient PMS utilization and insignificant Co leaching. The electrochemistry tests proved the electron transfer speed of Co-Fe/Al2O3 is much higher than that of Co/Al2O3 and Fe/Al2O3, suggesting the synergistic effect of Co and Fe to enhance catalytic activity. The catalytic mechanisms were proposed that both CoII and FeII could react with PMS to initiate activation with SO4•- formation as the major active species and the coexistence of Fe and Co on Al2O3 promoted the heterogeneous redox cycle of CoII/CoIII with CoII involving in PMS activation again. Furthermore, Cl− and H2PO4- facilitated SMX removal, while HCO3− and HA inhibited SMX removal. Co-Fe/Al2O3-PMS system could retain more than 80 % SMX removal within five cycles, indicating good stability and reusability of Co-Fe/Al2O3 for PMS activation. Aniline ring oxidation and isoxazole ring oxidation were proposed as dominant degradation pathways according to the detected intermediates of SMX degradation. This research was instructive to the development of PMS activation induced by supported bimetallic catalysts for wastewater treatment.

Double-layer heterostructure in situ grown from stainless steel substrate for overall water splitting

Developing free-standing electrode based on cost-effective industrial substrate materials is a promising way for efficient water splitting applications. The common stainless steel (S S) consisting of catalytic active transition metal components (e.g. Ni, Fe, etc.) has the potential to be an ideal substrate to prepare free-standing electrodes. In this work, a facile hydrothermal oxidization treatment was proposed to oxidize three types of SS substrates (i.e. 304, 316L and 310S) to prepare efficient free-standing electrodes for water electrolysis. Compared with the 316L and 310S, the relatively low content of Mo and Cr in 304 SS make it easier to be oxidized by alkaline hydrogen peroxide to produce a well-confined double layer heterostructured catalytic film with Fe-rich microcrystals at the top and Ni-rich nanocrystals at the bottom. Consequently, the as obtained 304-SSO27 sample exhibits low overpotentials of 136 mV and 285 mV at the current density of 10 mA·cm−2 towards hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively. Moreover, the bifunctional 304-SS-O27 electrode displays a low cell voltage of 1.67 V to realize overall water splitting at 10 mA·cm−2. These results provide a convincing demonstration of fabricating cost-effective and frees-standing electrodes via a facile one step hydrothermal oxidization for water splitting applications.

Role of Plasmonic Antenna in Hot Carrier-Driven Reactions on Bimetallic Nanostructures.

Noble metal nanostructures can efficiently harvest electromagnetic radiation, which, in turn, is used to generate localized surface plasmon resonances. Surface plasmons decay, producing hot carriers, that is, short-lived species that can trigger chemical reactions on metallic surfaces. However, noble metal nanostructures catalyze only a very small number of chemical reactions. This limitation can be overcome by coupling such nanostructures with catalytic-active metals. Although the role of such catalytically active metals in plasmon-driven catalysis is well-understood, the mechanistics of a noble metal antenna in such chemistry remains unclear. In this study, we utilize tip-enhanced Raman spectroscopy, an innovative nanoscale imaging technique, to investigate the rates and yields of plasmon-driven reactions on mono- and bimetallic gold- and silver-based nanostructures. We found that silver nanoplates (AgNPs) demonstrate a significantly higher yield of 4-nitrobenzenehtiol to p,p'-dimercaptoazobisbenzene (DMAB) reduction than gold nanoplates (AuNPs). We also observed substantially greater yields of DMAB on silver-platinum and silver-palladium nanoplates (Ag@PtNPs and Ag@PdNPs) compared to their gold analogues, Au@PtNPs and Au@PdNPs. Furthermore, Ag@PtNPs exhibited enhanced reactivity in 4-mercatophenylmethanol to 4-mercaptobenzoic acid oxidation compared to Au@PtNPs. These results showed that silver-based bimetallic nanostructures feature much greater reactivity compared to their gold-based analogues.

