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Water electrolysis is a promising technology to produce hydrogen but it was severely restricted by the slow oxygen evolution reaction (OER). Herein, we firstly reported an advanced electrocatalyst of MOF-derived hollow Zn–Co–Ni sulfides (ZnS@Co9S8@Ni3S2-1/2, abbreviated as ZCNS-1/2) nanosword arrays (NSAs) with remarkable hydrogen evolution reaction (HER), OER and corresponding water electrolysis performance. To reach a current density of 10 mA cm−2, the cell voltage of assembled ZCNS-1/2//ZCNS-1/2 for urea electrolysis (1.314 V) is 208 mV lower than that for water electrolysis (1.522 V) and stably catalyzed for over 15 h, substantially outperforming the most reported water and urea electrolysis electrocatalysts. Density functional theory calculations and experimental result clearly reveal that the properties of large electrochemical active surface area (ECSA) caused by hollow NSAs and fast charge transfer resulted from the Co9S8@Ni3S2 heterostructure endow the ZCNS-1/2 electrode with an enhanced electrocatalytic performance.

The electrochemical performance of solid oxide cells (SOCs) is investigated under both fuel cell and electrolyzer operations to understand their asymmetric behavior between the two operation modes. The current–voltage and electrochemical impedance characteristics of a hydrogen-electrode-supported cell are experimentally analyzed. Also, a numerical model is developed to reproduce the cell performance and to understand the internal resistances of the cell. Partial pressures of supplied gas and load current are varied to evaluate their effects on the cell performance. The gas partial pressures of hydrogen and steam supplied to the hydrogen electrode are kept equivalent so that the cell performance can be fairly compared between the two operation modes when the same current is applied. It is found that the origin of the asymmetry is mostly from the hydrogen electrode; both activation and concentration overpotentials show asymmetric behavior particularly at high current densities. A numerical experiment is also conducted by deliberately changing parameters in the model. Asymmetry in the activation overpotential is found to be originated from the non-identical charge-transfer coefficients in the Butler–Volmer equation and also from the non-uniform gas concentration formed in the hydrogen electrode under current-biased conditions. On the other hand, asymmetry in the concentration overpotential is associated with the non-equimolar counter diffusion of hydrogen and steam caused by the effect of Knudsen diffusion. Therefore, enhancing gas transport in the hydrogen electrode and reducing the contribution of Knudsen diffusion are effective approaches to reduce asymmetry not only in the concentration overpotential but also in the activation overpotential.

Effective and robust electrocatalysts are mainly based on innovative materials and unique structures. Herein, we designed a flakelike cobalt phosphide-based catalyst supporting on NiCo2O4 nanorods array, which in-situ grew on the nickel foam (NF) current collector, referring as N–Co2P/NiCo2O4/NF electrode. By optimizing the microstructure and electronic structure through 3D hierarchy fabrication and nitrogen doping, the catalyst features with abundant electrochemical surface area, favorable surface wettability, excellent electron transport, as well as tailored d band center. Consequently, the as-prepared N–Co2P/NiCo2O4/NF electrode exhibits an impressive HER activity with a low overpotentials of 58 mV at 10 mA cm−2, a Tafel slop of 75 mV dec−1, as well as superior durability in alkaline medium. This work may provide a new pathway to effectively improve the hydrogen evolution performance of transition metal phosphides and to develop promising electrodes for practical electrocatalysis.

Co–N–C is a promising oxygen electrochemical catalyst due to its high stability and good durability. However, due to the limited adsorption ability improvement for oxygen-containing intermediates, it usually exhibits inadequate catalytic activity with 2-electron pathway and high selectivity of hydrogen peroxide. Herein, the adsorption of Co–N–C to these intermediates is modulated by constructing heterostructures using transition metals and their derivatives based on d-band theory. The heterostructured nanobelts with MoC core and pomegranate-like carbon shell consisting of Co nanoparticles and N dopant (MoC/Co–N–C) are engineered to successfully modulate the d band center of active Co–N–C sites, resulting in a remarkably enhanced electrocatalysis performance. The optimally performing MoC/Co–N–C exhibits outstanding bi-catalytic activity and stability for the oxygen electrochemistry, featuring a high wave-half potential of 0.865 V for the oxygen reduction reaction (ORR) and low overpotential of 370 mV for the oxygen evolution reaction (OER) at 10 mA cm−2. The zinc air batteries with the MoC/Co–N–C catalyst demonstrate a large power density of 180 mW cm−2 and a long cycling lifespan (2000 cycles). The density functional theory calculations with Hubbard correction (DFT + U) reveal the electron transferring from Co to Mo atoms that effectively modulate the d band center of the active Co sites and achieve optimum adsorption ability with “single site double adsorption” mode.

A novel strategy was developed to fabricate FeNx-doped carbon quantum dots (Fe-N-CQDs) to detect Cu2+ ions selectively as a fluorescence probe. The Fe-N-CQDs were synthesized by an efficient electrolysis of a carbon cloth electrode, which was coated with monoatomic iron-anchored nitrogen-doped carbon (Fe-N-C). The obtained Fe-N-CQDs emitted blue fluorescence and possessed a quantum yield (QY) of 7.5%. An extremely wide linear relationship between the Cu2+ concentration and the fluorescence intensity was obtained in the range from 100 nM to 1000 nM (R2 = 0.997), and the detection limit was calculated as 59 nM. Moreover, the Fe-N-CQDs demonstrated wide range pH compatibility between 2 and 13 due to the coordination between pyridine nitrogen and Fe3+, which dramatically reduced the affection of the protonation and deprotonation process between H+ and Fe-N-CQDs. It is notable that the Fe-N-CQDs exhibited a rapid response in Cu2+ detection, where stable quenching can be completed in 7 s. The mechanism of excellent selective detection of Cu2+ was revealed by energy level simulation that the LUMO level of Fe-N-CQDs (−4.37 eV) was close to the redox potential of Cu2+, thus facilitating the electron transport from Fe-N-CQDs to Cu2+.

To clarify the anodic dissolution mechanism of Mg, the hydrogen evolution from pure Mg in acidic solutions under galvanostatic conditions were systematically measured. With increasing anodic current density, the cathodic hydrogen evolution rate decreased, and the anodic hydrogen evolution became faster while some surface area on the Mg was becoming dark under anodic polarization. Based on the surface analysis results and the generally accepted basic electrochemical equations, the evolution kinetics of hydrogen from Mg was deduced, and the most possible surface intermediate active species that could facilitate the anodic Mg dissolution and anodic hydrogen evolution were proposed. This paper further develops the model of incomplete film Mg+ dissolution, explains many reported experimental phenomena, and clarifies misunderstandings of current mechanism.

