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As an efficient, controllable, economical, green and low-carbon soil remediation technology, bio-slurry remediation technology can be used for bioremediation of various organic contaminated soils.

As the final stage of the mixing process, the final mixing has a profound impact on the properties of rubber compounds. The influence of the process parameters of a continuous final mixer on the properties of carbon black/rubber composites is studied. It is found that there are two factors affecting the performance of the composite: the rotating speed of the dual rotors and the temperature of the continuous final mixer. When the temperature is unchanged, the extruding temperature of the final-mixing rubber compound increases with increasing rotating speed, and the Mooney viscosity, T10, T90 and rolling resistance gradually decrease. The Payne effect decreases first and then increases, and the overall trend gradually decreases. When the rotating speed is constant, as the temperature of the continuous final mixer rises, the extruding temperature also rises, and the temperature difference between feeding and extruding increases. Mooney viscosity and tensile strength increase. The Payne effect is more significant. T10, T90 and rolling resistance gradually decrease. The M300 of a vulcanized sample shows the following laws: When the control temperature is low, the influence of rotational speed is small, the fluctuation range is small, and has a steady rising trend; however, when the temperature is higher, M300 fluctuates greatly under the influence of rotational speed. The optimal process parameters of the rubber continuous final mixer are determined: the double rotor speed is 30RPM, and the temperature control temperature is 60–70 °C.

New nanostructures often reflect new and exciting properties. Here, we present an two-dimensional, hitherto unreported PdO square network with lateral dimensions up to hundreds of nanometers growing on reduced graphene oxide (rGO), forming a hybrid nanofilm. An intermediate state of dissolved Pd(0) in the bacterium S. oneidensis MR-1 is pivotal in the biosynthesis and inspires an abiotic synthesis. The PdO network shows a lattice spacing of 0.5 nm and a thickness of 1.8 nm on both sides of an rGO layer and is proposed to be cubic or tetragonal crystal, as confirmed by structural simulations. A 2D silver oxide analog with a similar structure is also obtained using an analogous abiotic synthesis. Our study thus opens a simple route to a whole new class of 2D metal oxides on rGO as promising candidates for graphene superlattices with unexplored properties and potential applications for example in electronics, sensing, and energy conversion.

Prussian blue analogues (PBAs) with inherent ordered structures and abundant metal ion sites are widely explored as precursors for various electrochemical applications, including oxygen evolution reaction (OER). Using a range of characterization techniques including Fourier-transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS), this work discloses the process of replacement of K + by NH 4 + in the interstitial spaces of the CoFe PBA by a hot aqueous urea solution, which influences the transformation of PBAs under further heat treatment and the OER performance of the derivatives. After heat treatment at 400 °C under Ar flow, high-resolution transmission electron microscopy (HRTEM) images reveal that CoFe alloy nanoparticles grew on the crystalline cubes of CoFe PBA with K +, while CoFe PBA cubes with NH 4 + become amorphous. Besides, the derivative of CoFe PBA with NH 4 + (Ar-U-CoFe PBA) performs better than the derivative of CoFe PBA with K + (Ar-CoFe PBA) in OER, registering a lower overpotential of 305 mV at 10 mA cm −2, a smaller Tafel slope of 36.1 mV dec −1, and better stability over a testing course of 20 h in 1.0 M KOH. A single-cell alkaline electrolyzer, using Ar-U-CoFe PBA and Pt/C for the anodic and cathodic catalyst, respectively, requires an initial cell voltage of 1.66 V to achieve 100 mA cm −2 at 80 °C, with negligible degradation after 100 h.

Two-dimensional (2D) metal organic frameworks (MOFs) are emerging as low-cost oxygen evolution reaction (OER) electrocatalysts, however, suffering aggregation and poor operation stability. Herein, ultrafine Fe3O4 nanoparticles (diameter: 6 ± 2 nm) are homogeneously immobilized on 2D Ni based MOFs (Ni-BDC, thickness: 5 ± 1 nm) to improve the OER stability. Electronic structure modulation for enhanced catalytic activity is studied via adjusting the amount of Fe3O4 nanoparticles on Ni-BDC. The optimal Fe3O4/Ni-BDC achieves the best OER performance with an overpotential of 295 mV at 10 mA cm-2, a Tafel slope of 47.8 mV dec-1 and a considerable catalytic durability of more than 40 h (less than 5 h for Ni-BDC alone). DFT calculations confirm that the active sites for Fe3O4/Ni-BDC are mainly contributed by Fe species with a higher oxidation state, and the potential-determining step (PDS) is the formation of the adsorbed O* species, which are facilitated in the composite.

