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As an emerging class of materials with distinctive physicochemical properties, metallenes are deemed as efficient catalysts for energy-related electrocatalytic reactions. Engineering the lattice strain, electronic structure, crystallinity, and even surface porosity of metallene provides a great opportunity to further enhance its catalytic performance. Herein, we rationally developed a reconstruction strategy of Pd metallenes at atomic scale to generate a series of nonmetallic atom-intercalated Pd metallenes (M-Pdene, M = H, N, C) with lattice expansion and S-doped Pd metallene (S-Pdene) with an amorphous structure. Catalytic performance evaluation demonstrated that N-Pdene exhibited the highest mass activities of 7.96 A mg

Single-atom catalysts (SACs) have aroused tremendous interest over the past decade, particularly in the community of energy and environment-related electrocatalysis. A rapidly growing number of recent publications have recognized it as a promising candidate with maximum atomic utilization, distinct activity, and selectivity in comparison to bulk catalysts and nanocatalysts. However, the complexity of localized coordination environments and the dispersion of isolated sites lead to significant difficulties when it comes to gaining insight into the intrinsic behavior of electrocatalytic reactions. Furthermore, the low metal loadings of most SACs make conventional ensemble measurements less likely to be accurate on the subnanoscale. Thus, it remains challenging to probe the activity and properties of individual atomic sites by available commercial instruments and analytical methods. In spite of this, continuing efforts have lately focused on the development of advanced measurement methodologies, which are very useful to the fundamental understanding of SACs. There have recently been a number of in situ/operando techniques applied to SACs, such as electron microscopy, spectroscopy, and other analysis methods, which support relevant functions to identify the active sites and reaction intermediates and to investigate the dynamic behavior of localized structures of the catalytic sites.This Account aims to present recent electrochemical probing techniques which can be used to identify single-atomic catalytic sites within solid supports. First, we describe the basic principles of molecular probe methods for the study and analysis of electrocatalytic site behavior. In particular, the in situ probing technique enabled by surface interrogation scanning electrochemical microscopy (SI-SECM) can measure the active site density and kinetic rate with high resolution. An alternative electrochemical probing technique is further demonstrated on the basis of single-entity electrochemistry, which allows the unique electrochemical imaging of the size and catalytic rate of single atoms, molecules, and clusters. The merits and limitations of different electrochemical techniques are then discussed, along with perspectives for future prospects. Apart from this, we further showcase the powerful capability of emerging electrochemical probing techniques for determining significant effects and properties of SACs for various electrocatalytic reactions, including oxygen reduction and evolution, hydrogen evolution, and nitrate reduction. Overall, electrochemical techniques with atomic resolution have greatly increased opportunities for observing, measuring, and understanding the surface and interface chemistry during energy conversion. In the future, it is anticipated that the development of electrochemical probing techniques will be advanced with innovative perspectives on the behavior and features of SACs. We hope that this Account can contribute in several ways to promoting the fundamental knowledge and technical progress of emerging electrochemical measurements for studying SACs.

We report a wire-shaped bifunctional oxygen photoelectrode by integrating Li-doped TiO2 nanotubes and Pt nanoclusters.

Regulating the site density of single-atom catalysts (SACs) promotes the potential to remarkably improve the performance of electrocatalysis, such as the oxygen reduction reaction (ORR). However, the catalytic behaviour governed by individual and interacting sites is particularly elusive and has yet to be understood. Here we demonstrate the origin of the enhancement of the ORR activity of isolated Fe–N4 SACs over inter-site distances down to the subnanometre level. Strong interactions between adjacent Fe–N4 moieties alter the electronic structure when the inter-site distance is less than about 1.2 nm, resulting in increased intrinsic ORR activity. The marked improvement in site performance continues until neighbouring Fe atoms approach as close as about 0.7 nm, below which the intrinsic activity is slightly diminished. The present study highlights the significance of identifying the fundamental mechanism of the inter-site distance effect in Fe–N4 catalysts for the ORR, which may promote the full potential of densely populated SACs. Single-atom catalysts containing Fe–N4 active sites have been developed as effective noble-metal-free catalysts for the oxygen reduction reaction. Here the authors untangle the effects of active site density and cooperativity between neighbouring single-atom sites at well-defined distances.