Rechargeable magnesium batteries (RMBs), as one of the most promising candidates for efficient energy storage devices with high energy, power density and high safety, have attracted increasing attention. However, searching for suitable cathode materials with fast diffusion kinetics and exploring their magnesium storage mechanisms remains a great challenge. CuS submicron spheres, made by a facile low-temperature synthesis strategy, were applied as the high-performance cathode for RMBs in this work, which can deliver a high specific capacity of 396 mAh g−1 at 20 mA g−1 and a remarkable rate capacity of 250 mAh g−1 at 1000 mA g−1. The excellent rate performance can be assigned to the nano needle-like particles on the surface of CuS submicron spheres, which can facilitate the diffusion kinetics of Mg2+. Further storage mechanism investigations illustrate that the CuS cathodes experience a two-step conversion reaction controlled by diffusion during the electrochemical reaction process. This work could make a contribution to the study of the enhancement of diffusion kinetics of Mg2+ and the reaction mechanism of RMBs.

In this work, a novel bamboo-like carbon nanotubes@Sn4P3@carbon (BLCNTs@Sn4P3@C) coaxial nanotubes are designed and prepared using a newly developed hydrothermal method followed by a phophidation process. The prepared Sn4P3 nanoparticles are uniformly coated and wrapped on the one-dimensional (1D) bamboo-like CNTs, which is covered by a uniform carbon layer to form a sandwich-like structure with Sn4P3 in between. The inner CNT and outer carbon can effectively maintain the structural stability and serve as the good electron conductors. Additionally, the outer carbon coating layer can effectively keep BLCNTs@Sn4P3@C nanotubes separate each other, preventing aggregation of Sn4P3 during charge/discharge when this material is used as anode for sodium ion batteries. The anode of BLCNTs@Sn4P3@C shows excellent reversible capacity and a long cycling of over 2000 cycles. The unique design of coaxial nanotubes is greatly beneficial to the electrochemical performance of Sn4P3 for sodium ion storage.

Hydrogen (H2) is the future energy carrier and it is quite challenging to produce at a large-scale on economic basis. The water splitting technique has achieved a good place in H2 production. To generate efficient electrocatalysts for the Hydrogen evolution reaction (HER), low-cost synthetic designs are necessary. In our study, a one-step co-precipitation reduction process was used to synthesize NiWS electrocatalyst. The crystalline structure, phase purity, elemental composition and the surface morphology of the as-prepared samples have been examined by different characterization techniques. These techniques have proved that the elemental presence and formation of NiWS with high crystalline nature (rhombohedral). Furthermore, the performance of the electrocatalyst towards HER has been evaluated through electrochemical methods. On analysis, NiWS/CNT showed an excellent electrochemical activity of 175 mV, and pure NiWS showed 201 mV at 10 mA/cm2 in an alkaline electrolyte. These over-potential values are lower than HER in acid and neutral electrolytes. Further, the as-prepared NiWS/CNT proved to be a highly stable and efficient platinum-free electrocatalyst for HER.

In this study, cost-effective anthracite and industrial silicon powder were used as precursor and catalyst, respectively, to prepare graphite with various structure, during which the catalytic mechanism was analyzed. The results demonstrate that the as-obtained sample with 5% silicon catalyst (G-2800-5%) exhibits the best overall lithium storage performance. In detail, G-2800-5% display the best graphite structure with graphitization degree of 91.5%. As anode materials, a high reversible capacity of 369.0 mAh g−1 can be achieved at 0.1 A g−1. Meanwhile, the reversible capacity of 209.0 mAh g−1 can be obtained at the current density of 1 A g−1. It also delivers good cyclic stability with a 92.2% retention after 200 cycles at 0.2 A g−1. The highly developed graphite structure, which is favorable to the formation of stable SEI and reduced lithium ion loss should be responsible for the superior electrochemical performance.

High-energy-density lithium-sulfur batteries has attracted substantial attention as competitive candidates for large-scale energy storage technologies. Still, the adverse “shuttle effect” and sluggish sulfur conversion reaction kinetics immensely obstruct their commercial viability. Herein, a two-dimensional metallic 1T phase WS2 (1T-WS2) nanosheets modified functional separator is developed to improve the electrochemical performance. Meanwhile, the semiconducting bulk-WS2 crystals, and 2H phase WS2 (2H-WS2) nanosheets with more basal-plane S-vacancy defects are also prepared to probe the contributions of the crystal structure (phase), S-vacancy defects, and edges to the Li–S batteries performance experimentally and theoretically. In merits of the synergistic effect of high ion and electron conductivity, enhanced binding ability to lithium polysulfides (LiPSs), and sufficient electrocatalytic active sites, the 1T-WS2 shows highly efficient electrocatalysis of LiPSs conversion and further improves Li–S battery performance. As expected, thus-fabricated cells with 1T-WS2 nanosheets present superior cycle stability that maintain capacity decline of 0.039% per cycle after 1000 cycles at 1.0 C. The strategy presented here offers a viable approach to reveal the critical factors for LiPSs catalytic conversion, which is beneficial to developing advanced Li–S batteries with enhanced properties.

Sustainable development based on the value-added utilization of furfural residues (FRs) is an effective way to achieve a profitable circular economy. This comprehensive work highlights the potential of FRs as precursor to prepare porous carbons for high performance supercapacitors (SCs). To improve the electrochemical performance of FR-based carbon materials, a facile route based on methanol pretreatment coupled with pre-carbonization and followed KOH activation is proposed. More defects could be obtained after methanol treatment, which is incline to optimize textural structure. The activated methanol treated FR-based carbon materials (AFRMs) possess high specific surface area (1753.5 m2 g−1), large pore volume (0.85 cm3 g−1), interconnected micro/mesoporous structure, which endow the AFRMs with good electrochemical performance in half-cell (326.1 F g−1 at 0.1 A g−1, 189.4 F g−1 at 50 A g−1 in 6 M KOH). The constructed symmetric SCs based on KOH, KOH–K3Fe(CN)6 and KOH-KI electrolyte deliver energy density up to 8.9, 9.9 and 10.6 Wh kg−1 with a capacitance retention of over 86% after 10,000 cycles. Furthermore, the self-discharge can be restrained by the addition of K3Fe(CN)6 and KI in KOH electrolyte. This study provides an effective approach for high-valued utilization of FR waste.

A mechanically strong binder with polar functional groups could overcome the dilemma of the large volume change during charge/discharge processes and poor cyclability of lithium-sulfur batteries (LSBs). In this work, for the first time, we report the use of poly(thiourea triethylene glycol) (PTTG) as a multifunctional binder for sulfur cathodes to enhance the performance of LSBs. As expected, the PTTG binder facilitates the high performance and stability delivered by the Sulfur-PTTG cathode, including a higher reversible capacity of 825 mAh g−1 at 0.2 C after 80 cycles, a lower capacity fading (0.123% per cycle) over 350 cycles at 0.5 C, a higher areal capacity of 2.5 mAh cm−2 at 0.25 mA cm−2, and better rate capability of 587 mAh g−1 at 2 C. Such superior electrochemical performances could be attributed to PTTG's strong chemical adsorption towards polysulfides which may avoid the lithium polysulfide shuttle effect and excellent mechanical characteristics which prevents electrode collapse during cycling and allows the Sulfur-PTTG electrode to maintain robust electron and ion migration pathways for accelerated redox reaction kinetics.