Multi-functional small molecules attached to an electrode surface can bind non-covalently to the redox enzyme fructose dehydrogenase (FDH) to ensure efficient electrochemical electron transfer (ET) and electrocatalysis of the enzyme in both mediated (MET) and direct (DET) ET modes. The present work investigates the potential of exploiting secondary, electrostatic and hydrophobic interactions between substituents on a small molecular bridge and the local FDH surfaces. Such interactions ensure alignment of the enzyme in an orientation favourable for both MET and DET. We have used a group of novel synthesized anthraquinones as the small molecule bridge, functionalised with electrostatically neutral, anionic, or cationic substituents. Particularly, we investigated the immobilisation of FDH on a nanoporous gold (NPG) electrode decorated with the novel synthesised anthraquinones using electrochemical methods. The best DET-capable fraction out of four anthraquinone derivatives tested is achieved for an anthraquinone functionalised with an anionic sulphonate group. Our study demonstrates, how the combination of chemical design and bioelectrochemistry can be brought to control alignment of enzymes in productive orientations on electrodes, a paradigm for thiol modified surfaces in biosensors and bioelectronics.

The precise spatial control of the immobilisation of enzymes is necessary for the sequential localisation of an enzymatic cascade. In this contribution, the sequential immobilisation of alcohol dehydrogenase (ADH), formaldehyde dehydrogenase (FLDH) and formate dehydrogenase (FoDH) on self-assembled monolayer modified electrodes has been demonstrated. A range of thiols were screened and optimal enzymatic activity was obtained with thiols bearing -OH, a positively charged heterocyclic aromatic ring and -COOH for the immobilisation of ADH, FLDH and FoDH, respectively. Scanning of the applied potential was utilised to separately modify individual electrodes with the appropriate thiol and enzyme to deliver a three-enzyme system with catalytically active enzyme. Immobilised ADH, FLDH and FoDH retained 46, 32 and 76 % of initial activity, respectively, on storage in aqueous solution at 4 °C for a period of two weeks.

Metal-carbon matrix catalyst has attracted a great deal of interest in electrochemical carbon dioxide reduction reaction (CO2RR) due to its excellent electrocatalytic performance. However, the design of highly active metal–carbon matrix catalyst towards CO2RR using natural biomass and cheap chemical precursors is still under challenge. Herein, a self-assembly strategy, along with CO2 gas as acidifying agent, to fabricate silk fibroin (SF) derived carbon aerogels (CA) combining trace copper nanoparticles (SF-Cu/CA) is developed. Zinc nitrate was introduced as a pore-forming agent to further optimize the pore structure of the as-prepared catalysts to form SF-Cu/CA-1. The rich mesoporous structure and unique constitute of SF-Cu/CA-1 is conducive to exposed numerous active sites, fast electron transfer rate, and the desorption of *CO intermediate, thus leading to the electrocatalytic CO2RR of SF-Cu/CA-1 catalyst with an excellent current density of 29.4 mA cm−2, Faraday efficiency of 83.06% towards carbon monoxide (CO), high the ratio value of CO/H2 (19.58), and a long-term stability over a 10-hour period. This performance is superior to that of SF-Cu/CA catalyst (13.0 mA cm−2, FE CO =58.43%, CO/H2 = 2.16). This work not only offers a novel strategy using natural biomass and cheap chemicals to build metal–carbon matrix catalyst for electrocatalytic CO2-to-CO conversion, but also is expected to promote the industrial-scale implementations of CO2 electroreduction.