The necessity to pursue sustainable ammonia (NH3) production with economic and environment-friendly technologies is growing with the global development aim of future fertilizer and renewable energy industries. Electrosynthesis of ammonia from nitrate reduction is encouraging for both environmental nitrogen pollution management and artificial nutrient recycling. However, it is fundamentally difficult to regulate the reaction pathways for efficient and selective ammonia production over competing reactions, e.g., the hydrogen evolution reaction, particularly under aqueous conditions. Enlightened by the unique and tunable local electronic structures, an iron-based single-atom catalyst is reported in this contribution. We demonstrate a polymer-hydrogel strategy for preparing nitrogen-coordinated Fe sites with uniform atomic dispersion on carbon. The catalyst exhibits a maximum NH3 yield rate of 2.75 mgNH3 h−1 cm−2 (ca. 30 molNH3 h−1 gFe−1) with nearly 100% faradaic efficiency. Furthermore, the catalytically active individual Fe site in the isolated atom state displays a twelve times higher turnover frequency than that in metallic Fe nanoparticles. Experimental evidence suggests that the single-site iron would experience a nitrate-preoccupied transition center, which prohibits water adsorption as the competitive reaction that generally exists for bulk catalysts. Theoretical insights into the localized structure further assist in better understanding and support of the high selectivity for NH3 achieved by the Fe single-atom catalyst.

Over the past decades, flexible and wearable energy storage devices have received tremendous interest due to the development of smart electronic products, such as Apple Watch, Google Glass, and sport wristbands. Fiber-shaped electrochemical energy storage devices (FEESDs) derived from fibrous electrodes are standing out as a result of the excellent flexibility and breathability compared with the planar counterparts. Textiles and fabrics can be simply achieved by spinning and weaving FEESDs, which perfectly match with an arbitrary uneven and mobile surface, revealing enormous potentialities in wearable electronics. Combining mechanical features with the electrically conductive properties and biocompatibility, conductive polymers (CPs) have emerged as a promising candidate for smart textile products including medical textiles, protective clothing, touch screen displays, and flexible fabric power supplies. In this context, this review summarizes the material design of CPs for fibrous electrodes and provides a critical discussion on their applications in flexible energy storage devices. Meanwhile, basic principles are briefly presented, including the conduction mechanism of conductive polymers, fibrous electrode design, and the evaluation of the electrochemical/mechanical performance for fibrous devices. Last, possibilities and challenges for the development of CP derived FEESDs are outlined as well.

We report a wire-shaped bifunctional oxygen photoelectrode by integrating Li-doped TiO

Surface interrogation scanning electrochemical microscopy (SI-SECM) of two electrodeposited manganese-based electrocatalysts, amorphous MnOx and perovskite CaMnO3 , was used to investigate the manganese oxidation state relating to the oxygen evolution reaction (OER) under neutral conditions. The results indicate the amounts of MnIII and MnIV species in MnOx and CaMnO3 depend on potential. A MnV species was identified in both structures during the OER. Time-delay titration of MnV further revealed that MnOx produced two types of active sites with different OER reaction rates: k'fast (MnOx )=1.21 s-1 and k'slow (MnOx )=0.24 s-1 . In contrast, CaMnO3 perovskites in which the MnV species formed at a less positive potential than that in MnOx , displayed only one kinetic behavior with a faster reaction rate of 1.72 s-1 .

A surface-strained and geometry-optimized TiO2 nanoreactor enhances the performance of electrocatalytic nitrogen fixation. The nanotubular confinement allows spatial regulation of the mass transport of nitrogen during the NRR process and offers an enlarged surface area, thus boosting the ammonia production with high selectivity. Both experimental and theoretical evidence support strained Ti3+ sites, demonstrating a more favorable pathway for the N2 activation and selective NH3 production with a faster kinetic rate than the pristine TiO2 . The TiO2 -based nanoreactor with surface and bulk structure tailoring delivered an NH3 yield rate up to 5.50 μg h-1 cm-2 (16.67 μg h-1 mgcat-1 ) and high faradaic efficiency of 26 % under ambient aqueous conditions. Our findings highlight the concept of lattice strain and geometry modified nanoreactors, which will have broad implications in the renewable energy catalysis and electrosynthesis of valuable products.