Hydrogen technology is widely considered a novel clean energy source, and electrolysis is an effective method for hydrogen evolution. Therefore, efficient hydrogen evolution reaction (HER) catalysts are urgently needed to replace precious metal catalysts and meet ecological and environmental protection standards. Herein, Ni–Mn–P electrocatalysts are synthesized using facile electrodeposition technology. The influence of the Mn addition on the catalytic behavior is studied by the comprehensive analysis of catalytic performance and morphology of the catalysts. Among them, the Ni–Mn–P0.01 catalyst exhibits small coral-like structures, greatly improving the adsorption and desorption of hydrogen ions and reducing the overpotential hydrogen evolution. Consequently, overpotential at 10 mA cm−2 electric current density is 113 mV, and the value of the Tafel slope achieves 74 mV/dec. Furthermore, the Ni–Mn–P catalyst shows long-time (20 h) stability at current densities of 10 and 60 mA/cm2. The results confirm that the synergistic effect of Ni, Mn, and P accelerates the electrochemical reaction. Meanwhile, the addition of manganese element can change the micromorphology of the catalyst, thereby exposing more active sites to participate in the reaction, enhancing water ionization, improving the catalytic performance. This study opens a new way toward improving the activity of the catalyst by adjusting Mn concentration during the electrodeposition process.

Corrosion behavior of AZ31 magnesium alloy in NH4+-bearing chloride solution with controlled pH was investigated by weight loss experiment, hydrogen collection, and electrochemical test combined with surface morphology and topography observation. The results show that NH4+ and pH of the solution can affect the corrosion of AZ31 magnesium alloy. The existence of NH4+ affects the formation and dissolution of corrosion products, which makes the protective effect of the corrosion product layer weaker. The change of pH value not only affects the corrosion mechanism of AZ31, but also alters the concentration of NH4+ ions in the solution, which further influences the corrosion product layer of AZ31, and finally makes the corrosion of AZ31 change significantly.

To monitor the reaction between Ce4+ ion and Cl– ion at the electron level, an electrochemical experiment was designed in this work. Herein, the intermediate and final products that may be produced during the redox reaction are directly tracked by using cyclic voltammetry, and the influences of Ce4+ ion concentration, temperature and F– ion on the reduction peak potential of Ce4+ ion were investigated. The results show that Ce4+ ion reacts with Cl– ion through an irreversible reaction without any intermediate products, and the rate-determining step of the reaction is diffusion during the electrode reaction. The effects of temperature (20–40 °C) and Ce4+ ion concentration (0.04–0.12 mol/L) on the reduction peak potential of Ce4+ ion can be ignored, but the higher the molar ratio of F– to Ce4+ (0–3 mol/mol), the more easily the reduction of Ce4+ ion to Ce3+ ion occurs. Additionally, the Ce4+ ions are preferentially reduced by thiourea when thiourea is added in the HCl solution, and thiourea inhibits the oxidation of Cl– ions to Cl2 by forming a complex with Cl– ions. This work provides a theoretical basis for the role of thiourea in inhibiting Cl2 production and offers a new way to find new reductants.

As one of the most common cathode materials for aqueous zinc-ion batteries (AZIBs), manganese oxides have the advantages of abundant reserves, low cost, and low toxicity. However, the electrochemical mechanism at the cathode of aqueous zinc–manganese batteries (AZMBs) is complicated due to different electrode materials, electrolytes and working conditions. These complicated mechanisms severely limit the research progress of AZMBs system and the design of cells with better performance. Hence, the mechanism of AZMBs currently recognized by most researchers according to the classification of the main ions involved in faradaic reaction are introduced in the review. Then a series of reasons that affect the electrochemical behavior of the battery are summarized. Finally, the failure mechanisms of AZMBs over prolonged cycling are discussed, and the current insufficient research areas of the system are explained, along with the direction of further research being prospected.

Reasonable construction of sulfur host with high conductivity, large sulfur storage gap, strong chemical adsorption, and fast oxidation-reduction kinetics of polysulfide is very significant for its practical use in lithium-sulfur batteries (LSBs). In this paper, the surface modification of MIL-88A(Fe) is carried out by Dawson-type polyoxometalate (POM), and a hollow capsule shell material with P2W18, Fe3O4, and C components is synthesized by the subsequent carbonization process. When applied as the sulfur host, the hollow capsule shell material can efficiently improve the conductivity of sulfur electrode and restrain the volumetric change of active sulfur while charging and discharging. On this foundation, electrochemical analysis and density functional theory (DFT) calculation show that the P2W18 on the outer layer of the capsule shell have effective electrocatalytic activity and potent chemical bond on the lithium polysulfides (LiPSs), which is helpful to block the shuttle effect. Therefore, the as-assembled LSBs display the outstanding specific capacity and prominent cycle stability. Specifically, it delivers an excellent reversible capacity of 1063 mAh/g after 100 cycles of charge–discharge at a rate of 0.5 C, accounting for a preservation by 96% in comparison to that of the initial cycle. Moreover, even after 2000 cycles at 1 C, the reversible specific capacity of 585 mAh/g can still be maintained with an average decay rate of only 0.021%.

Efficient and cheap oxygen evolution reaction (OER) catalysts play an important role in electrochemical energy storage and conversion devices. Transition metal nitrides (TMNs) show excellent OER performance mainly because of their unique electronic structure and high electrical conductivity. In this paper, we report a systematic study in order to explore the relationship between nitrogen deficiency and the OER activity of well-defined Co4N1-x (x > 0) thin film electrodes prepared by magnetron sputtering. The nitrogen deficiency is regulated by changing the Ar-N2 flow ratio and annealing at high temperatures. We find that by decreasing nitrogen content, the surface of Co4N1-x film is more prone to be oxidized with forming a surface Co N O layer. The electrochemical measurements imply that the OER activity can be improved by introducing nitrogen deficiency. The above results could be ascribed to better bulk electrical conductivity and a higher surface ratio of Co3+ in more nitrogen-deficient electrocatalysts. These results possibly provide a new and facile route to promote the OER activity by tuning the nitrogen deficiency in TMNs.

The present work illustrates a novel approach for the maskless and resistless fabrication of nanopatterned metal layers on Si substrates, based on the combination of nanomechanical surface modification techniques (such as nanoindentation and nanoscratching) and electrodeposition. Single crystal (1 0 0) n -doped Si substrates were first cleaned from native oxide. Nanoindentation and nanoscratching were then used to locally change the substrate microstructure and create regions with reduced electrical conductivity. The substrates were finally mounted as cathode electrodes in a three-electrode electrochemical cell to potentiostatically deposit a Ni layer. Electrodeposition was prevented in regions with modified microstructure, enabling the formation of a patterned Ni layer. The fabrication of several patterns including continuous Ni lines of 200 nm width and several microns length was obtained.

