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Electrochemistry and X-ray absorption spectroscopy (XAS) of MnO2/reduced graphene oxide (RGO) were made to evaluate capacitive performance and electronic structure as a supercapacitor. MnO2 was deposited on the surface of RGO by a spontaneous redox reaction. At low current density (1 A g−1), the specific capacitance of MnO2/RGO (MRGO) greatly increased with increasing growth time from 281 to 462 F g−1. Electrochemical results show that the specific capacitance of RGO and MRGO arises from the combined contributions of electrochemical double-layer capacitance (EDLC) and pseudo-capacitance. To gain insights into the charge storage mechanism of RGO and MRGO, it was characterized using ex-situ soft XAS techniques at Mn L-edge and C, O K-edges in the charging/discharging process. The ex-situ soft XAS results provide evidence that the contribution of RGO to specific capacitance involves an oxygen-functionality-related contribution of pseudocapacitance and EDLC. In addition, the specific capacitance of MRGO reveals pseudocapacitive contributions from the redox processes that involve the Mn(III)/Mn(IV) redox reaction in MnO2. This work utilizes electrochemical and ex-situ XAS techniques to elucidate charge storage mechanism for supercapacitor applications.

Carbon nitride-based photocatalysts hold an enormous potential in producing hydrogen. A strategy to simultaneously create isotype heterojunctions and active sites in highly-crystallized carbon nitride is anticipated to significantly boost the photocatalytic activity, but is yet to be realized. Herein, we find that cobalt salt added in the ionothermal synthesis can promote the phase transition of heptazine-based crystalline carbon nitride (CCN) to triazine-based poly(triazine imide) (PTI), rendering the creation of single-atom cobalt coordinated isotype CCN/PTI heterojunction. Co-CCN/PTI exhibits an appreciable apparent quantum yield of 20.88% at 425 nm for photocatalytic hydrogen production with a rate achieving 3538 μmol h−1 g−1 (λ > 420 nm), which is 4.8 times that of CCN and 27.6 times that of PTI. The high photocatalytic activity is attributed to the Type II isotype highly-crystallized CCN/PTI heterojunction for promoting charge carrier migration, and the single-atom Co sites for accelerating surface oxidation reaction.

A kind of graphitic carbon nitride (TSC−550) with high polymerization degree and improved surface property was prepared by a new precursor of thiosemicarbazide. The sulfur motif and high nitrogen content in thiosemicarbazide promoted the polymerization of thiosemicarbazide to form graphitic carbon nitride framework with high degree of polymerization, which significantly influenced the electronic structure and surface chemical properties. TSC−550 possessed a narrow bandgap of 2.19 eV that facilitated the utilization of visible light, and possessed a less positive charge, acidic surface that resulted in enhanced hydrogen adsorption ability in water solution, which promoted the H2 evolution kinetics. In addition, the extended π-conjugated electronic system promoted the separation and migration of photo-generated charge carries in plane of TSC−550 framework, as well as the increasing interlayer C–N interactions in TSC−550 created conductive paths across the layers to tunnel interlayers for rapid electron transportation. As a result, TSC−550 nanosheets showed excellent photocatalytic H2 production activity, the AQY achieved 36.4% at 425 nm.

Electro-oxidation of 5-hydroxymethylfurfural (HMFOR) is a promising green approach to realize the conversion of biomass into value-added chemicals. However, considering the complexity of the molecular structure of HMF, an in-depth understanding of the electrocatalytic behavior of HMFOR has rarely been investigated. Herein, the electrocatalytic mechanism of HMFOR on nickel nitride (Ni3N) is elucidated by operando X-ray absorption spectroscopy (XAS), in situ Raman, quasi in situ X-ray photoelectron spectroscopy (XPS), and operando electrochemical impedance spectroscopy (EIS), respectively. The activity origin is proved to be Ni2+δN(OH)ads generated by the adsorbed hydroxyl group. Moreover, HMFOR on Ni3N relates to a two-step reaction: Initially, the applied potential drives Ni atoms to lose electrons and adsorb OH− after 1.35 VRHE, giving rise to Ni2+δN(OH)ads with the electrophilic oxygen; then Ni2+δN(OH)ads seizes protons and electrons from HMF and leaves as H2O spontaneously. Furthermore, the high electrolyte alkalinity favors the HMFOR process due to the increased active species (Ni2+δN(OH)ads) and the enhanced adsorption of HMF on the Ni3N surface. This work could provide an in-depth understanding of the electrocatalytic mechanism of HMFOR on Ni3N and demonstrate the alkalinity effect of the electrolyte on the electrocatalytic performance of HMFOR.