Single-atom catalysis has emerged as a cutting-edge field in heterogeneous catalysis. Considerable efforts have been devoted to developing versatile methodologies for synthesizing single-atom catalysts, however, the main thrust in this field is to fundamentally understand the intricacies of a catalyst and their performance on a specific reaction by complimenting different techniques. Here we demonstrate a supramolecular hydrogel strategy to effectively isolate copper atoms on interconnected carbon fibers as efficient electrocatalysts for the alkaline oxygen reduction reaction (ORR). The Cu–N2 coordination state and the atomic dispersion were confirmed by X-ray absorption spectroscopy and aberration-corrected scanning transmission electron microscopy. Additionally, the atom utilization (ηatom), which is the ratio between Cu(I) sites participating in the catalysis and the total Cu(I) sites available, has been investigated via surface-interrogation scanning electrochemical microscopy (SI-SECM) technique. The over 90% atom utilization of the synthesized Cu SACs is very close to the theoretical value (100%) for SACs, implying the proposed supramolecular approach can enable the ultrahigh exposure of Cu sites. The in situ time-resolved titration of SI-SECM and first-principal calculations further support the remarkable ORR activity on isolated Cu–N2 sites.

Ammonia (NH

Aqueous Ni/Fe alkaline batteries with features of low cost and high safety show great potential for application in portable and wearable electronics. However, the poor kinetics of the Fe-based anode greatly limits the large-scale applications of Ni/Fe batteries. Herein, we report an interconnected 3D conductive network with carbon-coated nanostructured iron/iron oxide (3D-Fe/Fe2O3@C) as an efficient anode for a flexible Ni/Fe battery. A hydrogel precursor is used to molecularly link and confine Fe3+ to spatial networks, resulting in a uniform dispersion of Fe/Fe2O3-heterostructured nanoparticles. Theoretical investigations reveal regulated potential loss and improved delocalized carrier density as a result of carbon coating and the mixed metal/metal oxide structure. In addition to these merits, due to the regulated wettability and electroactive surface areas, the 3D-Fe/Fe2O3@C anode with a high mass loading delivers an extraordinary areal capacity of 3.07 mA h cm-2, as well as the boosted rate capability and Coulombic efficiency. When coupled with the NiCo2O4 cathode, the flexible quasi-solid-state Ni/Fe battery exhibits an admirable energy density of 15.53 mW h cm-3 and a maximum power density of 761.91 W h cm-3. The good stability after 20,000 cycles and severe mechanical deformations of the as-fabricated Ni/Fe battery imply it as a promising flexible energy storage device for practical applications.

Depression will have a severe impact on social harmony and family happiness. Aiming at users Weibo users, this paper explores the use of deep learning methods. Based on the sentence sentiment analysis task, we propose a depression tendency detection model for Weibo users based on Bi-LSTM. Firstly, Use the Skip-Gram model in Word2Vec to vectorize the text. Adopt Bi-LSTM neural network layer. Through the bidirectional transmission, semantic dependence of capture context, mining the content characteristics of Weibo text. Finally, the text sentiment category is classified through the fully connected layer. The experimental results show that this method can effectively detect the depression tendency for Weibo users.