Electrochemical CO2 reduction to higher-value hydrocarbons beyond C1 products has attracted much attention recently. Single-atom catalysts (SACs) are regarded as promising CO2 reduction electrocatalysts. However, most SACs only show activity to C1 products. In this work, we considered the activity and the synergetic effect of dual active sites for metal SACs supported on graphitic carbon nitride (g-C3N4) as CO2 reduction electrocatalysts. Density functional theory (DFT) calculations are employed. First, by using the adsorption energies of CO* on the metal site and that of H* on the nitrogen site as bi-descriptors, we predicted seven out of 14 metal centers have the propensity to generate beyond CO products. To further evaluate the catalyst activity on beyond CO product formation, we established reaction pathways towards ethylene through M/N or M/C. Ru has the best performance (the limiting potential is −0.90 V) by taking M/N as active sites. A dual volcano-shaped plot is built up based on the CO adsorption energies on metal sites, which can be used to indicate whether M/C or M/N shows better performance for a specific metal center. Our work shed light on developing criteria to guide the design of CO2 reduction electrocatalysts with dual active sites.

The superlattice La-Y-Ni-based hydrogen storage alloys have high discharge capacity and are easy to prepare. However, there is still a gap in commercial applications because of the severe corrosion of the alloy in electrolyte and poor high-rate dischargeability (HRD). Therefore, (LaSmY)(NiMnAl)3.5 alloy was prepared by magnetic levitation induction melting, and then the alloy was coated with different contents (0.1 wt%–1.0 wt%) of nano-carbons by low-temperature sintering with sucrose as the carbon source in this work. The results show that the cyclic stability and HRD of the alloy first increase and then decrease with the increase of carbon contents. The kinetic results show that the electrocatalytic activity and conductivity of the alloy electrodes can be enhanced by carbon coating. The electrochemical properties of the alloy are the best when the carbon coating content is 0.3 wt%. Compared with the uncoated alloy, the maximum discharge capacity (Cmax) improves from 354.5 to 359.0 mAh/g, the capacity retention rate after 300 cycles (S300) enhances from 73.15% to 80.01%, and the HRD1200 of the alloy enhances from 74.39% to 74.39%.

Pd modified electrodes possess problems such as easy agglomeration and low electrolytic ability, and the use of manganese dioxide (MnO2) to facilitate Pd reduction of organic pollutants is just started. However, there is still a limited understanding of how to match the Pd load and MnO2 to realize optimal dechlorination efficiency at minimum cost. Here, a Pd/MnO2/Ni foam cathode was successfully fabricated and applied for the efficient electrochemical dechlorination of 2,4,6-trichlorophenol (2,4,6-TCP). The optimal electrocatalytic hydrodechlorination (ECH) performance with 2,4,6-TCP dechlorination efficiency (92.58% in 180 min) was obtained when the concentration of PdCl2 precipitation was 1 mmol/L, the deposition time of MnO2 was 300 s and cathode potential was −0.8 V. Performance influenced by the exogenous factors (e.g., initial pH and coexisted ions) were further investigated. It was found that the neutral pH was the most favorable for ECH and a reduction in dechlorination efficiency (6% ∼ 47.6%) was observed in presence of 5 mmol/L of NO 2 − , NO 3 − , S2− or SO 3 2 − . Cyclic voltammetry (CV) and quenching experiments verified the existence of three hydrogen species on Pd surface, including adsorbed atomic hydrogen (H*ads), absorbed atomic hydrogen (H*abs), and molecular hydrogen (H2). And the introduction of MnO2 promoted the generation of atomic H*. Only adsorbed atomic hydrogen (H*ads) was confirmed that it truly facilitated the ECH process. Besides H*ads induced reduction, the direct reduction by cathode electrons also participated in the 2,4,6-TCP dechlorination process. Pd/MnO2/Ni foam cathode shows excellent dechlorination performance, fine stability and recyclable potential, which provides strategies for the effective degradation of persistent halogenated organic pollutants in groundwater.

Due to its high theoretical capacity and appropriate potential platform, tin-based alloy materials are expected to be a competitive candidate for the next-generation high performance anodes of lithium-ion batteries. Nevertheless, the immense volume change during the lithium-ion insert process leads to severe disadvantages of structural damage and capacity fade, which limits its practical application. In this work, a three-dimensional (3D) multicore-shell hollow nanobox encapsulated by carbon layer is obtained via a three-step method of hydrothermal reaction, annealing and alkali etching. During the electrochemical reactions, the CoSn@void@C nanoboxes provide internal space to compensate the volumetric change upon the lithiation of Sn, while the inactive component of Co acts as chemical buffers to withstand the anisotropic expansion of nanoparticles. Owing to the above-mentioned advantages, the elaborated anode delivers an excellent capacity of 788.2 mAh/g at 100 mA/g after 100 cycles and considerable capacity retention of 519.2 mAh/g even at a high current density of 1 A/g after 300 cycles. The superior stability and high performance indicate its capability as promising anodes for lithium-ion batteries.

Lithium–sulfur (Li–S) battery is labeled as a promising high-energy-density battery system, but some inherent drawbacks of sulfur cathode materials using relatively complicated techniques impair the practical applications. Herein, an integrated approach is proposed to fabricate the high-performance rGO/VS4/S cathode composites through a simple one-step solvothermal method, where nano sulfur and VS4 particles are uniformly distributed on the conductive rGO matrix. rGO and sulfiphilic VS4 provide electron transfer skeleton and physical/chemical anchor for soluble lithium polysulfides (LiPS). Meanwhile, VS4 could also act as an electrochemical mediator to efficiently enhance the utilization and reversible conversion of LiPS. Correspondingly, the rGO/VS4/S composites maintain a high reversible capacity of 969 mAh/g at 0.2 C after 100 cycles, with a capacity retention rate of 82.3%. The capacity fade rate could lower to 0.0374% per cycle at 1 C. Moreover, capacity still sustains 795 mAh g–1 after 100 cycles in the relatively high-sulfur-loading battery (6.5 mg/cm2). Thus, the suggested method in configuring the sulfur-based composites is demonstrated a simple and efficient strategy to construct the high-performance Li–S batteries.

Self-supported transition-metal single-atom catalysts (SACs) facilitate the industrialization of electrochemical CO2 reduction, but suffer from high structural heterogeneity with limited catalytic selectivity. Here we present a facile and scalable approach for the synthesis of self-supported nickel@nitrogen-doped carbon nanotubes grown on carbon nanofiber membrane (Ni@NCNTs/CFM), where the Ni single atoms and nanoparticles (NPs) are anchored on the wall and inside of nitrogen-doped carbon nanotubes respectively. The side effect of Ni NPs was further effectively inhibited by alloying Ni with Cu atoms to alter their d-band center, which is theoretically predicted and experimentally proved. The optimal catalyst Ni9Cu1@NCNTs/CFM exhibits an ultrahigh CO Faradic efficiency over 97% at −0.7 V versus reversible hydrogen electrode. Additionally, this catalyst shows excellent mechanical strength which can be directly used as a self-supporting catalyst for Zn-CO2 battery with a peak power density of ∼0.65 mW/cm2 at 2.25 mA/cm2 and a long-term stability for 150 cycles. This work opens up a general avenue to facilely prepare self-supported SACs with unitary single-atom site for CO2 utilization.