Electrochemical sensors embedded in hydrogel-based contact lenses provide valuable health-related information, enabling non-invasive and real-time continuous monitoring. Recently, considerable progress has been made in tear based electrochemical sensors. The scope of reported analytes is continuously expanding. This review identifies key chemical biomarkers (including metabolites, ions, proteins) that can be electrochemically detected in tears. The working principles of i) amperometric enzymatic biosensors, ii) ion-selective sensors for pH and ions, iii) voltammetric sensors and iv) affinity sensors are summarized. This review provides guidelines for the future development of contact lens based electrochemical sensors.

Electrochemical methods can be used to selectively modify the surfaces of electrodes, enabling the immobilization of enzymes on defined areas on the surfaces of electrodes. Such selective immobilization methods can be used to pattern catalysts on surfaces in a controlled manner. Using this approach, the selective patterning of the enzyme glucose oxidase on the electrodes was used to develop a flow reactor for the controlled delivery of the oxidant H2O2. GOx was immobilised on a glassy carbon electrode using polypyrrole, silica films and diazonium linkers. The rate of production of H2O2 and the stability of the response was dependent on the immobilization method. GOx encapsulated in polypyrrole was selected as the optimal method of immobilisation, with a rate of production of 91±11 µM h-1 for 4 hours of continuous operation. The enzyme was subsequently immobilized on carbon rod electrodes (surface area of 5.76 cm2) using a polypyrrole/Nafion® film and incorporated into a flow reactor. The rate of production of H2O2 was 602±57 µM h-1 , with 100% retention of activity after 7 h of continuous operation, demonstrating that such a system can be used to prepare H2O2 at continuous and stable rate for use in downstream oxidation reactions.

The electrochemical carbon dioxide reduction reaction (eCO2RR) is a promising technology that uses electrical energy to catalytically reduce greenhouse gas-CO2, converting CO2 into high value-added products such as hydrocarbons and alcohols. However, due to the complexity of the eCO2RR, the activity and selectivity of the eCO2RR is highly dependent on the intrinsic catalytic activity of a catalyst with mass transportation-favorable morphology. Herein, silk fibroin-derived carbon aerogels (CAs) loaded with small amounts of Cu and Ag nanoparticles were synthesized. Based on the molar content of Cu, the catalysts were labeled SF-CuAg/CA-N (N = 20%, 40%, 60%, 80%). Among them, SF-CuAg/CA-40% showed a good FECO of 71% at −1.26 V vs. a reversible hydrogen electrode (RHE), and a significant current density of −15.77 mA cm−2 towards CO at −1.06 V vs. RHE, which is close to 2.6, 2.53 and 2.71 times those of SF-CuAg/CA-20% (−6.02 mA cm−2), SF-CuAg/CA-60% (−6.24 mA cm−2) and SF-CuAg/CA-80% (−5.82 mA cm−2). The SF-CuAg/CA-N composite materials prepared in this study provide new ideas for the design of highly efficient electrocatalysts for the eCO2RR.

Enzymatic biofuel cells (EBFCs) provide a new strategy to enable direct biomass-to-electricity conversion, posing considerable demand on sequential enzymes. However, artificial blend of multi-enzyme systems often suffer biocatalytic inefficiency due to the rambling mixture of catalytic units. In an attempt to construct a high-performance starch/O

peer-reviewed The full text of this article will not be available in ULIR until the embargo expires on the 08/06/2021 Self-powered drug delivery systems based on conductive polymers (CPs) that eliminate the need for external power sources, are of significant interest for use in clinical applications. Osmium redox polymer mediated glucose/O2 enzymatic biofuel cells (EBFCs) were prepared with an addi-tional CP-drug layer on the cathode. On discharging the EBFCs in the presence of glucose and dioxygen, model drug compounds incorporated in the CP layer were rapidly released with negligible amounts released when the EBFCs were held at open circuit. Controlled and ex situ release of three model compounds, ibuprofen (IBU), fluorescein (FLU) and 4',6-diamidino-2-phenylindole (DAPI), was achieved with this self-powered drug release system. DAPI released in situ in cell culture media was incorporated into retinal pigment epithelium (RPE) cells. This work demonstrates a proof-of-concept responsive drug release system that may be used in implantable devices. ACCEPTED peer-reviewed