The design of efficient and low-cost electrocatalysts for both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) remains a significant challenge for the hydrogen production. Herein, CuO nanowires encapsulated by Ni and NiFe hydroxides (CuO@Ni/NiFe hydroxides) in-situ grown on the surface of Cu plate were fabricated via chemical oxidation-calcination process and room-temperature interfacial Galvanic reaction, which were applied to the efficient overall water splitting. Thanks to the improved specific surface area and the conductivity, the optimized core-shell CuO@Ni/NiFe hydroxides nanowire array exhibit impressive OER performance as well as HER activity in 1 M KOH which delivers a current density of 10 mA cm −2 at an overpotential of 230 mV for OER and 125 mV for HER. Significantly, core-shell CuO@Ni/NiFe hydroxides used as bifunctional catalysts for an overall water splitting can achieve a low onset potential of ∼1.50 V and a relatively high specific current density of 40 mA cm −2 at ∼1.73 V. This feasible strategy provides an accumulative opportunity for fabricating low-cost, effective bifunctional catalysts for overall water splitting.

Great efforts have been devoted to unveiling structural contributions of transition heterometallic materials to enhanced catalysis, while effective in situ approaches are still urgently demanded to...

Asymmetric supercapacitors (ASCs) as a promising candidate to complement batteries, have been studied for decades due to the relatively high power density. The energy storage of ASCs is significantly affected by the well-designed electrode material and delicate charge balance of electrodes. With the hope to design better supercapacitor devices, we firstly synthesize C-NiO/NiCo2O4 nanocomposites with the modified nanowire structure and a small amount of carbon, effectively boosting the specific capacitance and cyclic-stability. In addition, a multi-electrode system is developed to investigate match degrees of C-NiO/NiCo2O4//AC ACSs, and the inter-restricted behavior of positive and negative electrodes. By this real-time electrochemical method, the potential contributions of electrodes in ASCs are further revealed during charge/discharge process. Therefore, ASC device with optimal match degree delivers areal capacitance up to 3482 mF cm−2, and the maximum energy and power density of 42.69 mWh cm−3 and 1.66 W cm−3. Importantly, this work throws light on the fundamental study for supercapacitors in terms of materials design and charge match degrees.

Objective B7-H3 is a member of the B7 family of immune checkpoint molecule. Although B7-H3 has been shown to regulate T cell-mediated peripheral immune response, whether it also correlated with NK cell exhaustion in ovarian cancer remains unclear. The purpose of this study was to explore the mechanism of B7-H3 regulating NK-cell proliferation and function. Material and methods To investigate the relationship between B7-H3 expression and the NK-cell function in ovarian cancer, human ovarian tumor tissues and cell lines were first examined the protein and mRNA expression of B7-H3 by quantitative real-time PCR (qRT-PCR), Immunohistochemistry and Western-blot assays. Then we established B7-H3 knockout cell lines and measured the cytotoxicity of NK cells on these cells by LDH release assay and Flow Cytometry. In addition, we analyzed B7-H3 in the regulation of glycolysis and glycolysis-related proteins by Glycolysis Stress Test, Glucose Consumption Assay and Western-blot. Moreover, luciferase reporter assay was used to confirm the directly regulation of miR-29c to B7-H3. Finally, we carried out in vivo experiments. Results We observed that tumor-expressed B7-H3 inhibits NK-cell function in vitro and in vivo, and is associated with glycolysis of ovarian cancer cell. Therapeutically, B7-H3 blockade prolonged the survival of SKOV3 tumor-bearing mice. In addition, miR-29c improved the anti-tumor efficacy of NK-cell by directly targeting B7-H3 in vitro were observed, but not in vivo. Conclusion Our results demonstrate that miR-29c downregulates B7-H3 to inhibit NK-cell exhaustion and associated with glycolysis, which suggest that NK cells may be a new target of anti-B7-H3 therapy in ovarian cancer patients.

Seismic monitoring of injected CO2 plumes in fractured storage reservoirs relies on accurate knowledge of the physical mechansims governing elastic wave propagation, as described by appropriate, validated rock physics models. We measured laboratory ultrasonic velocity and attenuation of P‐ and S‐waves, and electrical resistivity, of a synthetic fractured sandstone with obliquely aligned (penny‐shaped) fractures, undergoing a brine‐CO2 flow‐through test at simulated reservoir pressure and temperature. Our results show systematic differences in the dependence of velocity and attenuation on fluid saturation between imbibition and drainage episodes, which we attribute to uniform and patchy fluid distributions, respectively, and the relative permeability of CO2 and brine in the rock. This behaviour is consistent with predictions from a multi‐fluid rock physics model, facilitating the identification of the dispersive mechanisms associated with wave induced fluid flow in fractured systems at seismic scales.