Electrochemical catalysts for the hydrogen evolution reaction (HER) have attracted increasing attentions. Noble metal-free cocatalysts play a vital role in HER applications. Herein, a novel strategy to prepare a Ni2P/MoS2 cocatalyst through a simple hydrothermal-phosphorization method was reported, and the prepared cocatalyst was then loaded on an N-doped carbon substrate with excellent conductive performance. The large surface area of the carbon substrate provided many active sites, and the interface between Ni2P and MoS2 improved the catalytic performance for the HER. Compared with pure Ni2P catalyst and MoS2 catalyst, the prepared Ni2P/MoS2 cocatalyst exhibited enhanced catalytic performance. In addition, the results indicate that the prepared cocatalyst has a wide pH range and low onset potential values of 280, 350 and 40 mV in acidic, phosphate-buffered saline and alkaline solutions, respectively, and the corresponding Tafel slopes are 75, 121 and 95 mV dec−1, respectively. Density functional theory (DFT) was adopted to calculate the hydrogen adsorption free energy (△GH∗). The results showed that the interface between Ni2P and MoS2 reduced △GH∗, which was beneficial to the adsorption of hydrogen. Present preparation of cocatalysts with unique interfaces provides a new strategy for improving the catalytic performance of HER.

The lithium dendrite growth is still a serious challenge and impeding the realistic applications of all-solid-state lithium batteries. In view of the amide containing sediment layer can be stable on lithium/cathodes, a composite polymer electrolyte with amide-based matrix is in-situ built on porous electrodes. With the introduction of amide, the polymer electrolyte presents excellent ability to inhibit lithium dendrite growth and makes the Li/Li symmetric battery stably work for 500 hours with a good ionic conductivity of 4.25 × 10−5 S/cm at 40 °C. The solid electrolyte also shows a wide electrochemical stable window and good interface contact with the porous cathode. Utilizing this composite polymer electrolyte, the all-solid-state Li/LiFePO4 battery shows an initial discharge capacity of 146.5 mAh/g at 0.1 C under 40 oC and remains 81.4% in 100 cycles. The polymer electrolyte also can present better properties after modification. These results demonstrate that the presented PA-based composite polymer electrolyte could be served as a good electrolyte candidate for all-solid-state lithium-ion batteries.

Microalgae based biophotovoltaic (BPV) cells are substantiated as innovative renewable energy generation devices, owing to their ability in mimicking the catalytic activity of microorganisms for water splitting reaction along with an effectual reduction of carbon footprint in our environment. As the direct contact between algal cells and anodic surface effectually governs the electron transfer and overall BPV performance, the development of electrochemically active and stable catalysts is crucial for the evolution of high performance BPVs. Accordingly, the monoclinic structured copper (Cu) metal organic framework (MOF) is prepared through the simple ageing process and the consequent bimetallic (Cu-Nickel(Ni)) MOF is developed via the partial substitution of Cu2+ with Ni2+ nodes without any variation in the chemical structure of Cu-MOF. The as-formulated MOFs loaded indium tin oxides (ITOs) are exploited as BPV anodes and their influences on green energy generation by using the freshwater microalgae Chlorella sp. UMACC 313 as a catalytic system are scrutinized in detail. The electrochemical activeness and robust stability of as-fabricated BPV anodes are enunciated, respectively, from the cyclic voltammetry and chronoamperometry techniques. Cu-Ni MOF/ITO equipped BPV establishes the power density of 40 μWm−2, which is substantially higher than those of Cu-MOF/ITO and ITO. The substantial features of Cu-Ni MOF including the elevated structural integrity, existence of different metallic ions with the rational electrical conductivity, and supplemental functionality accelerate its maximum green energy generation performance. Thus, these verdicts establish a distinctive approach in tailoring the electrochemically active and stable MOF anode materials for the evolution of ecologically benevolent fuel cells.

Electrochemical storage of neutralised protons in porous carbon materials such as activated carbons and multi-layer graphene is becoming possible using novel technologies such as the proton battery and proton flow reactor. This set-up is a promising option for electrical energy storage at various scales, and possibly for exporting a zero-emission hydrogen-based fuel. This paper focusses on understanding and identifying the contributions to hydrogen storage in activated carbon from phenolic resin (aC PR) from processes such as electric double layer capacitance, electrosorption, cationic concentration by intercalation in ultramicropores, and reversible faradaic (redox) reactions between hydronium, and negatively-charged carbon surfaces inside pores with and without intermediary oxygen groups. A combination of XPS, Raman, and infrared spectroscopy is employed to identify the forms of C ⋯ H reactions involved, together with temperature programmed desorption, cyclic voltammetry and galvanostatic charging and discharging. Experimental evidence for the formation of C⋯H bonding in aC PR is presented, which promises to be sufficient for use of this and similar carbon materials as a solid-state hydrogen storage material with competitive energy density.

The production of hydrogen as a clean energy source by a facile method are major concern and promising research area now a days. The electrolysis of water to generate hydrogen and oxygen as a fuel are challenging renewable energy technology. To develop a highly efficient low-cost non-noble metal-based catalyst for hydrogen evolution reaction (HER) is essential and urgent need. Thus, the present work describes a facile synthetic approach to develop suitable cost effective electrocatalyst for water splitting application. It deals one-pot synthesis of low-cost transition metal based ternary metal sulphide (BMS) CuCo2S4, CuMn2S4, CuNi2S4, and CuZn2S4 microspheres as electrocatalyst to generate hydrogen from water. The physical characterization of synthesized electrocatalyst were performed by powder x-ray diffractometer (PXRD) and Raman spectroscopy. The morphological characterization of synthesized electrocatalyst were done by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) however the elemental mapping analysis was done by energy-dispersive X-ray spectroscopy (EDX). The electrochemical measurements were performed in 0.5 M H2SO4 acidic medium on 3-electrode polymer electrolyser membrane water (PEMW) system. The lowest onset and overpotential values have been observed as 61 and 79 mV, respectively in the case of CuCo2S4 micro-sphere. However, the Tafel slope values of CuCo2S4, CuMn2S4, CuNi2S4, and CuZn2S4 electrocatalysts were calculated 121, 115, 102 and 41 mV respectively. On the basis of obtained electrochemical characterization results, CuCo2S4 has been revealed better electrocatalyst under acidic media. This study opens a new direction to consider low-cost transition metal based ternary microspheres as electrocatalyst to produce hydrogen during water electrolysis.

