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The UPS results indicated that although the electron affinity of ZnO could be effectively tuned by doping Ga, it remained quite stable for GZO under oxygen rich condition.

To fully exploit the superiority of tubular structures, in this study, we systematically explore the optimal preparation conditions for Ni/Co3O4, including cation species and content, additive species and content, and anion species. Our results reveal that the formation of an initial cobalt nickel acetate hydroxide prism is the key factor and directly affects the final microtubular structure. Moreover, P is subsequently doped into the Ni/Co3O4 lattice to increase the M3+/M2+ molar ratio (M = Co and Ni), promote reaction kinetics, and optimize electronic structure. Consequently, the oxygen evolution reaction performance of P-doped tubular Ni/Co3O4 is significantly higher than that of undoped Ni/Co3O4 and the state-of-the-art RuO2 electrocatalyst.

The electrochemical oxygen evolution reaction (OER) plays an important role in many clean electrochemical energy storage and conversion systems, such as electrochemical water splitting, rechargeable metal–air batteries, and electrochemical CO2 reduction. However, the OER involves a complex four-electron process and suffers from intrinsically sluggish kinetics, which greatly impairs the efficiency of electrochemical systems. In addition, state-of-the-art RuO2-based OER electrocatalysts are too expensive and scarce for practical applications. The development of highly active, cost-effective, and durable electrocatalysts that can improve OER performance (activity and durability) is of significant importance in realizing the widespread application of these advanced technologies. To date, considerable progress has been made in the development of alternative, noble metal-free OER electrocatalysts. Among these alternative catalysts, transition metal compounds have received particular attention and have shown activities comparable to or even higher than those of their precious metal counterparts. In contrast to many other electrocatalysts, such as carbon-based materials, transition metal compounds often exhibit a surface reconstruction phenomenon that is accompanied by the transformation of valence states during electrochemical OER processes. This surface reconstruction results in changes to the true active sites and an improvement or reduction in OER catalytic performance. Therefore, understanding the self-reconstruction process and precisely identifying the true active sites on electrocatalyst surfaces will help us to finely tune the properties and activities of OER catalysts. This review provides a comprehensive summary of recent progress made in understanding the surface reconstruction phenomena of various transition metal-based OER electrocatalysts, focusing on uncovering the correlations among structure, surface reconstruction and intrinsic activity. Recent advances in OER electrocatalysts that exhibit a surface self-reconstruction capability are also discussed. We identify possible challenges and perspectives for the development of OER electrocatalysts based on surface reconstruction. We hope this review will provide readers with some guidance on the rational design of catalysts for various electrochemical reactions.

Extractive distillation is widely accepted and commercialized for separating azeotrope mixtures, but using traditional organic solvents leads to intrinsic obstacles such as the high energy requirement and solvent-related environmental problems. Benefiting from the development of green solvents, using ionic liquids instead of traditional solvents as entrainers for extractive distillation has attracted wide attention. This paper presents a multi-objective optimization strategy to integrate the design and control of the ionic liquid-based extractive distillation processes. In the optimization processes, the condition number (CN) and total annual cost (TAC) are minimized as the objective functions to evaluate the control properties and design of three different separation systems. The optimization results are shown by the Pareto front, which is based on trade-offs between controllability and economics. The environmental impact is evaluated by the environmental impact potential of energy for each system in a posterior stage during the optimization processes. Designs with minimum TAC (PT), trade-off designs between TAC and CN (PO) and designs with minimum CN (PC) on Pareto front are optimized and compared. The results show that the increase of reflux ratio can improve the control properties for the ionic liquid-based extractive distillation processes. Furthermore, the dynamic simulation of PT and PO are carried out to compare their dynamic responses based on the same dynamic control structure, and PO shows better performance in the aspects which include maximum deviation and residual error of dynamic response.

A copper magnetite nanohybrid catalyst (Cu-Fe3O4/Cu/C), abundant of Schottky interfaces and structural defects, with ultrathin encapsulation of graphitic carbon, was synthesized and tested. The cat...

Transition metal oxides (TMOs) have acquired much attention on account of their abundant reserves and variable components, but sluggish charge transfer rate, limited electrochemically active sites,...

The application of ionic liquids in separating complex ternary azeotropic system via extractive distillation (ED) is investigated. Five configurations using 1-butyl-3-methylimidazolium dicyanamide ...

A method for efficiently catalyzing the oxygen evolution reaction (OER) represents a top priority for water electrolysis due to its multistep electron transfer pathway and sluggish kinetics. The OE...