This study investigates optimal large-scale offshore wind turbines (OWT). The blade data for large-scale OWTs is developed using the NREL 5-MW baseline OWT and validated using the DTU 10-MW reference one, where the blade parameters for OWTs ranging from 5 to 17 MW are established. Interpolation, extrapolation, and regression analyses are used to obtain the relationship between the chord length and three blade properties, as well as the relationship between the nacelle mass and rotor diameter. The chord length and rotor radius are then adjusted based on the NREL 5-MW OWT to obtain the required rated power contour figure using FAST. One can use the rated power and critical blade out-of-plane deflection to determine the chord length and rotor radius factors, and the required FAST input files can thus be generated. In this study, 5- to 16-MW OWTs are selected to conduct a support structure analysis and to determine the optimal steel design. Based on the relationship between the rated power with the blade weight and the steel weight of the support structure, OWTs with a rated power ranging from 9 to 15 MW is suitable. The 12-MW one should be optimal, and those over 15 MW are not economic.

Surface treatment is an effective method to improve the photoelectrochemical (PEC) performance of photoelectrodes. Herein, we introduced a novel strategy of surface sulfurization to modify hematite (α-Fe2O3) nanorods grown in an aqueous solution, which triggered encouraging improvement in PEC performances. In comparison to the solution-grown pristine α-Fe2O3 nanorod photoanode that is PEC inefficient and always needs high temperature (>600 °C) activation, the surface sulfurized α-Fe2O3 nanorods show photocurrent density increased by orders of magnitude, reaching 0.46 mA cm−2 at 1.23 V vs. RHE (reversible hydrogen electrode) under simulated solar illumination. This improvement in PEC performances should be attributed to the synergy of the increased carrier density, the reduced surface charge carrier recombination and the accelerated water oxidation kinetics at the α-Fe2O3/electrolyte interface, as induced by the incorporation of S ions and the formation of multi-state S species (Fe-Sx-Oy) at the surface of α-Fe2O3 nanorods. This study paves a new and facile approach to activate α-Fe2O3 and even other metal oxides as photoelectrodes for improved PEC water splitting performances, by engineering the surface structure to relieve the bottlenecks of charge transfer dynamics and redox reaction kinetics at the electrode/electrolyte interface.

In this work we propose a study to determine the structure of Fe and Co doped TiO2 by using the Fe K-edge, Co K-edge and Ti K- edge X-ray absorption near edge spectroscopy. The detailed analysis of Fe and Co-doped TiO2 before and after Methylene blue (MB) treatment was examined under the irradiation of 35 W xenon arc lamp for 3 h. The materials treated with MB were studied by X-ray absorption spectroscopy, EPR and FT-IR which revealed that the oxidation state of Co2+ was photo-oxidized to Co3+ and Fe3+ was photo-reduced to Fe2+ or less. Thermodynamic, kinetic properties were studied at different reaction temperature and the activation energy (Ea), enthalpy (ΔH), entropy (ΔS) and free energy (ΔG) of activation were calculated for the reaction. The activation energy has been found for TiO2, Fe TiO2 and Co TiO2 as 24.771, 11.413 and 15.801 kJ mol−1 respectively. The structure, morphology and optical properties were studied by XRD, UV-diffuse reflectance spectra, FESEM, TEM and PL. Moreover, electrochemical studies were carried out to demonstrate the oxygen evolution reaction (OER) activity on TiO2, Fe TiO2 and Co TiO2 in 1 M of H2SO4 electrolyte, with a scan rate of 50 mV s−1 and the as-prepared photocatalysts could act as the promising electrode materials for water splitting.