Single-atom Au-modified CeO2 catalyst: Structure and its catalytic performance in 2,4-diaminotoluene methoxycarbonylation reaction

In the reaction of dimethyl carbonate (DMC) and 2,4-diaminotoluene (TDA), Au/CeO2 exhibits higher selectivity than CeO2 for dimethyl toluene-2,4-dicarbamate (TDC). However, its catalytic activity drops after H2 reduction (denoted as Au/CeO2-R). The characterization results illustrate that Au exists as a single atom with the primary species as Auδ+ in Au/CeO2, forming CexAu1−xO2 structure similar to solid solution. Whereas for Au/CeO2-R catalyst, Au mainly exists as Au0, forming the Au-O-Ce structure on CeO2 surface. Significantly, the strong interaction between Au and CeO2 increases Ce3+ and oxygen vacancies content, as well as modulates their acidic property. However, the catalytic activity of Au/CeO2-R is found to be lower than Au/CeO2 as the species formed by DMC dissociation on its surface are not easily desorbed. Other transition metals supported on CeO2 are also prepared, wherein Pt/CeO2 and Pd/CeO2 exhibit good TDC selectivity. In the end, the electronegativity and catalytic activity of metals are correlated.

Yolk@shell nanoreactor with coordinately unsaturated metal sites on MOF surface inside polypyrrole capsule: Enhanced catalytic activity and lowered metal leaching in fenton-like reaction

Yolk@shell nanoreactor with coordinately unsaturated metal sites on MOF surface inside polypyrrole capsule: Enhanced catalytic activity and lowered metal leaching in fenton-like reaction

Surface-dependent CO oxidation over Au/ZnO nanopyramids and nanorods

The catalytic activity of metals is very sensitive to the surface orientation of supporting oxides but rather little is known about ZnO in this regard. Nanostructured support morphologies present an attractive research strategy there because they allow probing the catalytic impact of well-defined surfaces at ambient pressure. The predominant {101̅0} side planes of hexagonal ZnO nanorods (NR) are terminated with the same number of O and Zn atoms while both the (0001) basal and {101̅1̅} side planes of hexagonal ZnO nanopyramids (NPy) are Zn-terminated. STEM analyses reveal two Au//ZnO interfacial configurations for each system after deposition of ∼3 nm Au nanoparticles. CO oxidation proceeds 15 times faster over the Au/ZnO NR than the Au/ZnO NPy catalyst at room temperature. The difference in catalytic activity can be traced to facilitated CO activation at the interfacial sites of Au/ZnO NR while it is retarded due to co-adsorption of CO with CO32- at undercoordinated Zn2+ ions of the interfacial perimeter of Au/ZnO NPy according to CO DRIFTS analyses. These results demonstrate that the catalytic behavior of metal/ZnO systems are very sensitive to ZnO surface terminations and the associated metal//ZnO interface configurations.

The efficient degradation of high concentration phenol by Nitrogen-doped perovskite La2CuO4 via catalytic wet air oxidation: Experimental study and DFT calculation

Herein, N-doped perovskite La2CuO4 (LCO) (N-LCO(M)) was fabricated by sol–gel rapid calcination method using melamine (M) as N source/ligand, and applied for the catalytic wet air oxidation (CWAO) to degrade high-concentration phenol-containing simulated wastewater. The experimental results exhibited that N-LCO(M) illustrated enhanced phenol degradation efficiency. Thereinto, 87.9% COD degradation efficiency was achieved in simulated wastewater containing 8000 mg/L phenol, while for undoped LCO prepared with citric acid (CA) as ligand (LCO(CA)) was only 43.8%. The systematic characterizations and density functional theory (DFT) calculations were utilized to verify the above results. The results revealed that N doping favored the formation of more oxygen vacancies (*) and facilitated the charge transfer between Cu and O. More oxygen vacancies (*) reinforced the ability of N-LCO(M) to adsorb O2 to form reactive oxygen species (O*), and meanwhile, the charge transfer between Cu and O was manifested as the redox cycle of the catalytic active metal Cu2+/Cu1+. The redox cycle also promoted the formation of O2− and HO, making the more exhaustive degradation of phenol. This successfully proved that N doping was core to improving the activity and stability of N-LCO(M). Moreover, a possible mechanism of phenol degradation was proposed based on the experimental results and DFT calculations. Eventually, the toxicity of the intermediate products was further evaluated by quantitative structure–activity relationship (QSAR) analysis, showing the significantly reduced toxicity of the intermediate products. Overall, the proposed CWAO technique is a green and promising wastewater treatment method.