Fe-N-C structures have been considered as a candidate to replace noble metal catalysts towards oxygen reduction reaction (ORR) due to their excellent electrocatalytic activity and durability. Herein, a zinc-mediated synthesis strategy is proposed for N-doped graphitic porous carbon encapsulated uniform dispersed Fe3C nanoparticles coupled with atomically dispersed Fe-Nx moieties (NPC/Fe-N-C) derived from biomass coconut shell. The introduction of zinc species could be conductive to the dispersion of iron species and formation of porous structures. Density functional theory calculations demonstrate that the N-doped carbon coating structures can weaken the oxygen intermediates adsorption energy barrier of Fe3C. Besides, the graphitic carbon could promote the electron transfer during the electrochemical reaction. These special structures enable NPC/Fe-N-C to have excellent ORR activity with an Eonset of 1.0 V, which is much better than Pt/C. Furthermore, the zinc-air battery assembled by pairing NPC/Fe-N-C with a high-efficiency oxygen evolution reaction (OER) catalyst can continuously and stably operate a charge-discharge potential gap of 0.8 V at 10 mA/cm2 for more than 600 hours. More importantly, the assembled batteries could drive overall water splitting device, realizing the effective energy conversion.

The oxidation of anode carbon fuel directly affects the electrochemical performance of molten hydroxide direct carbon fuel cell (MHDCFC). In general, the anode carbon fuel can be oxidized at higher temperature, thus the direct carbon fuel cell (DCFC) can show a great electrochemical performance. In this study, rare earth oxide (La2O3, CeO2, Pr6O11) were prepared by the method of precipitation. Activated carbon was prepared by pretreatment of lignite. Rare earth oxide and activated carbon were mixed as anode carbon fuel, and rare earth oxide were used to catalyze the electrochemical oxidation of anode carbon fuel. The results show that CeO2 has better electrocatalytic activity compared with La2O3 and Pr6O11 in the MHDCFC. The electrochemical test results show that the current density (at 0.4V) increases from 81.02 to 112.90 mA/cm2 and the maximum power density increases from 34.78 to 47.05 mW/cm2 at 450 °C, when the mass fraction of CeO2 is increased from 0 to 40%. When the mass fraction of CeO2 is 30%, the current density (82.55 mA/cm2 at 0.4V) at 400 °C is higher than that (81.02 mA/cm2 at 0.4V) without CeO2 at 450 °C. The electrochemical oxidation mechanism of CeO2 catalyzed anode carbon fuel is discussed.

Hybrid CuO-Co3O4 nanosphere building blocks have been embedded between the layered nanosheets of reduced graphene oxides with a 3D hybrid architecture (CuO-Co3O4-RGO), which are successfully applied as enhanced anodes for lithium-ion batteries (LIBs). The CuO-Co3O4-RGO sandwiched nanostructures exhibit a reversible capacity of ∼847 mA·h·g−1 after 200 cycles’ cycling at 100 mA·g−1 with a capacity retention of 79%. The CuO-Co3O4-RGO compounds show superior electrochemical properties than the comparative CuO-Co3O4, Co3O4 and CuO anodes, which may be ascribed to the following reasons: the hybridizing multicomponent can probably give the complementary advantages; the mutual benefit of uniformly distributing nanospheres across the layered RGO nanosheets can avoid the agglomeration of both the RGO nanosheets and the CuO-Co3O4 nanospheres; the three dimensional (3D) storage structure as well as the graphene wrapped composite could enhance the electrical conductivity and reduce volume expansion effect associated with the discharge-charge process.

Electrochemical nitrate reduction reaction (NO3−RR) is an ideal route to produce ammonia (NH3) under ambient conditions. Although a markedly improved NH3 production rate has been achieved on the NO...

Ambient electrochemical nitrogen fixation is a promising and environmentally benign route for producing sustainable ammonia, but has been limited by the poor performance of existing catalysts that ...

As the most commonly used antipyretic and analgesic drug, paracetamol (PA) coexists with neurotransmitter dopamine (DA) in real biological samples. Their simultaneous determination is extremely important for human health, but puzzled by their mutual interference. In order to improve the conductivity, adsorption affinity, sensitivity and selectivity of TiO2-based electrochemical sensor, N-doped carbon@TiO2 double-shelled hollow sphere (H–C/N@TiO2) is designed and synthesized by simple alcoholic and hydrothermal method, using polystyrene sphere (PS) as a template. Meanwhile, TiO2 hollow spheres (H–TiO2) or N-doped carbon hollow spheres (H–C/N) are prepared by the same method. H–C/N@TiO2 hollow spheres have good conductivity, charge separation, and the highly enhanced and stable current responses for the detection of PA and DA. The detection limit and linear range are 50.0 nmol/L and 0.3–50 μmol/L for PA, 40.0 nmol/L and 0.3–50 μmol/L for DA, respectively, which are better than those of carbon-based sensors. Moreover, this electrochemical sensor with high selectivity, strong anti-interference, high reliability, and long time durability, can be used for the simultaneous detection of PA and DA in human blood serum and saliva. The high electrochemical performance of H–C/N@TiO2 is attributed to the multi-functional combination of different layers, because of good conductivity, absorption and electrons transfer ability from in-situ N-doped carbon and electrocatalytic activity from TiO2.

CO2 electroreduction reaction (CO2RR) has been considered as an effective technology to close the anthropogenic carbon cycle. Formate, a product of two-electron transfer in CO2RR, is an economically valuable feedstock. In this work, nanoporous tin oxides were controllable synthesized by a facile and scalable electrochemical anodic oxidation method. XPS result indicated that the increased Sn4+ species after anodic oxidation were beneficial to reduce the overpotential of formate formation. Operando Raman spectra revealed that the enhanced formate selectivity could be attributed to the high local pH within the porous structure, which suppresses hydrogen evolution reaction (competing reaction against CO2RR). Further flow cell test showed a formate partial current density of 285 mA·cm−2 with the selectivity of 96.4%, indicating a promising industrial application prospect.

Transition metal selenides attract significant attention as advanced anode materials for sodium-ion batteries (SIBs) in recent years due to their appropriate working potential and high theoretic capacity. However, the poor structural stability and rate capability limit their further practical applications. Herein, zeolite imidazole framework-8/zeolite imidazole framework-67 is used as a template to prepare Co0.85Se and ZnSe nanoparticles embed in N-doped carbon matrix successfully, and then coated a carbon layer (ZCS@NC@C) by in-situ polymerization. One side, the N-doped carbon matrix with rich pore structure not only shorten the diffusion path of Na+ and improve the conductivity of the electrode, but also prevent structural collapse and agglomeration of active particles during the sodium insertion/extraction process. On the other side, the carbon shell preparation by coating can form a protective layer to buffer the volumetric stress generated in the electrochemical process and further improve the electrical conductivity. As a result, the as-prepared ZCS@NC@C anode material exhibits an excellent electrochemical performance for SIBs. This investigation provides a promising approach to optimize the electrochemical performance of SIBs by incorporating active metal compounds into conductive carbons to form multidimensional structure.

