The design and development of low-cost, abundant reserves, high catalytic activity and durability bifunctional electrocatalysts for water splitting are of great significance. Here, simple ...hydrothermal and hydrogen reduction methods were used to fabricate a uniform distribution of Fe-doped MoO2/MoO3 sheets with abundant oxygen vacancies and heterojunctions on etched nickel foam (ENF). The Fe– MoO2/MoO3/ENF exhibited a small overpotential of 36 mV at 10 mA cm−2 for hydrogen evolution reaction (HER), an excellent oxygen evolution reaction (OER) overpotential of 310 mV at 100 mA cm−2 and outstanding stabilities of 95 h and 120 h for the HER and OER, respectively. As both cathode and anode catalysts, the heterogeneously structured Fe– MoO2/MoO3/ENF required a low cell voltage of 1.57 V at 10 mA cm−2. Density functional theory (DFT) calculations show that Fe doping and MoO2/MoO3 heterojunctions can significantly reduce the band gap of the electrode, accelerate electron transport and reduce the potential barrier for water splitting. This work provides a new approach for designing metal ion doping and heterostructure formation that may be adapted to transition metal oxides for water splitting.
Display omitted
•Improve the adhesion of the materials by etching nickel foam (NF).•Two-step reaction simultaneously achieves iron doping and heterojunctions.•DFT calculations confirm that Fe doping increased the conductivity.•In situ grown heterojunctions greatly reduce the potential barrier.
The global movement of people and goods has increased the risk of biosecurity threats and their potential to induce large economic, social, and environmental harm. Integration of biosafety monitoring ...networks has become a top priority for addressing biosafety issues. In order to resolve the data standards and integration problems in the field of biosafety in China, the Biosafety Surveillance Conceptual Data Model (BSCDM), which is an object-oriented, hierarchically designed, flexible and scalable biosafety surveillance concept data model, is proposed in this article. This model is based on the integration of business process management and data resources of disease surveillance, animal disease surveillance and potential invasive biological monitoring. In reference to the Public Health Conceptual Data Model (PHCDM) and Federal Enterprise Architecture (FEA), BSCDM conducts a thorough analysis of biosafety monitoring activities, records basic information requirements of biosafety monitoring and provides data set standards for biosafety-related activities. It is developed with the Unified Modeling Language (UML) and could be applied as an open standard for accelerating data analysis and promoting collaboration. This study attempts to integrate biosafety monitoring data and the presented model has been tested in the detection of dengue fever in China and will be applied to other biosafety fields.
Scientific question.∙In China, to establish and integrate biosafety monitoring networks and to formulate data standards have become a top priority for addressing the diverse biological threats.Evidence before this study.∙Several biosafety networks and integration systems have been developed and are using worldwidely. However, in China, the current biosafety monitoring systems and management system are still lack of effective communication and interaction.New Findings.∙Here we proposed an object-oriented, hierarchically designed, flexible and scalable biosafety surveillance concept data model, which guides conduction of a thorough analysis of biosafety activities, records basic information requirements for biosafety monitoring, and provides data set standards for biosafety-related activities.Significance of the study.∙In this study, we provided a new conceptual data model, Biosafety Surveillance Conceptual Data Model (BSCDM), to integrate biosafety surveillance data. This model has been used in the detection of dengue fever in China and will be applied to man other biosafety fields.
Fabricating low-overpotential materials for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is an important component of current developments in clean energy. Here, we use ...nickel oxide for its high hydrophilicity and ammonium fluoride to cause the current collector to produce more active sites with increased adhesion to prepare 2D ultrafine Mo-based precursor nanosheets with uniform dimensions and a stable structure on nickel foam (NF). Further phosphorization treatment is performed to obtain porous molybdenum phosphide (MoP) nanosheets on Ni3P/NF. As a freestanding integrated electrode, MoP@Ni3P/NF possess excellent catalytic activity for the HER and OER with low overpotentials (45 mV to reach 10 mA cm−2 for the HER and 331 mV to reach 35 mA cm−2 for the OER). The performance of this catalyst is close to that of some precious metal catalysts. The activity as both an anode and cathode catalyst for overall water splitting can reach 1.67 V at 10 mA cm−2. Due to its scalable preparation and stability, the MoP@Ni3P/NF electrocatalyst is promising for use in practical water-alkali electrolysis.
•The nucleation sites of nickel foam have been significantly increased by calcination.•The MoP@Ni3P/NF exhibits extraordinary catalytic activity for the HER and OER with low overpotentials.•The HER performance of this catalyst exceeds that of most MoP materials.