The fabrication of a silk fibroin-drived porous, in situ nitrogenated carbon skeleton with highly dispersed Cu–NX–C active sites via a sol–gel and pyrolysis treatment was demonstrated. Cu–NX–C was used to catalyze the oxidative homo-coupling of terminal alkynes with excellent functional group tolerance and high yields under an air atmosphere without base and additives. The small amount of catalyst (2 mol%) and suitable recyclability further demonstrated its good activity and stability. The excellent activity of the Cu–NX–C catalyst can be ascribed to its high surface area, porous structure, small size of the highly dispersed Cu–NX–C active sites and graphitic N. A possible mechanism was deduced according to the structural and surface valence analyses of the sample before and after the reaction. The report aims to demonstrate that such a nature-based sustainable catalyst can provide new insights into the design of coupling reaction catalysts with outstanding catalytic C–C coupling performance.

Retinal image analysis has become the main non-invasive way to diagnose many diseases, and the extraction of blood vessels is the most important step. Supervised learning method has a good effect on blood vessel extraction. In order to further improve the accuracy of detection, a low-scales vessel detection (LVD) algorithm is proposed. In addition to a sub-network for extracting features in the original scale, two sub-networks for extracting features in the low scale are added, and the single output in the low scale is fused with the features in the original size, and the final output result is obtained after dimensionality reduction. Considering the structural characteristics of fundus vessels, an asymmetric depth-fixed sub-network (ADS) with deep layers and fewer parameters is designed in LVD. Tested in the public database DRIVE, only the green component of color fundus image and B-COSFIRE filter response are used as feature input. Its sensitivity, specificity, accuracy and AUC index are 0.8192, 0.9842,0.9695 and 0.9782, respectively, which reach the advanced level.

Following a renaissance from the 1980s, electrochemistry has developed into sophisticated interdisciplinary science integrating solid-state and surface science and further, biological sciences. Most remarkably, even the single-molecule can now be addressed. Single-molecule electrochemistry covers transition metal complexes, organic redox molecules, fragile biomolecules, and molecular-scale hybrids between metallic nanoparticles and complex molecules, supported by new theoretical frames. We overview here selected areas of molecular scale electrochemistry. After a theoretical minimum, we address complex molecules in electron transfer, enzyme catalysis, and nanoparticle catalysis. Our focus is on issues not so much previously highlighted, such as competition between superexchange and sequential conduction, and resonance features in the transition between the two limits. Another aspect is coherent multi-electron transfer for large bias voltages often needed to drive enough current through solute molecular junctions. We note finally some single-molecule perspectives relating to DNA-based molecules and to spin transitions via chiral molecules.

Enzymatic bioelectrochemistry represents the marriage of electrochemistry and enzymatic biocatalysis, and has led to important applications for biosensors, biofuel cells, and bioelectrocatalysis. Enzyme immobilization is the basis of enzymatic bioelectrochemistry, as immobilization itself determines the enzyme/material interface and thus the electrochemical performance. Amongst the range of methods of enzyme immobilization, one-step electrochemical approaches feature rapid immobilization and good control over the processes, enabling par?tial or total use of the electrode surface. In this mini-review, we first briefly introduce the operating principles of bioelectrochemical applications based on enzyme modified electrodes. We then overview recent progress in utilizing conductive polymers, redox-active modified polymers, sol–gel silica and electrochemically assistant adsorption for enzyme immobilization via one-step electrochemical approaches. The use of conductive polymers for in situ enzyme immobilization is our major focus. Perspectives for future work are also described.