Large-scale commercialization of water splitting is still challenging due to the lack of efficient, cost-effective and robust electrodes. In this work, Co9S8–Ni3S2 heterointerfaced nanotubes on Ni foam (Co9S8–Ni3S2 HNTs/Ni) have been successfully developed via a two-step hydrothermal method as a highly efficient, robust and flexible bifunctional electrodes for water splitting. Co9S8–Ni3S2 HNTs are composed of inner 1D Co9S8 nanotubes surrounded by outer 2D Ni3S2 nanosheets. Co9S8–Ni3S2 HNTs/Ni electrode achieves 10 mA cm−2 at overpotentials of 85 mV for H2 evolution reaction (HER) and 50 mA cm−2 at overpotential of 281 mV for O2 evolution reaction (OER) in 1 M KOH solution, substantially better than that on single-phased Co9S8 nanotubes and Ni3S2 nanosheets on Ni foam. The reason is most likely due to formation of defect-rich heterointerfaces between Co9S8 nanotubes and Ni3S2 nanosheets, and the significant change of binding energies of Co 2p and Ni 2p level between the Co9S8 and Ni3S2, leading to the synergistic effect on the enhanced catalytic activity for HER and OER. The robust and flexibility of Co9S8–Ni3S2 HNTs/Ni electrodes are demonstrated in an alkaline electrolyzer, delivering 10 mA cm−2 electrolysis current at a cell voltage of 1.59 V, one of the best bifunctional electrodes for water splitting. Owing to the fact that reaction occurs at the defects-rich heterointerfaces, the Co9S8-Ni3S2 HNTs/Ni electrodes are structurally very stable.

The development of cost-effective electrocatalysts with high activity and sufficient stability for hydrogen evolution reaction (HER) is crucial for the widespread application of water electrolysis for sustainable H

A simple method is provided to achieve in situ surface reconstruction synthesis of a heterostructural NiO/Ni film on carbon cloth (NiO/Ni@CC) for the hydrogen evolution reaction (HER). This ultrafast reconstruction process brings a hydrophilic surface and abundant heterostructures with rich oxygen vacancies exhibiting a low HER overpotential and remarkable stability.

Highly active and earth-abundant catalysts for hydrogen evolution reaction (HER) play a crucial in the development of efficient water splitting to produce hydrogen fuel. Here, we reported a simple, facile and effective strategy to fabricate N-doped molybdenum sulfide (N-doped MoS2) as noble metal-free catalysts for HER. Compared with pure MoS2, the obtained N-doped MoS2 catalyst revealed enhanced HER performance with low overpotential of −168 mV (−10 mA cm−2), small Tafel slope of 40.5 mV dec−1 and excellent stability. The superior HER activity may originate from both the exposed Mo active sites due to S defects and the optimized electron density state of S atoms by N doping. More importantly, due to its simple synthesis method, earth-abundant catalysts and high catalytic activity, the N-doped MoS2 will become a promising HER catalysts for water splitting.

Heteroatom-doped carbon materials as efficient electrocatalysts for oxygen reduction reaction have been attracted a lot of research interest. For its low cost, high selectivity and excellent stability, heteroatoms-doped carbon materials have been considered as the candidate for replacing Pt-based catalysts. We had designed an iron and phosphorus co-doped carbon nanofibers (Fe-P/CNFs) derived from bacterial cellulose for oxygen reduction reaction, which not only showed a three-dimensional (3D) porous network structure, but also possessed large surface area. The unique 3D porous network could accelerate oxygen diffusion and electron transfer, and meanwhile enlarge specific surface area. Accordingly, the obtained material had more active sites for electrocatalysis. More importantly, the unusual synergistic effects between the doped Fe and P atoms could efficiently improve the electrocatalytic performance of oxygen reduction reaction. As expected, the Fe-P/CNFs showed a high ORR electrocatalytic activity with a more positive onset potential of 1.01 V, similar with 1.03 V at 20 wt% Pt/C, and a good long-term stability (94% retention of current density after chronoamperometry 20,000s).

Developing highly efficient electrocatalysts with earth abundant elements for oxygen evolution reaction (OER) is a promising way to store light or electrical energy in the form of chemical energy. Here, a new type of electrocatalyst with core-shell carbon/NiCo

The oxygen evolution reaction (OER), as a key half-reaction in water splitting for clean hydrogen energy, is kinetically sluggish and usually requires efficient electrocatalysts to reduce the overpotential. Herein, we report a simple method to synthesize novel two-dimensional Ni76Co24 layered double hydroxides (Ni76Co24–LDHs) nanosheets as an effective OER catalyst. The obtained Ni76Co24–LDHs display a low onset overpotential of 242 mV, along with an excellent cycling stability. The Tafel slope of Ni76Co24–LDHs is only 57 mV dec−1 which demonstrates an active kinetics for OER. The high catalytic activity of Ni76Co24–LDHs may be attributed to the porous tremella-like structure with large surface area, synergistic effect of Ni and Co, and a pinning of the Co3+/4+ and Ni3+/4+. More importantly, the high catalytic property and simple synthetic method of Ni76Co24–LDHs may have a promising potential for practical application.