Well-defined two-dimensional (2D) cobalt oxalate (CoC2O4•2H2O) nanosheets exhibit more excellent property than common bulk cobalt oxalate due to high specific surface areas and high-efficient transport of ion and electron. However, the delicate control of the 2D morphology of CoC2O4•2H2O during their synthesis remains challenging. Herein, 2D CoC2O4•2H2O nanosheets (M1), grown by straightforward chemical precipitation, can be tuned from three-dimensional (3D) structure during their synthesis with no templates or capping agents. This control is obtained by rationally changing the ratio of reactants with ethylene glycol as solvent. Moreover, Co3O4/CoC2O4 composites (M1-250) have been fabricated through low-temperature thermal treatment of the M1 precursor in air, which possess porous surfaces with the 2D morphology maintained. Benefiting from the porous surfaces, more redox-active sites and better electrical conductivity of Co3O4, the constructed M1-250//AC aqueous device manifest improved kinetics of the electrochemistry process with energy density of 27.9 Wh/kg at 550.7 W/kg and good cycling stability with sustaining 73.0 mAh/g after 5000 cycles.

All-solid-state lithium batteries (ASSLBs), receiving extensive attentions and studies, exhibit better safety, environmental friendliness, stability, wider electrochemical stability window and higher energy density than traditionally liquid lithium batteries. In a variety of inorganic materials, with highly replaceable, the non-lithium metal elements emerge in endlessly and affect performances in diversiform ways. Due to facile preparation, convertible structures and excellent properties, the lithium-containing bimetallic granular materials are often applied as important components of electrolytes in lithium batteries. In this review, in terms of the properties of substituted elements, changing crystal structures, increasing vacancies or defects and improving the interfacial conductions, the roles of metal element substitutions of inorganic particles on the improvement of solid-state electrolytes are expounded. And the applications of substituted strategies in ASSLBs as the host of inorganic particles electrolytes and as fillers or modifications for composite electrolytes are also investigated and discussed. It also summarizes the current concerns and obstacles that need to be broken through, as well as provides a basis guide for the selection and optimization of inorganic particles.

Rutin, a flavonoid found in fruits and vegetables, is a potential anticancer compound with strong anticancer activity. Therefore, electrochemical sensor was developed for the detection of rutin. In this study, CoWO4 nanosheets were synthesized via a hydrothermal method, and porous carbon (PC) was prepared via high-temperature pyrolysis. Successful preparation of the materials was confirmed, and characterization was performed by transmission electron microscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy. A mixture of PC and CoWO4 nanosheets was used as an electrode modifier to fabricate the electrochemical sensor for the electrochemical determination of rutin. The 3D CoWO4 nanosheets exhibited high electrocatalytic activity and good stability. PC has a high surface-to-volume ratio and superior conductivity. Moreover, the hydrophobicity of PC allows large amounts of rutin to be adsorbed, there by increasing the concentration of rutin at the electrode surface. Owing to the synergistic effect of the 3D CoWO4 nanosheets and PC, the developed electrochemical sensor was employed to quantitively determine rutin with high stability and sensitivity. The sensor showed a good linear range (5–5000 ng/mL) with a detection limit of 0.45 ng/mL. The developed sensor was successfully applied to the determination of rutin in crushed tablets and human serum samples.

Two-dimensional (2D) materials have exhibited great potential for replacing costly Pt for oxygen reduction reaction (ORR) because of their distinctive structural features and high pre-site activity. However, their performance is generally hindered by the limited density of active sites (e.g., at the layer edges). Although they feature a high exposure of surface sites, these sites are typically inert for ORR. Herein, through density functional theory calculations, we propose a promising ORR catalyst candidate, a 2D TaTe2 nanosheet, which has an intrinsic high basal-plane activity. Both of the thermodynamic and kinetic processes are explored, which demonstrates that the basal-plane Te sites of the TaTe2 nanosheet have great potential for facilitating ORR. Specifically, we construct a microkinetic model of ORR proceeding on TaTe2, which unveils its dynamic intermediate coverage under different electrode potentials and identifies the dominating associative pathway. The theoretical half-wave potential of TaTe2 is predicted to be 0.87 V, which exceeds those of the well-established Pt (111) and Fe–N–C single-atom catalysts computed at the same level. This study not only presents the first 2D, non-Pt ORR catalyst candidate with an intrinsic basal-plane activity but also offers a rational methodology for unveiling the mechanism/activity of ORR and other electrochemical reactions.

Tailor-made advanced electrocatalysts with high active and stable for hydrogen evolution reaction (HER) play a key role in the development of hydrogen economy. Herein, a N,P-co-doped molybdenum carbide confined in porous carbon matrix (N,P-Mo2C/NPC) with a hierarchical structure is prepared by a resources recovery process. The N,P-Mo2C/NPC compound exhibits outstanding HER activity with a low overpotential of 84 mV to achieve 10 mA/cm2, and excellent stability in alkaline media. The electrochemical measurements confirm that the enhanced HER activity of N,P-Mo2C/NPC is ascribe to the synergy of N,P-codoped and porous carbon matrix. Density functional theory calculations further reveal that the electron density of active sites on Mo2C can be regulated by the N/P doping, leading to optimal H adsorption strength. In this work, the proof-of-concept resource utilization, a microorganism derived molybdenum carbide electrocatalyst for HER is fabricated, which may inaugurate a new way for designing electrocatalysts by the utilization of solid waste.

The selection and development of cathode of alkaline zinc batteries (AZBs) is still hindered and often leads to poor rate capability and short cycle life. Here, amorphous hollow nickel-cobalt-based sulfides nanocages with nanosheet arrays (AM-NCS) are designed and constructed with ZIF-67 as the self-template to exchange with Ni2+ and S2− by using a two-step ion exchange method. The synthesized AM-NCS possess the high specific capacity (160 mAh/g at 2 A/g), and the assembled battery has excellent rate performance (146 mAh/g reversible capacity at 5 A/g). The assembled device has excellent rate performance (155 mAh/g at 2 A/g) and long cycling stability (7000 cycles, 62.5% of initial capacity). The excellent electrochemical properties of the electrode materials are mainly attributed to the unique structure, in particular, polyhedron structure with hollow structure can improve the cyclic stability, and the amorphous structure can expose more reactive sites on the surfaces of nickel, cobalt and sulfur. This work provides a new strategy for the design and fabrication of high performance cathode materials for AZBs.

3D electrodes have shown extraordinary promise for electrochemical energy storage devices in wearable electronics. However, it is still a significant challenge to rationally design 3D electrode that has the characteristics of lightweight, flexibility, low cost, high performance and miniaturization. In this work, we present a novel design of 3D electrode by directly growing the nanocrystalline TiO2 film on carbonized eggshell membrane. The unique architecture can supply not only a continuous electron transport pathway through an interconnected carbon fibrous network but also an efficient electrolyte flux via an interpenetrating porous network. Besides, nanocrystalline TiO2 film on carbonized eggshell membrane offers a short ion diffusion path in the solid-phase, leading to a rapid kinetic of electrochemical reaction. When tested as an anode for Li-ion battery, TiO2 film in 3D electrode demonstrated excellent electrochemical performance with a large reversible capacity, excellent rate capacity and long life cycling property.