Blue copper enzymes often show no voltammetry themselves, whereas substrate binding triggers strong electrocatalytic signals. Similarly, electrochemical STM only gives strong contrasts when substrate (O2, NO2-) is present. AFM shows that CuNIR on Au(111)-electrodes modified by self-assembled cysteamine monolayers (SAMs) maintains constant height throughout the electrocatalytic range, while NO2- triggers substantial enzyme ‘swelling’. ‘Swelling’ does not accord with the crystalline state, which, however, is not the relevant catalytic environment.With a view on understanding these patterns, we present ab initio quantum chemical studies of CuNIR/OH2 and CuNIR/NO2- 740-atom fragments including the type I and type II Cu-centres. Replacing water at the type II centre by nitrite triggers 2-Å Cu–Cu distance increase, according with enzyme ‘swelling’. 2 Å Cu–Cu increase would close intramolecular ET entirely, but is compensated by efficient superexchange alignment of closely interacting LUMOs and HOMOs. In the water-bound enzyme these orbitals are separated by unfavourable through-space tunneling regions.

Featuring high electrical conductivity and electrochemical activity, transition metal sulfides are promising materials for the positive electrode of hybrid supercapacitors. However, considering their poor cycling life and rate performance, critical challenges remain. In this contribution, we describe hollow NiS2/CoS2@C composites obtained by stepwise etching, annealing, and sulfuration of ZIF-67. Specifically, NiS2/CoS2 particles were dispersed on N/S co-doped carbon nanocages and found to exhibit outstanding stability and rate performance. The unique nanocage structure of N/S co-doped carbon and heterogeneous interfaces of NiS2 and CoS2 can promote both ion transport and electron transfer, enriching the active site for enhanced reactivity. The resulting NiS2/CoS2@C nanocage composites in fact showed considerable electrochemical performance, with a specific capacity of 1373 C g-1 at 1 A g-1. When combined with reduced graphene oxide (RGO)-based negative electrode, the assembled hybrid supercapacitor registered an energy density of 63.3 Wh kg-1 at a power density of 800 W kg-1, retaining exceeding 98% of the initial capacity even after 13,000 cycles.

Bioelectrochemical dioxygen reduction reaction (ORR) catalyzed by multi-copper oxidases (MCOs) is a process of paramount importance occurring at the cathode of enzymatic biofuel cells (EBFCs), which is an energy harvester that holds promise of self-sustained implantable and wearable medical devices. The MCO biocathode is, however, frequently the limiting factor of a working EBFC. Besides the operational stability issue, enzymatic biocathodes are largely constrained by the relatively low solubility of dioxygen in aqueous solution. As an emerging topic, we here review the introduction of dioxygen-enriching materials to the cathodic bioelectrode for overcoming the dioxygen supply limitation, leading to improved ORR performance.

Direct electron transfer (DET) of enzymes on electrode surfaces is highly desirable both for fundamental mechanistic studies and to achieve membrane- and mediator-less bioenergy harvesting. In this report, we describe the preparation and comprehensive structural and electrochemical characterization of a three-dimensional (3D) graphene-based carbon electrode, onto which the two-domain redox enzyme Myriococcum thermophilum cellobiose dehydrogenase (MtCDH) is immobilized. The electrode is prepared by an entirely novel method, which combines in a single step electrochemical reduction of graphene oxide (GO) and simultaneous electrodeposition of positively charged polyethylenimine (PEI), resulting in a well dispersed MtCDH surface. The resulting MtCDH bio-interface was characterized structurally in detail, optimized, and found to exhibit a DET maximum current density of 7.7 ± 0.9 μA cm−2 and a half-lifetime of 48 h for glucose oxidation, attributed to favorable MtCDH surface orientation. A dual, entirely DET-based enzymatic biofuel cell (EBFC) was constructed with a MtCDH bioanode and a Myrothecium verrucaria bilirubin oxidase (MvBOD) biocathode. The EBFC delivers a maximum power density (Pmax) of 7.6 ± 1.3 μW cm−2, an open-circuit voltage (OCV) of 0.60 V, and an operational lifetime over seven days, which exceeds most reported CDH based DET-type EBFCs. A biosupercapacitor/EBFC hybrid was also constructed and found to register maximum power densities 62 and 43 times higher than single glucose/air and lactose/air EBFCs, respectively. This hybrid also shows excellent operational stability with self-charging/discharging over at least 500 cycles.