Metal-Nx-C based materials have emerged as one of the most promising electrocatalysts for electrochemical reduction of carbon dioxide (ERCD). Co-based macrocyclic compounds have shown unique performance, however, of which the relationship between the ligands structure surrounding Co–N4 centers and reaction mechanism remains vague. To explore this issue, here, a series of Co-based macrocyclic compounds are elaborately chosen as model catalysts, including phthalocyanine cobalt (CoPc), cobalt (II) meso-Tetraphenylporphine (CoTp) and cobalt tetramethoxyphenylporphyrin (CoTop), which possess well-defined Co-N4 coordinated centers but different ligands structure surrounding Co-N4. Electrochemical measurements show that CoPc possesses higher activity and selectivity for CO with Faradaic efficiency (FE) above 62% at −0.7 V (vs. RHE) relative to those of CoTp and CoTop. Combining density functional theory (DFT) calculations, it can be further confirmed that CoPc is more favorable for ERCD to CO due to the rapid formation of key intermediate COOH* and the desorption of CO, demonstrating that the structure of ligands (phthalocyanine) surrounding Co-N4 plays a crucial role in the high CO selectivity. It can be anticipated that an exclusive strategy will pave a new avenue for further understanding the ERCD mechanism of Co-Nx-C catalysts.

We report a low cost, environmentally friendly nitrogen (N) and phosphorus (P) co-doped porous carbon nanowires derived from bacterial cellulose which acts as the efficient electrode materials for the supercapacitor. The as-prepared material exhibits a large specific capacitance of 258 F/g at a current density of 1 A/g and an excellent cycling stability of 30000 cycles. The excellent electrochemical performance is attributed to the synergistic effect of P and N doping in carbon nanowires and the unique three-dimensional network and porous structure. In addition, a symmetric supercapacitor has been fabricated by exploiting the as-prepared material as a positive electrode and negative electrode. The as-fabricated symmetric supercapacitor shows promising energy density of 5.4 Wh/kg at high power density of 200 W/kg, along with an excellent cycle stability of 87 % specific capacitance retention after 6000 cycles. The advanced specific capacitance and excellent cycle stability of the carbon nanowires imply that it could be a potential candidate in commercial applications of supercapacitors.

Activated carbons (ACs) were prepared from peanut shells by KOH activation under microwave heating and were used as electrode materials for electrochemical capacitors (ECs). The pore structure of the ACs was characterized by nitrogen adsorption and the electrochemical performance by galvanostatic charge–discharge and cyclic voltammetry. Results show that the ACs’ specific surface area, total pore volume, specific capacitance, as well as energy density are maximized using an activation time from 6 to 10 min or KOH/peanut shell mass ratio from 0.6 to 2.0 under otherwise identical conditions. When the KOH/peanut shell mass ratio was 1.0, microwave power was 600 W and activation time was 8 min, the specific surface area of the resulting AC was 1277 m 2 /g and its energy density was 8.38 W h/kg after 1000 cycles. The KOH activation of peanut shells with microwave heating is an efficient approach for the rapid preparation of low cost ACs for ECs. [New Carbon Materials 2015, 30(1): 86–91]

Recently, nitrogen-doped carbon materials have attracted immense interest because of their great potential in various applications. In this work, FeN-doped carbon microspheres are large-scale synthesized using basic magnesium carbonate as the template and glycine as the carbon and nitrogen precursor by a simple liquid impregnation method under a relatively low pyrolysis temperature. Iron is introduced into the carbon microspheres to enhance the graphitic degree and improve the electrocatalytic performance. This carbon material with high specific area, high nitrogen content and part-graphitization shows high activity and four-electron selectivity for the oxygen reduction reaction in an alkaline medium. Compared to a commercial Pt/C catalyst, this material presents exceeding stability and durability, which can be a candidate for potential applications in the fuel cell and electrochemical industries of oxygen reduction.