Electrochemical N2 reduction reaction (NRR) has received much attention in recent times. Aiming for, discovering potential electrocatalysts with superior activity, stability and selectivity, a series ...of 3 d transition metal dimers were studied by density functional theory (DFT) calculations. The investigation reveals that most of the metal dimers have admirable stability, and partial density of states (PDOS) confirms that the unoccupied and occupied d orbitals of metal atoms are the key for effective activation of N2. Especially, two metal dimers bonded to nitrogen-doped graphene, FeFe and CoCo, can selectively adsorb and activate N2 for efficient conversion. Their limiting potentials are −0.44 and −0.45 V, which are superior than to most of the catalysts and they can well suppress the hydrogen evolution reaction (HER). Moreover, the desorption free energy of NH3 is 0.54 and 0.57 eV respectively for FeFe and CoCo, guarantees the good durability of the catalysts.
•Electronic structure analysis shows that metal atoms are the key to activating N2.•The strong adsorption of N2 does not imply good electrocatalytic activity.•FeFe and CoCo dimers can capture N2 selectively and activate N2 effectively.•FeFe and CoCo dimers have catalytic activity and good NH3 desorption ability.
Silicon nanowires are a kind of promising negative electrode material for lithium-ion batteries. However, the existing production technologies can hardly meet the demands of silicon nanowires in ...quality and production ability. In this paper, silicon nanowires are successfully prepared by molten salt electrolysis in a pilot-plant. The pilot-plant was successfully operated for 14 months with a current efficiency of 80.3% and an electrolysis energy consumption of 12.8 kW h/kg-Si. The obtained silicon nanowires as a negative electrode material show a specific discharge capacity of 3095 mA h/g and a coulombic efficiency of 89.7% in the first charge–discharge cycle at a rate of 0.1 C in coin-type cell tests and a capacity retention of 83.4% after 250 cycles at a rate of 1 C in pouch cell tests when mixed with graphite.
•WO3-RE (RE=Ce, Eu, Sm, Gd) nanofilms were prepared using one-step hydrothermal.•WO3-RE exhibited high optical contrast, fast switching speed, and excellent stability.•The optical contrast of WO3-Sm ...nanofilm was greater than 68.3% in the 500–1100 nm range.•The areal capacitance of the WO3 film were increased by around 351% by doping Sm ions.
Electrochromic capacitors are attracting a huge attention due to their dual functions in energy-saving and energy storage. Electrochromic and energy storage performance of the films could be effectively improved through regulating their physical phase and morphology. In the present work, the physical phase and morphology of the WO3 nanofilms were regulated by doping RE ions (RE = Ce, Eu, Sm, Gd) using one-step hydrothermal technology. The three-dimensional (3D) urchin-like crystal WO3 nanofilm would transfer into the 3D nest-like WO3 (WO3-RE) nanofilms that consisted of crystal and amorphous phase by doping RE ions. Compared with the pure WO3 nanofilm, the WO3-RE nanofilms exhibited higher optical contrast, faster switching speed, longer cyclic stability, and larger areal capacitance owing to faster ions transfer rate and more stable film structure. The optical contrast of WO3-Eu and WO3-Sm nanofilms were 76.3% and 73.8% at 633 nm, 75.5% and 74.6% at 900 nm wavelength, respectively. Notably, the WO3-Eu and WO3-Sm nanofilms could retain 99.6% and 99.1% of their original optical contrasts after 1000 cycles, respectively. Additionally, the areal capacitance of ECDs based on the WO3/PB, WO3-Ce/PB, WO3-Eu/PB, WO3-Sm/PB, and WO3-Gd/PB were 26.15, 49.27, 58.23, 71.46, and 79.52 mF/cm2 at 0.3 mA/cm2, respectively. ECDs based on the WO3-RE/PB are promising for energy-saving and energy storage dual functional smart windows.
Display omitted .
Display omitted
•PW-x (x = 2, 3, 4) films were prepared using free-seed layer hydrothermal technology.•PW-2 exhibited high optical contrast, high coloration efficiency, and excellent stability.•The ...optical contrasts of PW-2 film was greater than 62.8% in the 600–1100 nm range.•PW-2 film still remained as 90.8% of its original optical contrast after 5000 cycles.