We report an electrodeposition protocol for preparing isolated cobalt oxide single molecules (Co(1)O(x)) and clusters (Co(n)O(y)) on a carbon fiber nanoelectrode. The as-prepared deposits are able to produce well-defined steady-state voltammograms for the oxygen evolution reaction (OER) in alkaline media, where the equivalent radius (r(d)) is estimated by the limiting current of hydroxide oxidation in accordance with the electrocatalytic amplification model. The size of isolated clusters obtained from the femtomolar Co(2+) solution through an atom-by-atom technique can reach as small as 0.21 nm (r(d)) which is approximately the length of Co–O bond in cobalt oxide. Therefore, the deposit was close to that of a Co(1)O(x) single molecule with only one cobalt ion, the minimum unit of the cobalt-based oxygen-evolving catalyst. Additionally, the size-dependent catalysis of the OER on Co(n)O(y) deposits shows a faster relative rate on the smaller cluster in terms of the potential at a given current density, implying the single molecular catalyst shows a superior OER activity.

MotivationProtein and peptide drugs, after decades of development have grown into a major drug class of the marketplace. Target identification and validation is crucial for their discovery, and bioinformatics estimation of candidate targets based on characteristics of successful target proteins will help improve efficiency and success rate of target selection. However, owing to the development history of the pharmaceutical industry, previous systematic exploration of target space mainly focused on traditional small-molecule drugs, whereas that for protein and peptide drugs is blank. Here we systematically explored target spaces in the human genome specially for protein and peptide drugs.ResultsWe found that compared with other proteins, targets of both successful protein and peptide drugs have their own characteristics in many aspects and are also significantly different from those of traditional small-molecule drugs. Further based on these features, we developed effective genome-wide target estimation models respectively for protein and peptide drugs.

Endometriosis (EMs) is defined as the presence of tissue which somewhat resembles endometrial glands and stroma outside the uterus, and elicits fibrosis. Fibrosis is the main factor resulting in pain and infertility, while the aetiology of endometrial fibrosis is unknown. There is strong evidence from numerous experiments showing that connective tissue growth factor (CCN2) plays a central role in fibrogenesis. Exosomal miR-214-3p can regulate the expression of CCN2 through binding to complementary sites in the 3' untranslated region. This study aimed to explore the role of exosomal miR-214-3p in endometriosis fibrosis and the relationship between CCN2 and miR-214-3p in endometriosis fibrosis. Our results demonstrated that miR-214-3p was significantly down-regulated and CCN2 was up-regulated in EMs ectopic lesion and stromal cells compared with EMs eutopic and endometrium of patients without endometriosis. Exosomal miR-214-3p can inhibit fibrosis in EMs through targeting CCN2. The results were explored and verified in vitro and in vivo, respectively. Cell co-culture was used to explore the contributions of exosomes to intercellular information transmission of miR-214-3p. The results showed that exosomes play a pivotal role in the transportation of miR-214-3p between cells. Furthermore, level of exosomal miR-214-3p in endometriosis patients' serum was lower than that in patients without endometriosis. In conclusion, exosomal miR-214-3p can inhibit fibrosis in EMs by targeting CCN2. MiR-214-3p may be considered as a bio-marker and has a potential therapeutic effect in EMs.

Seismic anisotropy has widely been used for the characterization of fractures in a reservoir. Recent work has demonstrated the effect of seismic dispersion on producing a frequency-dependent reflection coefficient, which can be important in fracture characterization since large fractures often lead to frequency-dependent anisotropy. In this paper, we examine the impact of anisotropic dispersion on P-wave reflections based on an HTI sand model encased within VTI shale. Although VTI in the overburden does not lead to azimuthal anisotropy, its effect on angle dependence could significantly affect the azimuthal AVO responses at far offsets. We show a modest effect on the amplitude and large effect on the phase, the latter of which could even be mistaken for azimuthal velocity variations. We present a Bayesian inversion based on a forward modelling technique aimed at recovering water saturation, fracture density and fracture length of a HTI sand. Our results show potential of using seismic dispersion in azimuthal AVO analysis to discriminate large-scale fractures from micro-scale cracks.