The Ni 3 S 2 nanoparticles have been successfully grown on the carbon nanofibers (CNFs) derived from bacterial cellulose via a hydrothermal method, which the as-prepared composite exhibited high specific capacitance (883 F g −1 at 2 A g −1 ), much more than CNFs (108 F g −1 at 2 A g −1 ), and good cycle stability. The asymmetric supercapacitor was designed to contain the CNFs coated Ni 3 S 2 nanoparticles (Ni 3 S 2 /CNFs) as positive electrode and CNFs as negative electrode in 2 M KOH electrolyte. Due to the synergistic effects of the two electrodes, asymmetric cell showed superior electrochemical performances. The optimized asymmetric supercapacitor gave a operating potential of 1.7 V in 2 M KOH aqueous solution, exhibiting a high specific capacitance of 56.6 F g −1 at 1 A g −1 and considerably high energy density of 25.8 Wh kg −1 at a power density of 425 W kg −1 . Meanwhile, Ni 3 S 2 /CNFs//CNFs asymmetric supercapacitor showed excellent cycling stability with 97% specific capacitance retained after 2500 cycles.

Flake-like Co/Al layered double hydroxides (Co/Al LDHs) were synthesized by using a facile and free-template hydrothermal method. Reduced graphene oxide (rGO) is obtained by a simple, clean and controlled hydrothermal reduction route to convert graphene oxide (GO) to stable graphene solution which avoided reductant. Because of their unique structure, both materials exhibit excellent electrochemical performances, which the maximum specific capacitance of Co/Al LDHs is 1158F/g and rGO is 223.2F/g. An asymmetric capacitor incorporating the LDHs as the positive electrode and the rGO as the negative electrode was fabricated. The experimental results indicate that the optimized asymmetric supercapacitor shows intriguing performances with a maximum specific capacitance of 97.5 F/g and high energy density of 34.7Wh/kg at a cell voltage of 1.6 V. A good electrochemical stability with 93% specific capacitance retained was demonstrated after consecutive 2000 cycle numbers. Because of the large mass loading and high energy density, this device after 2000 cycles still drives a red light-emitting-diode (LED). This impressive result presented here may have outstanding potential in commercial applications.

Ruthenium/mesoporous carbon (Ru/MC) composites for supercapacitors were synthesized from RuCl 3 and peanut shell-derived MC by a microwave-assisted heating glycol reduction method. The specific capacitance of obtained Ru/MC composite increased with the increasing Ru mass loaded, maintaining 287 F g −1 even after 1000 cycles at 20% loading of Ru for Ru 20 /MC. The contribution of Ru nanoparticles reached 48.7% of the total capacitance. The energy density of Ru 20 /MC capacitor in 6 M KOH electrolyte only dropped from 10.5 Wh kg −1 to 9.8 Wh kg −1 with the energy density retention of 93.3% after 1000 cycles, showing excellent cycle stability. The results indicate that the one-step microwave-assisted glycol reduction of RuCl 3 is a simple technique to the preparation of high performance Ru/MC composites for supercapacitors.

Developing highly efficient electrocatalysts with earth abundant elements for oxygen evolution reaction (OER) is a promising way to store light or electrical energy in the form of chemical energy. Here, a new type of electrocatalyst with core-shell carbon/NiCo2 O4 double microtubes architecture is successfully synthesized through a hydrothermal method combined with the calcination process with wet tissues as the template and carbon resource. The outer NiCo2 O4 nanosheet arrays contain abundant defects, which come from reduction of the carbon in wet tissues. This indicates that carbon is a very excellent defect inducer. The inner carbon microtubes can act as the robust structure skeleton and these core-shell double microtubes provide abundant diffusion channels for oxygen and electrolyte, both of which contribute to improving the stability by avoiding damage to the electrode from produced O2 bubbles and the collapse of the outer NiCo2 O4 microtubes. Electrochemical results show that the electrode, core-shell carbon/NiCo2 O4 double microtubes loaded on carbon cloth, exhibits prominent electrocatalytic activity with an overpotential of only 168 mV at 10 mA cm-2 and a Tafel slope as low as 57.6 mV dec-1 in 1.0 mol L-1 KOH. This new type of electrocatalyst possesses great potential in water electrolyzers and rechargeable metal-air batteries.

The development of metal-free catalysts to replace the use of Pt has played an important role in relation to its application to fuel cells. We report N-doped carbon nanofibers as the catalyst of an oxygen reduction reaction, which were synthesized via carbonizing bacterial cellulose-polypyrrole composites. The as-prepared material exhibited remarkable catalytic activity toward the oxygen reduction reaction with comparable onset potential and the ability to limit the current density of commercial Pt/C catalysts in both alkaline and acid media due to the unique porous three-dimensional network structure and the doped nitrogen atoms. The effect of N functionalities on catalytic behavior was systematically investigated. The results demonstrated that pyridinic-N was the dominating factor for catalytic performance toward the oxygen reduction reaction. Additionally, N-doped carbon nanofibers also demonstrated excellent cycling stability (93.2% and 89.4% retention of current density after chronoamperometry 20 000 s in alkaline and media, respectively), obviously superior to Pt/C.