Experimental Study on Catalytic Action of Intrinsic Metals in Coal Spontaneous Combustion.

In order to study the effect of inherent metals in coal on spontaneous combustion, Hongmiao lignite and Hongqingliang long-flame coal were demineralized by hydrochloric acid, the raw coal and demineralized coal were characterized by Fourier transform infrared spectrometry, X-ray diffraction, and synchronous thermal analysis experiments, and the corresponding ash content was detected by inductively coupled plasma mass spectrometry. The results show that the effect of demineralization on the volatile matter of low-rank coal is small, and the change of crystallite structure is not significant. The removed parts are mainly water-soluble salts and soluble minerals, such as carbonates and metal ions, that are not tightly bound to the organic matter of coal structure. The removed metal elements are mainly alkali metals Na and K, alkaline earth metals Ca, Mg, Sr, and Ba, and transition metals Fe, Mn, Ti, and so forth. The temperatures corresponding to the end of weight loss, ignition, and maximum weight loss rates were elevated on the thermogravimetric curves of the demineralized coal samples. The heat absorbed by evaporation of water in coal and the heat released by oxidation and combustion of coal are decreased to different degrees, indicating that the spontaneous combustion tendency of coal after demineralization is reduced, and alkali metal, alkaline earth metals, and transition metals in coal have a catalytic effect on spontaneous combustion of coal. After adding the metal chelating agent ethylenediaminetetraacetic acid (EDTA), the apparent activation energy decreased by 33.08 and 2.42%, respectively. EDTA and the alkali metal, alkaline earth metal, or transition-metal ions formed a stable chelate in coal. The catalytic activity of metals is weakened or even lost, thereby inhibiting spontaneous combustion of coal, and verifying the catalytic effect of internal metals in coal on the spontaneous combustion of coal.

Reductive roasting of cathode powder of spent ternary lithium-ion battery by pyrolysis of invasive plant Crofton weed

Recycling spent lithium-ion batteries has received wide attention because the spent batteries are hazardous and contain high-grade and catalytic active heavy metals. Reductive roasting is an effective pretreatment method to recover valuable metals from the used batteries. In this paper, Crofton weed, which has been defined as an invasive plant in China, was suggested as a biomass pyrolysis additive for the reducing pretreatment of spent lithium-ion batteries powder (LiNi0.6Co0.2Mn0.2O2). The process can reduce carbon consumption for the spent battery recycling industry. Meanwhile, the Ni, Co, and other metals in the cathode powder could catalyze biomass pyrolysis, reducing the reaction's activation energy. The effects of temperature, biomass ratio, heating rate, and roasting retention time on the reduction were studied. TG-DSC, XRD, and SEM were used to characterize the experimental results, and the pyrolysis reduction mechanism was analyzed. Under the optimum roasting conditions: temperature 800 °C, biomass ratio 30%, heating rate 5 °C/min, without retention time, Li in the powder is converted into Li2CO3, and the high valence Ni, Co, Mn are reduced to low valence and easily soluble Ni, Co, and MnO, respectively. This method provided an alternative technology solution for both spent lithium-ion battery treatment and controlling invasive plants in China, namely Crofton weed.

Atomic Replacement of PtNi Nanoalloys within Zn-ZIF-8 for the Fabrication of a Multisite CO2 Reduction Electrocatalyst

Exploring the transformation/interconversion pathways of catalytic active metal species (single atoms, clusters, nanoparticles) on a support is crucial for the fabrication of high-efficiency catalysts, the investigation of how catalysts are deactivated, and the regeneration of spent catalysts. Sintering and redispersion represent the two main transformation modes for metal active components in heterogeneous catalysts. Herein, we established a novel solid-state atomic replacement transformation for metal catalysts, through which metal atoms exchanged between single atoms and nanoalloys to form a new set of nanoalloys and single atoms. Specifically, we found that the Ni of the PtNi nanoalloy and the Zn of the ZIF-8-derived Zn1 on nitrogen-doped carbon (Zn1-CN) experienced metal interchange to produce PtZn nanocrystals and Ni single atoms (Ni1-CN) at high temperature. The elemental migration and chemical bond evolution during the atomic replacement displayed a Ni and Zn mutual migration feature. Density functional theory calculations revealed that the atomic replacement was realized by endothermically stretching Zn from the CN support into the nanoalloy and exothermically trapping Ni with defects on the CN support. Owing to the synergistic effect of the PtZn nanocrystal and Ni1-CN, the obtained (PtZn)n/Ni1-CN multisite catalyst showed a lower energy barrier of CO2 protonation and CO desorption than that of the reference catalysts in the CO2 reduction reaction (CO2RR), resulting in a much enhanced CO2RR catalytic performance. This unique atomic replacement transformation was also applicable to other metal alloys such as PtPd.