The poor conductivity and sluggish kinetics of nickel/iron oxide in the electrochemical process significantly limits the efficient energy storage of conventional alkaline Ni/Fe battery. Herein, we report a defect engineering based superficially doping strategy to prepare manganese doped NiO and Fe2O3 nanostructured fibrous electrodes with exceptional electrochemical properties. Extensive experimental and theoretical investigations have been carried out, which indicates defect-rich shells are formed on the surface of the original metal oxide structures with improved carrier density, thus effectively boosting the capacity, rate performance and durability of electrodes. Finally, a flexible Ni/Fe fiber-shaped battery with gelled electrolyte is assembled, delivering an impressive volumetric energy density of 61.0 mW h cm−3 and power density of 48.4 W cm−3 with robust cycling stability of 91.2% capacity retention after 30,000 cycles, which is promising as the next-generation lightweight, wearable and rechargeable energy device.

Ni/Zn batteries show the high theoretical capacity (370–619 mAh g -1 ) and output voltage (~ 1.8 V) in aqueous solution, while they are limited by the poor rate capability and cycling stability due to the shape change, dendrite formation and corrosion of anodic zinc electrode. Besides, the continued miniaturization of portable electronics requires the construction of fiber-shaped energy storage devices due to its exceptional flexibility, machinability, lightweight and large volumetric energy (power) density. Herein, we propose a three-dimensional nanotube-array supported fiber-shaped anode (Li-RTiO 2 ) of Ni/Zn battery with the ability to accommodate zinc deposition as nanoparticles instead of bulk dendritic crystals, greatly facilitating the anodic reaction rate of the Zn/ZnO 2 2- couple. Thus the flexible fibrous battery reveals the impressive maximum volumetric energy density of 0.034 Wh cm -3 , power density of 17.5 W cm -3 , high electric energy efficiency of 91% and about 5% capacity loss after 20,000 cycles.

Amplitude-versus-offset (AVO) inversion always plays an important role in reservoir fluid identification, which allows the estimation of various rock and fluid properties from prestack seismic data. In this paper, we propose a new method for discrimination of hydrocarbon accumulation that combines frequency-dependent AVO inversion scheme and variational mode decomposition (VMD). VMD is a recently developed algorithm for adaptive signal decomposition that is able to nonrecursively decompose a multicomponent signal into a number of quasi-orthogonal intrinsic mode functions and avoid mode mixing effectively. VMD is superior to other state-of-the-art approaches in obtaining high-resolution and high-fidelity local time–frequency depiction performance. Two synthetic signals are employed to illustrate that VMD achieves higher temporal and frequency resolution than the conventional continuous wavelet transform (CWT) decomposition. Other synthetic examples, elastic and dispersive, are utilized to demonstrate that the proposed method is more reliable for the detection of hydrocarbon saturation and a comparison is made with the CWT-based inverted results. Application on field data has further shown that the proposed approach has the potential in identifying the reservoir related to hydrocarbon.

Electrochemical water splitting involves two half-cell reactions, that is oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), and the overall reaction is severely restricted by the OER sluggish kinetics. Hence, to design and develop superior active and low-cost OER electrocatalyst is of significant necessary. In this study, the bimetallic cobalt-iron phosphates nanosheets (denoted as Co-Fe-P-O) with high activity toward OER has been constructed via a rapid microwave-assisted process using sodium hypophosphite and ethylene glycol as the phosphorus source and reaction solvent, respectively. Due to the structural feature of a larger electrochemical active surface area, the catalyst exerts a small overpotential of 267 mV at a current density of 10 mA cm−2 and a low Tafel slope of 30 mV dec−1 in 1.0 M KOH solution. The as-prepared catalyst also shows an outstanding stability with a current density retention of 94% at a constant water oxidation for almost 10 h. All of the results suggest that the performance of the catalyst prepared in our work is better than the state-of-the-art commercial RuO2 and even can rival most of transition metal-based material.