We report a new environmentally-friendly synthetic strategy for large-scale preparation of 16 nm-ultrathin NiCo based layered double hydroxides (LDH). The Ni50Co50-LDH electrode exhibited excellent specific capacitance of 1537 F g−1 at 0.5 A g−1 and 1181 F g−1 even at current density as high as 10 A g−1, which 50% cobalt doped enhances the electrical conductivity and porous and ultrathin structure is helpful with electrolyte diffusion to improve the material utilization. An asymmetric ultracapacitor was assembled with the N-doped graphitic ordered mesoporous carbon as negative electrode and the NiCo LDH as positive electrode. The device achieves a high energy density of 33.7 Wh kg−1 (at power density of 551 W kg−1) with a 1.5 V operating voltage.

Mesoporous carbons (MCs) with high surface area of 1409–1552 m2 g−1 for supercapacitors were prepared from peanut shell by one-step microwave-assisted ZnCl2 activation. The MC made at the ZnCl2/peanut shell mass ratio of 4 in 20 min at 600 W microwave power (nominated as MC4-M) retains a high specific capacitance of 184 F g−1 at 0.05 A g−1 current density after 1000 cycles, showing perfect cycle stability. At 1.6 A g−1 current density, the energy density of the supercapacitor made from MC4-M reaches 4.94 Wh kg−1 at 740 W kg−1, exhibiting excellent rate performance. The findings clearly indicate that the one-step microwave-assisted ZnCl2 activation technique is a facile approach to the preparation of high performance MCs for supercapacitors.

We present a novel method based on image fusion and fuzzy clustering for change detection in remote sensing images. Firstly, the difference images by differencing operator and log-ratio operator are decomposed using Undecimated Discrete Wavelet transform (UDWT). Then, wavelet coefficients are fused to obtain multiscale feature vectors. By taking into account the spatial-neighborhood information, a change detection algorithm based fuzzy local-information C-means (FLICM) clustering is developed to obtain final detection results. Experiment confirms that the proposed approach does better than the differencing and log-ratio operators.

Two alloys of Fe-26.4wt%Mn-6.2wt%Si-5.2wt%Cr (Alloy 1) and Fe-30wt%Mn-6.0wt%Si-5.3wt%Cr (Alloy 2) were prepared by vacuum induction melting. The starting temperature of fcc to hcp phase transformation, Ms, and the mean austenite grain size, D, increase with increasing the austenitizing temperature for both Fe-Mn-Si-Cr alloys. The Ms temperature maintains an exponential relationship with the reciprocal of the grain size as Ms = A exp ({minus}B/D), which may be related to the probability of finding the nucleation sites formed by the overlapping of stacking faults for coarser grains.

International organization's policy system for social assessment is a relatively sophisticated policy framework, under which social assessment follows the sociological paradigm in terms of policy, concept and operating standard, social factors are well incorporated into projects for investigation, attention is paid to the interests of vulnerable groups such as the poor, women, displaced persons and ethnic minorities, the positive and negative impacts of a project are studied, and necessary social actions are taken to forecast an d evade potential social risks. The need for social assessment has developed gradually with foreign investment in China, social assessment was started lately and there are still some gaps from the requirements of the international financial organizations, Accordingly, it is very necessary to draw experience from international financed projects and build a policy system and operation manual for social assessment conducive to China's development.

The setup of a supervision and management system for the whole process of resettlement of a water resources or hydropower project can provide a standard and basis for regulating the supervision and management behavior by the government departments or agencies, employer, contractor, supervisory agency, displaced persons and other stakeholders, and an important guide for effective resettlement planning, implementation and subsequent support. This paper builds a whole-process resettlement supervision and management system in accordance with the Regulations on Land Acquisition Compensation and Resettlement for Construction of Large and Medium-sized Water Resources and Hydropower Projects promulgated by the State Council in 2006 on the basis of a review of domestic and foreign regulations and policies on supervision and management of reservoir resettlement, and an investigation of the practice of resettlement monitoring and evaluation of water resources and hydropower projects. It is thought that this system should include the whole-process supervision of the government and the whole-process monitoring and evaluation of social organizations, the roles and tasks of different subjects and objects of supervision, the scope and methodology of supervision, and the qualification management of supervisory agencies at different stages have been defined.