Understanding the effect of mechanical strains on the catalytic activity of transition metals.

The effect of elastic strains on the catalytic activity for the hydrogen evolution reaction (HER) and the oxygen reduction reaction (ORR) was analyzed on thirteen late transition metals: eight (111) surfaces of fcc metals (Ni, Cu, Pd, Ag, Pt, Au, Rh, Ir) and five (0001) surfaces of hcp metals (Co, Zn, Cd, Ru, and Os). The corresponding adsorption energies for the different intermediate reactions up to strains dictated by the mechanical stability limits were previously obtained by means of density functional theory calculations. It was found that the elastic strains can be used to tune the catalytic activity of different metals by reducing the energy barrier of the rate limiting step and even to reach the cusp of the volcano plot. The largest changes in catalytic activity with strain for the HER were found in Pt, Au, and Ir while Co and Ni were very insensitive to this strategy. In the case of the ORR, the catalytic activity of Au could be enhanced by the application of tensile strains while that of Cu, Ni, Pt, Pd, Rh, Co, Ru, and Os was improved by the application of compressive strains. However, the catalytic activity of Ir was rather insensitive to mechanical deformations. Elastic strains were able to modify the rate limiting reaction in Au, Pt, Ag, and Os and it was possible to achieve the cusp of the volcano plot in these metals. Final, mechanical instabilities were attained at small strains in Zn and Cd, which did not lead to significant changes in the catalytic activity for the HER and the ORR. These results provide a framework to systematically investigate the application of elastic strains in the design of new catalysts.

Self‐Supporting Bimetallic Pt‐Ni Aerogel as Electrocatalyst for Ethanol Oxidation Reaction

AbstractThe fuel cell has attracted researchers’ attention owing to its advantages of being adjustable and controllable, wide application, high efficiency, and low energy, etc. However, the main cost of fuel cells still comes from catalysts at present. Platinum‐based catalysts are still the most widely used catalysts in both cathodic ORR reactions and anodic EOR reactions. For the anodic EOR process, combined with in‐situ improved self‐gelling and Galvanic Replacement methods, a kind of Pt−Ni aerogel composite with a three‐dimensional porous network structure was prepared. The obtained Pt−Ni bimetallic aerogel materials were characterized by using scanning electron microscopy (SEM), X‐ray photoelectron spectroscopy (XPS) and X‐ray diffraction (XRD). Furthermore, the electrocatalytic activity of the synthesized Pt−Ni aerogels for the oxidation of EtOH in KOH was measured. The prepared Pt−Ni aerogel has the characteristics of high conductivity and catalytic activity of metal itself and high specific surface area and porosity of aerogels. The peak current density of Pt−Ni aerogel was about two times of the Ni aerogel prepared under the same situation, and the ECSA of Pt−Ni aerogel was about twice that of Ni aerogel, indicating that the addition of Pt could increase the active site of Pt−Ni aerogel, which made the Pt−Ni aerogel composite material have excellent catalytic activity.

Ni nanodendrites prepared by a low-temperature process as electrocatalysts for hydrogen evolution reaction in alkaline solution

It is essential to explore high catalytic activity and stability inexpensive metal electrocatalysts for the hydrogen evolution reaction (HER) to achieve the hydrogen energy generation. Therefore, in this paper, we report a simple low-temperature method which is template-free and environmentally-friendly to fabricate the Ni nanodendrites (Ni NDs) manifesting the excellent HER catalytic performances. This method is a simple one-step reduction, and at 50 °C we obtain the Ni NDs50 that exhibit a low overpotential of 49 mV (10 mA cm−2) and a small Tafel slope of 32.70 mV dec−1 in 1.0 M KOH electrolyte. Besides, the Ni NDs50 exhibit the favorable stability for 22 h. The superior HER performance may be attributed to the exposure of more electrochemical surface areas due to the multiple branching dendrite structure. Hence, our research provides a simple method for large-scale preparing nickel-based electrocatalysts.