As potential catalytic materials for the oxygen evolution reaction, abundant and eco-friendly iron-based materials are often limited by inferior electrical conductivity. Herein, we propose a cost-effective and facile strategy to prepare a Fe/C heterostructured composite (Fe/Fe3C–F@CNT) via ultra-fast pyrolysis of ferrocene based on the induction and microwave thermal effect of multiwalled carbon nanotubes (CNTs). Fe/Fe3C–F@CNT exhibits a novel heterostructure where carbon-encapsulated Fe/Fe3C nanoparticles are uniformly distributed on the surface of CNTs and small iron-based nano-clusters exist on the surface of carbon layer, thus improving the electrical conductivity and dispersion of active sites. Fe/Fe3C–F@CNT shows superior OER catalytic performance, which is better than that of many Co- and Ni-based catalysts and even superior to that of RuO2. Furthermore, the catalytic performance further improved by loading Fe/Fe3C–F@CNT on the commercial foam iron. The resultant composite required a low overpotential (286 mV) to reach the current density of 10 mA cm−2. The durable catalytic stability, exhibiting no significant degradation at 100 mA cm−2 after 320 h, makes Fe/Fe3C–F@CNT a promising efficient, low-cost and environmentally-friendly OER catalyst for application in water electrolysis and metal–air batteries. More importantly, this study greatly shortens the preparation time required to fabricate uniform Fe/C heterostructures. This study brings a new inspiration for fabricating various materials for application as green energy sources.

Ammonia has been regarded as an irreplaceable chemical for human life as its essential role in fertilizers, pharmaceuticals, and renewable energy. At present, ammonia is industrially derived from fossil fuels with the well-known Haber–Bosch process, which is energy-consuming as well as environmentally unfriendly. The electrosynthesis approach is currently under intensive research as a future basis for producing ammonia from renewable sources. This review presents in-depth mechanistic studies and recent progress in single-atom electrocatalysts as an emerging platform for ammonia synthesis from the electroreduction of molecular dinitrogen and nitrogen oxides, particularly nitrate anion. In the conclusions and outlook, our discussion explores some key perspectives of future developments in the field. It is believed that ammonia electrosynthesis from a variety of nitrogen species via renewable electricity is of a great prospect to offer environmental, energy, and sustainability benefits.

Zn-air battery, as an ideal energy conversion and storage device, is always limited by the expensive and less-than-ideal air electrode materials. The coupling of outstanding oxygen evolution reaction (OER) active sites (oxides derived from Co-Fe nitrides) and superior oxygen reduction reaction (ORR) active centers (metal-N-C and graphitic N) to acquire high-performance and low-cost catalysts is an ideal solution. Herein, we have successfully combined cobalt-iron bimetallic nitrides with N-doped multi-walled carbon nanotubes (Co-Fe-N@MWCNT) as a robust bifunctional material. Benefiting from the synergistic effect between Co, Fe and MWCNTs, Co-Fe-N@MWCNT not only possesses large electrochemically active surface area and effective transport path, but also realizes the integration of superior OER and ORR active sites. Only a low overpotential (290 mV) is needed to achieve a current density of 10 mA cm -2 for OER and the ORR catalytic activity is close to that of the commercial Pt/C. Additionally, Co-Fe-N@MWCNT as an ideal air electrode material can also be applied in Zn-air battery, which exhibits low voltage drop and favorable stability. The voltage gap has a slight change (about 0.03 V) even after 100 cycles of galvanostatic charge-discharge. More importantly, the synthetic strategy in our work may facilitate the design of more high-efficient bifunctional catalysts in various domains.