Constructing a nanostructured electrochromic film and enhancing the bonding strength between the electrochromic film and electrode would effectively improve the charge transport and stability of the electrochromic film. In the present study, nanoporous WO3 films, including WO3 films without polydopamine (W-x, x = 2, 3, and 4) and WO3 films with polydopamine (PW-x, x = 2, 3, and 4), were built using a low-temperature hydrothermal method. The PW-x films showed significantly improved electrochromic cycle stability compared to the W-x films because the bonding strength between the ITO glass electrode and the WO3 film was enhanced by polydopamine (PDA) film. Notably, the PW-2 film still retained 90.8% of its original optical contrast after 5000 cycles. In addition, both the W-2 and PW-2 films exhibited high optical contrast from visible to infrared regions owing to their 3D network nanoporous structure; their optical contrasts were 71.5% and 69.7% at 700 nm, respectively. Both the W-2 and PW-2 films also exhibited high coloration efficiency and areal capacitance; their coloration efficiencies were 80.4 and 72.5 cm2/C, and areal capacitances were 59.38 and 75.32 mF/cm2, respectively. PW-2 film is promising for electrochromic energy-saving smart windows with power storage.
Co-electrolysis of H2O and CO2 by high-temperature solid oxide electrolysis cells (SOECs) is a useful approach for energy storage and carbon dioxide reduction. In this study, we conducted H2O/CO2 ...co-electrolysis using a flat-tube SOEC and studied its electrochemical performance and durability. It was found that the increase of temperature and water fraction in fuel gas promote electrochemical performance. In addition, the co-electrolysis was found to be stable with a constant current density of 300 mA cm−2 for over 1000 h at 750 °C. The contribution of each electrode process to polarization resistance is elucidated by electrochemical impedance spectroscopy and distribution of relaxation time (DRT) analysis. The fuel electrode was found to degrade more significantly against duration time as compared to the oxygen electrode. Post-mortem analysis of the microstructure revealed the loss and sintering of Ni particles in active cathode functional layer at the inlet of the fuel electrode. Based on these results, the degradation mechanism of H2O/CO2 co-electrolysis by the flat-tube SOEC was discussed in details.
•H2O/CO2 co-electrolysis was successfully conducted by using a flat-tube (FT) SOEC.•Performance of the FT cell for co-electrolysis was studied by EIS and DRT methods.•1000 h of co-electrolysis has been carried under a current density of 300 mA cm−2.•The loss and agglomeration of Ni are the important causes of cathode degradation.
COVID-19 was declared a pandemic by WHO on March 11, 2020, the first non-influenza pandemic, affecting more than 200 countries and areas, with more than 5·9 million cases by May 31, 2020. Countries ...have developed strategies to deal with the COVID-19 pandemic that fit their epidemiological situations, capacities, and values. We describe China's strategies for prevention and control of COVID-19 (containment and suppression) and their application, from the perspective of the COVID-19 experience to date in China. Although China has contained severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and nearly stopped indigenous transmission, a strong suppression effort must continue to prevent re-establishment of community transmission from importation-related cases. We believe that case finding and management, with identification and quarantine of close contacts, are vitally important containment measures and are essential in China's pathway forward. We describe the next steps planned in China that follow the containment effort. We believe that sharing countries' experiences will help the global community manage the COVID-19 pandemic by identifying what works in the struggle against SARS-CoV-2.
•A CMC/CPAM/SBR ternary composite binder is proposed for Si-based anode.•Multifunctional groups are designed for matching the surfaces of both Si and carbon.•Regional elasticity and integral ...rigidness are achieved for the volumetric effects.•The cyclability of a Si@C/graphite blended anode is improved.•The binder is effective in high-loading electrodes and full cells.
Si/C blend anodes hold great promise in commercialized high-energy-density (HED) Li-ion batteries but suffer from volumetric effects and electrode integrity deterioration. This study reports a ternary composite binder consisting of carboxymethyl cellulose (CMC), cationic polyacrylamide (CPAM), and styrene-butadiene rubber (SBR), which can significantly improve the cyclability of a Si@C/graphite blend anode. A high capacity retention of 92.9% after 100 cycles was achieved in a half cell. Moreover, the ternary binder proves suitable for a very high mass loading (4.9 mAh/g) electrode and is effective in a 2 Ah-level full cell, which delivers an excellent capacity retention of 80.6% after 500 cycles. The beneficial effects were ascribed to the multifunctional groups compatible with the surfaces of both Si and carbon, and the designed rigidness and elasticity which restricts and accommodates the volumetric effects of the Si/C blend anode simultaneously.
PDF