Highly Active and Stable a-Site Deficient La0.4Sr0.4Ti0.94Ni0.06O3-δ SOFC Anode Material with in-Situ Exsolved of Ni Nanoparticles

La-doped strontium titanates with a perovskite structure are promising candidates of the anode materials for solid oxide fuel cells (SOFCs) owing to their good chemical compatibility with other components and superior redox-stability. Among these La-doped SrTiO3 (LST), A-site deficient LST materials have attracted much interest due to their improved electrochemical characteristics. Recently, exsolution in A-site deficient LST has been intensively studied, because catalytic active and durable metal nanoparticles can be exsolved on the LST surface. In this study, we developed the A-site deficient Ni-doped La0.4Sr0.4TiO3 (LSTN)-Ce0.9Gd0.1O1.95 (GDC) composite anodes, and investigate their electrochemical performance and redox stability on La0.8Sr0.2Ga0.8Mg0.2O3-δ (LSGM) electrolyte-based SOFCs. The maximum power density(MPD) of LSTN44-GDC anode based cell was 0.698 mW cm-2 at 900℃ in wet H2 fuel (3% H2O). Also, during redox cyclic tests combined with long-term stability test, The LSTN44-GDC cell maintained its performance without any degradation. All these results demonstrate that the A-site deficient LSTN-GDC is a promising material for an efficient and stable SOFC anode.

Dual Metal-Loaded Porous Carbon Materials Derived from Silk Fibroin as Bifunctional Electrocatalysts for Hydrogen Evolution Reaction and Oxygen Evolution Reaction.

Developing electrocatalysts with high efficiency and long-term stability for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is significant to massively generate hydrogen energy by water splitting. In this work, cobalt and tungsten dual metal-loaded N-doped porous carbon electrocatalysts derived from silk fibroin were successfully prepared through facile carbonization and chemical activation by KCl and applied as efficient electrocatalysts for HER and OER. After chemical activation, the resulting catalysts present a unique hierarchical porous structure with micro-, meso-, and macropores, which is able to expose more implantation sites for catalytic active metals and will in turn promote the efficient diffusion of the electrolyte. The catalyst under the optimized condition (CoW@ACSF) has a specific area of 326.01 m2 g-1. The overpotential at a current density of 10 mA cm -2 of CoW@ACSF is 138.42 ± 10.39 mV toward HER and 492.05 ± 19.04 mV toward OER. Furthermore, the overpotential only increases 101.2 mV toward HER and 66.00 mV toward OER after the long-term stability test of chronopotentiometric test over 10 h, which confirms the excellent stability of the CoW@ACSF, owing to its unique carbon shell structure. This work gives an insight into the design and engineering of silk fibroin-derived carbon materials for electrocatalysis toward HER and OER.

The microbial community in a green turtle nesting beach in the Mediterranean: application of the Biolog EcoPlate approach for beach pollution.

This study aims to characterize the microbial community and its relationship with heavy metal pollution in the beaches of Sugözü, an important nesting site for the green turtle. Heavy metal concentrations of sand samples from subregions of Sugözü were determined using ICP-MS. The microbial community was analyzed using the Biolog® EcoPlate. The relationship between microbial catalytic activity and heavy metal levels were analyzed using canonical correspondence analysis. Levels of 27Al, 57Fe, 55Mn, and 52Cr were quite high (4332.34, 13,764.77, 590.98, and 48.21 mg/kg, respectively). The microbial community in subregions with high levels of metals was found to use carboxylic acid as a carbon source. Bioactivity, substrate utilization, diversity, and evenness values indicated negative correlations concentrations of 27Al, 56Fe, and 52Cr (-0.820, -0.508, and -0.560, respectively). It was also found that microbial diversity decreased in the subregions where heavy metal concentration increased. Embryonic deaths were found highest at early stage (0.1 to 0.2 eggs) and lowest at middle stage for whole study sites by inspecting a total 6408 eggs of 63 green turtle nests. The Biolog EcoPlate was firstly applied to determine pollution, and our findings clearly demonstrate the applicability and effectiveness of this method in assessing nesting beaches.