NASICON-type Na3V2(PO4)3 is a promising electrode material for developing advanced sodium-ion batteries. Preparing Na3V2(PO4)3 with good performance by a cost-effective and large-scale method is significant for industrial applications. In this work, a porous Na3V2(PO4)3/C cathode material with excellent electrochemical performance is successfully prepared by an agar-gel combined with freeze-drying method. The Na3V2(PO4)3/C cathode displayed specific capacities of 113.4 mAh·g−1, 107.0 mAh·g−1 and 87.1 mAh·g−1 at 0.1 C, 1 C and 10 C, respectively. For the first time, the 500-mAh soft-packed symmetrical sodium-ion batteries based on Na3V2(PO4)3/C electrodes are successfully fabricated. The 500-mAh symmetrical batteries exhibit outstanding low temperature performance with a capacity retention of 83% at 0 °C owing to the rapid sodium ion migration ability and structural stability of Na3V2(PO4)3/C. Moreover, the thermal runaway features are revealed by accelerating rate calorimetry (ARC) test for the first time. Thermal stability and safety of the symmetrical batteries are demonstrated to be better than lithium-ion batteries and some reported sodium-ion batteries. Our work makes it clear that the soft-packed symmetrical sodium ion batteries based on Na3V2(PO4)3/C have a prospect of practical application in high safety requirement fields.

Tellurium (Te) is an ideal electrode for potassium ion batteries (PIBs) owing to its excellent electronic conductivity and high volumetric capacity. However, the Te electrode is prone to capacity fading as the shuttle effect. To address this challenge, we propose molecular regulated Se–Te solid solutions on N-doped porous carbon as the PIBs electrode. After optimizing the Se content in Se–Te solid solutions, the resultant SeTe6.8 on N-doped porous carbon (SeTe6.8@C) delivered a capacity of over 400 mAh g−1 with a flat plateau of 1.0 V at 500 mA g−1. It also achieved a superiorly long cycle life, running for more than 1600 cycles (over 7 months with 0.015% degeneration per cycle) at 100 mA g−1 and excellent rate performance (179.9 mAh g−1 at 10000 mA g−1). This remarkable electrochemical energy storage of the Te electorde likely arises from suppression of the shuttle effect after doping the Te with strongly electronegative Se atoms (forming K5Te3 which is not easily soluble in electrolyte). This study presents a fresh approach for designing and developing ultra-stable Te-based electrodes for PIBs and beyond.

Background: Yttria stabilized zirconia (YSZ) is an attractive material which exhibits a characteristic combination of physical and chemical properties of YSZ in terms of inertness, resistant to corrosion, high mechanical strength, thermal stability, chemical stability and photostability. Because of these properties and applications, it is very important to synthesize yttrium stabilized zirconia (YSZ) powder. Till date, various preparative techniques have been reported for the synthesis of high porous YSZ nano powders. However, special equipment, long time with multistep processing, high calcination temperature, small surface area and low product yield are the usual drawbacks of most of the methods. Therefore. Solution combustion method (SCS) method has been established for the synthesis of YSZ nanopowder with high surface area. Objective: The main objective of our present research work is to effectively synthesized the Yttrium stabilized zirconia (YSZ) Zr0.72 Y0.28 O1.862 nanopowder by solution combustion method using yttrium nitrate (Y(NO3)3.6H2O), zirconyl nitrate (ZrO(NO3)2.XH3O) as oxidizers and ethylenediamine tetra acetic acid (EDTA) as a fuel and the synthesized powder was used in the application of photodegradation of dyes. Methods: YSZ nanopowder was synthesized by using Solution combustion synthesis. Solution combustion synthesis (SCS) is a simple exothermic self-sustaining one step chemical reaction, which will produce a large number of pores in the oxide material and inhibit their agglomeration leading to a large specific surface area and small crystallite size of the resulting material. Results and Discussion: Powder X-ray diffraction (PXRD) revealed the formation of pure cubic phase of YSZ (Zr0.72 Y0.28 O1.862) nanopowder and the crystallite size of 15.4 nm was calculated by using Scherrer’s formula. The porous morphology of the product was observed by SEM images. BET surface area reveals that the relatively larger surface area of 87.17 m2g-1. TEM analysis revealed uniform particle size distribution with average particle sizes varying in the range of 20-100 nm. The UV-Vis DRS spectrum was used to calculate the absorption wavelength (339 nm) and the corresponding band gap (3.72 eV) using Tauc plot. The photoluminescence spectrum of YSZ nanopowder showed an emission peak at 339 nm. The photodegradation (decolourisation) of methylene blue (MB) dye was increased from 75-90% with increase in the concentration of YSZ photocatalyst from 100 mg to 400 mg due to availability of OH radicals in the presence of UV radiation. The electrochemical studies using cyclic voltammetry reveal a substantial increase in current density of YSZ electrode from 0.0001A to 0.0005A when compared with bare carbon electrode and the instantaneous rise in redox current for the YSZ electrodes from 0.0001A to 0.0005A with increasing scan rate from 10 mVs-1 to 90 mVs-1. Conclusion: In our reported work, we start a simple and rapid solution combustion synthetic approach to produce highly effective YSZ nanopowder using EDTA as organic fuel. Because of large surface area and small particle size of the YSZ nanopowder shows 85% of degradation of MB takes place in presence of UV light. In order to understand the electrochemical property of YSZ, the redox current measurement was carried out using cyclic voltametry and resulted that increase in redox current for the YSZ electrodes with increasing scan rate from 10 mVs-1 to 90 mVs-1.

This work shows the technical feasibility to obtain uranium tetrafluoride through an electrochemical mercury cell. This technique represents a custom scaling-up methodology from our previous studies to obtain UF4 using the dropping mercury electrode cell. The UF4 products were obtained from natural UF6 gas, which was hydrolyzed to obtain a 50 g/L UO2F2 solution. The electrolysis cell was made using a mercury reservoir, to reach UF4 production rates of 1 Kg UF4/day. This custom design allowed a stable UF4 production thanks to the mercury cathode, which do not permit the accumulation of solid products in its surface. The cell was tested using current densities from 5.000 to 17.500 A/m2 and temperatures from 25 to 65 °C. The maximum current efficiency achieved under these conditions was 80%. The UF4 powders possessed spherical morphology, with diameters between 20 – 80 μm. Compared to the SnCl2 precipitation, this process did not allow preferential growth of the precipitates. This improved the compaction of the UF4 – Mg powders mixtures, with densities between 3.0 – 3.5 g/cm3. The purity of the UF4 products was over 98%.