Some plants and insects exhibit superhydrophobicity in nature. Inspired by this, many researchers have designed superhydrophobic surfaces by studying the structures of those plants and animals. Hence, man-made superhydrophobic surfaces have gained tremendous interest because they can be used in diverse fields. Superhydrophobicity occurs by combining micro-/nanoscale rough structures with low surface energy materials to produce a water-repelling surface. However, superhydrophobic surfaces have not been able to be used in real life applications because of their poor durability and short life span. Self-healing is a good strategy to increase the resilience and life span of a superhydrophobic surface. It has been suggested that embedding a superhydrophobic surface with a self-healing ability will extend the lifespan of the surface for practical applications. A lot of reviews talk about superhydrophobic surfaces but very few discuss self-healing superhydrophobic surfaces. In this review, recent progress in the fabrication of self-healing superhydrophobic surfaces, characterization, applications of superhydrophobic surfaces and different methods for fabrication are discussed. Also, some ideas for the way forward on future researches are discussed.

International audience; The ever-increasing demands for clean and sustainable energy sources combined with rapid advances in biointegrated portable or implantable electronic devices have stimulated intensive research activities in enzymatic (bio)fuel cells (EFCs). The use of renewable biocatalysts, the utilization of abundant green, safe, and high energy density fuels, together with the capability of working at modest and biocompatible conditions make EFCs promising as next generation alternative power sources. However, the main challenges (low energy density, relatively low power density, poor operational stability, and limited voltage output) hinder future applications of EFCs. This review aims at exploring the underlying mechanism of EFCs and providing possible practical strategies, methodologies and insights to tackle these issues. First, this review summarizes approaches in achieving high energy densities in EFCs, particularly, employing enzyme cascades for the deep/complete oxidation of fuels. Second, strategies for increasing power densities in EFCs, including increasing enzyme activities, facilitating electron transfers, employing nanomaterials, and designing more efficient enzyme-electrode interfaces, are described. The potential of EFCs/(super)capacitor combination is discussed. Third, the review evaluates a range of strategies for improving the stability of EFCs, including the use of different enzyme immobilization approaches, tuning enzyme properties, designing protective matrixes, and using microbial surface displaying enzymes. Fourthly, approaches for the improvement of the cell voltage of EFCs are highlighted. Finally, future developments and a prospective on EFCs are envisioned.

The conversion of CO2 into carbon-based fuels via electrochemical reduction is a promising approach to realizing the termination of carbon cycling. Copper (Cu0) is considered to be an effective electrochemical catalyst for such purpose. However, it is limited by its instability and low selectivity. In this work, Cu2+ was embedded into a polycondensation structure of resorcinol (R) and formaldehyde (F) via sol-gel reaction, and the complex was then calcined at high temperature to obtain copper nanoparticles-dispersed carbon aerogels (Cu/CA). The samples were further activated sequentially under CO2 and N2 atmosphere. The final products under different activation temperature of secondary N2 atmosphere were obtained and marked as Cu/CA-CO2-N2-T. The existence of highly dispersed Cu0 on the carbon aerogels was confirmed by XPS and HRTEM, which exhibited attractive activity towards electrochemical CO2 reduction reaction (CO2RR) forming carbon product in 0.1 M KHCO3 aqueous media. Furthermore, the CO2RR product distribution varied under different samples. The sample activated under 700 °C (Cu/CA-CO2-N2-700) with Cu loading c.a. 5.13 wt% showed remarkable CO faradaic efficiency (FE) (75.6%) at low overpotential of −0.49 V. Further calcination led to more exposure of copper, and CO dimerization to C2 product. The high selectivity toward CO by Cu/CA-CO2-N2-700 maybe attributed to their excellent stability in maintaining the metallic nature of Cu component within the hydrophobic carbon aerogels during electrocatalysis, which further prevents the adsorption and reduction of CO on the catalyst.