We develop a 3D nanowire-supported Cu network through electrodepositing an active metal layer (NiZn alloy and Fe) to grow NiZn–phytate and Fe–phytate nanostructures as the anode and cathode, respectively, of a flexible energy storage device. Besides, this work aims to discuss the reasons behind the energy storage mechanism via the Dunn’s method and the results reveal that our device exhibits both surface capacitive effects and diffusion-controlled insertion processes, suggesting that it combines the properties of batteries and capacitors during the charge storage process. Therefore, the fabricated Ni/Fe cell can deliver high energy (185.33 W h kg−1) and power densities (15.93 kW kg−1), surpassing many recently reported appliances, such as commercial Li thin-film batteries, supercapacitors and other Ni/Fe batteries. Additionally, the Ni/Fe full cell also shows desirable long-term stability (about 86% retention after 8000 cycles at 20.83 A g−1). Moreover, the Ni/Fe cell can maintain its electrochemical performance under various bending states as well as being a promising power supply for wearable smart products. These features demonstrate that our proposed cell has potential for practical application as a next generation energy storage device. Importantly, the green and facile approach involving the application of phytic acid, which is abundant in living organisms, can be used to fabricate electrodes in our future research.

In this paper, the biaxial loading path effects on the mode I plane strain elastic-plastic crack-tip stress fields are investigated computationally. First, three different loading sequences including one proportional loading and two non-proportional loading paths are applied to the modified boundary layer (MBL) model under small-scale yielding conditions. For the same external displacement field applied at the outer boundary of the MBL model, the mode I K field and T-stress field combined as the different loading paths are applied to investigate the influence of the nonproportional loading. The results show that for either the compressive or tensile T -stress, the loading path which applied K field first followed by T-stress field generates the lower crack-tip constraint comparing to proportional loading. There is only minor difference between the results from proportional loading path and that with the T-stress field applied first following by K field. Next, two finite width specimens under non-proportional biaxial loading conditions that generate the same three loading paths are analyzed. Similar crack tip characteristics are observed in these specimens as these obtained from the MBL model, and it is demonstrated that the near-tip behavior in specimens can be predicted accurately using the results from MBL models. The present results show that it is very important to include the load sequence effects in elastic-plastic fracture analysis when dealing with nonproportional loading conditions.

Electrochemical water splitting in an alkaline electrolyte for large-scale hydrogen production is currently a hot research topic. However, developing high-performance and durable oxygen-evolving electrocatalysts is an ongoing challenge. In this work we prepared Ni-phytate thin films with a bubble-like structure on Ni-foam through an in situ growth process. The resulting material can be used as an oxygen-evolving electrode in basic media without requiring the use of a conductive binder. The Ni-phytate electrode has high catalytic activity (ηj=10mAcm−2=280mV) and good stability (the current activity remained 95% after 5 h) towards OER. This is an effective approach to simplifying the large-scale preparation of catalysts for water-splitting applications. Keywords: Oxygen evolution reaction, In situ formation, Ni-phytate, Sodium phytate, Water oxidation

An interconnected catalyst architecture has been in situ fabricated on Ni foam through facile electrochemical corrosion in sodium phytate containing Co and Fe metal ions. The introduction of Co and Fe in the N-phy system enables the phytate ions to link more active metal ions and then creates abundant catalytic sites to enhance the water oxidation performance and simultaneously to improve the overall water splitting activity. As a result, this self-supported C6FN-phy electrode delivers a high current density of 200 mA cm−2 at an overpotential of 285 mV for oxygen production and at 327 mV for hydrogen evolution in 1 M KOH, surpassing most catalysts recently reported. Besides, the electrocatalytic activity can be maintained for at least 45 h with a subtle potential increase, illustrating the versatile and practical application in industry. What's more, we achieve a current density of 100 mA cm−2 at 1.91 V by using C6FN-phy as the cathode and anode for overall water splitting, which is well comparable to the integrated performance of Pt/C and RuO2. Most importantly, multiple alternating chronopotentiometric tests of C6FN-phy as both the OER and the HER catalyst also verify the high availability and robust durability of the electrode as a true bifunctional electrocatalyst.