Hollow nanostructured materials present a class of promising electrode materials for energy storage and conversion. Herein, 3D hollow nitrogen-doped carbon shells decorated with well-defined cobalt sulfide nanoparticles (Co9S8 /HNCS) have been constructed for superior lithium and sodium storage. Two steps are involved in the designed preparation procedure. First, hollow intermediates with preserved cobalt components are controllably fabricated by simultaneously dissociating cobalt containing zeolitic-imidazolate-frameworks-67 (ZIF-67), and polymerizing dopamine in a Tris–HCl solution (pH = 8.5). The polydopamine (PDA) wrapped intermediates inherits the polyhedral structure of the ZIF-67 crystals. In the second step, the final Co9S8 /HNCS composite is obtained via a combined carbonization and sulfurization treatment of the intermediates, allowing the formation of hollow polyhedrons of nitrogen-doped carbon shells (900±100 nm) derived from PDA and the encapsulation of highly uniform cobalt sulfide nanoparticles (11±2 nm). This configuration is believed to not only shorten the lithium or sodium ion diffusion distance and accommodate volume change during lithium or sodium ion insertion/extraction, but also to enhance the overall electrical conductivity and the number of active sites. As a result, the Co9S8 /HNCS composite exhibits an impressive reversible capacity of 755 mA h g-1 at 500 mA g-1 after 200 cycles for lithium ion storage, and capacities of 327 mA h g-1 at 500 mA g-1 after 200 cycles and 224 mA h g-1 at 1000 mA g-1 after 300 cycles for sodium ion storage. Essential factors especially the structural stability during cycling have been identified, and the discharge/charge mechanism is discussed.

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Metal-carbon matrix catalyst has attracted a great deal of interest in electrochemical carbon dioxide reduction reaction (CO

Transition metal phosphides are promising oxygen evolution reaction (OER) catalysts due to their earth-abundant and cost-effective features. Here, nanostructured CoP nanoparticles locked in hollow nitrogen doped carbon frameworks (CoP@HNC) were successfully designed and characterized for their morphology, composition, and electrochemistry. In a typical low-temperature phosphorization process, the Co species in carbonized poly-dopamine (PDA) coated ZIF-67 are converted to either hollow CoP or small-sized solid CoP nanoparticles governed by the nanoscale Kirkendall effect. The PDA layers derived nitrogen-doped carbon components feature a hollow polyhedral structure, with CoP nanoparticles imbedded in the shell. CoP@HNC demonstrates a low overpotential of 327 mV for 10 mA cm-2 and a good operational stability (72 h) for alkaline OER. The HNC encapsulation affords the low electronic resistance between CoP nanoparticles, as well as the mechanical and chemical stability of composites by preventing the aggregation of CoP nanoparticles during the OER process.

Designing efficient and robust nonprecious metal-based electrocatalysts for overall water electrolysis, which is mainly limited by the oxygen evolution reaction (OER), for hydrogen production remains a major challenge for the hydrogen economy. In this work, a bimetallic NiFeP catalyst is coated on nickel phosphide rods grown on nickel foam (NiFeP@NiP@NF). This self-supported and interfacially connected electrode structure is favorable for mass transfer and reducing electrical resistance during electrocatalysis. The preparation of NiFeP@NiP@NF is optimized in terms of (i) the coprecipitation time of the NiFe Prussian blue analogue layer that serves as phosphides precursor and (ii) the phosphidation temperature. The optimized sample exhibits excellent OER performance delivering current densities of 10 and 100 mA cm-2 at low overpotentials of 227 and 252 mV in 1.0 M KOH, respectively, and maintaining 10 mA cm-2 for more than 120 h without obvious degradation. Moreover, it can also be operated as a hydrogen evolution electrocatalyst, requiring an overpotential of 105 mV at 10 mA cm-2 in the same medium. Thus, the as-prepared material was tentatively utilized as a bifunctional electrocatalyst in a symmetric electrolyzer, requiring a voltage bias of 1.57 V to afford 10 mA cm-2 in 1.0 M KOH, while exhibiting outstanding stability.

Celebrating the electrochemistry legacy: Prof. Zhang was a member of the Editorial Board of ChemElectroChem as well as a valued author and reviewer. Together with her friends and colleagues Christian Engelbrekt, Xinxin Xiao and Jens Ulstrup (Technical University of Denmark) as well as Bingwei Mao (Xiamen University, China), we hope to commemorate Prof Zhang′s contributions to the electrochemical sciences by this Special ChemElectroChem Collection on the theme of “Electrochemical Materials and Interfaces”.