Electrochemical and ex-situ X-ray absorption spectroscopic (XAS) measurements of NiCo2O4 that have been annealed in different gases (Ar and air) were made to evaluate the efficiency of its electrocatalysis of hydrogen generation by the electrolysis of urea. The electrochemical and XAS measurements demonstrated that NCO–Ar contain significant amounts of Co2+ in octahedral coordination was more favorable than NCO-air for urea electrolysis owing to the effective exposure of electrochemical active sites to participate in the Faradic redox reaction. Further insight into the electrocatalytic mechanism of NiCo2O4-based materials during urea electrolysis was obtained using ex-situ soft XAS. The results of ex-situ soft XAS revealed that the variation of the octahedral and tetrahedral coordinations of Co2+ in NCO–Ar and NCO-air importantly contributes to electrocatalytic behavior. NCO–Ar exhibits excellent electrocatalytic activity towards the Co redox couples in a repetitive cycling process owing to the creation of highly efficient active sites (octahedral Co2+). This study presents importantly x-ray spectroscopic determination of the change in electronic structure of catalyst for hydrogen production.

Recently, a novel rechargeable Al ion battery (AIB) with high performance has been developed. Owing to its low cost, high-rate capability, excellent cyclability, and non-flammability, AIB provides a safe alternative to many commercial batteries used in the energy storage system. To improve its performance, identifying molecular structure and arrangement of chloroaluminate anion (AlCl4−) intercalated in the graphite layer remains a great challenge. In this work, operando analysis of X-ray diffraction (XRD) measurement and X-ray absorption (XAS) spectroscopy were performed to investigate the intercalation of AlCl4− anion and related molecular arrangement in the graphite layers. The intercalated stage and intercalant gallery height of graphite cathode electrode during AIB battery operation were observed to be stage 3 and 9.22 A, respectively. Furthermore, the spectral evolution from ex-situ XAS at the Al and Cl K-edge was associated with closely packed intercalation of AlCl4− molecules. With density functional theory (DFT) calculation, three simulated models of intercalated AlCl4− molecules in the graphite layer were revealed successfully, which explained possible molecular structures at different charging states. This analytical methodology paves the way for better understanding the structural transformation of molecular ions de-/intercalation in graphite layers.

Highly efficient non-noble materials for water splitting are essential for renewable energy application. Herein, cobalt phosphide nanoparticles with high P/Co ratio are synthesized and display overpotentials of 348 mV (or 343 mV) for oxygen evolution reaction (OER) with surface oxidized active species formed and 200 mV (or 184 mV) for hydrogen evolution reaction (HER) in 1 M NaOH (or 1 M KOH) at 10 mA cm−2. The improved OER could be ascribed to the smaller particle size for increased active site number and more importantly the improved intrinsic activity probably assisted by more phosphates formed during electrocatalytic reaction; while the improved HER performance is mainly attributed to the increased active sites in the form of Co P bonds. In a two-electrode configuration, the catalysts exhibit excellent overall water splitting performance, with 10 mA cm−2 at 1.58 V and a long-time reaction stability without attenuation during 10 h operation.

The interface between Pt nanoparticles and support materials is of critical importance for tuning the electrocatalytic properties. The physical and chemical characteristics of metal oxide would influence the electronic and physical interactions with Pt nanoparticles. Engineering the interface interaction between Pt and CeO2 may be an effective way to modulate the electrocatalytic activity for electro-oxidation of methanol (MOR). Herein, ceria nanorods with rich oxygen vacancies (Vo) and rough surface have been induced by plasma surface engineering, and used as Pt support. For the special property of ceria, the particle size and dispersion of Pt nanoparticles could be well modified, the interaction of Pt and ceria are also regulated. Interestingly, the abundant Vo on ceria surface afford surplus electrons, which would transfer to the sub-surface with decreased Ce valence in the sub-surface of CeO2, and change the electron transfer between Pt and ceria, increase the electron density of Pt. Due to unique electron structure of Pt and CeO2, MOR catalytic activity and durability of the electrocatalyst are significantly enhanced.

Inspired by photosynthesis in nature, artificial photosynthesis (AP) systems have been widely investigated in the context of energy and environmental research. Here we report a noble-metal-free AP system for visible-light-driven H2 generation from aqueous solutions consisting of fluorescein (FL) as photosensitizer, single-layer ultrasmall MoS2 nanoplates embedded in carbon nanofibers (CNF) as electron relay and redox catalyst, and triethanolamine (TEOA) as sacrificial electron donor. This CNF–MoS 2/FL system exhibits outstanding H2 evolution performance, with an H2 generation rate that exceeds not only both MoS2/FL (by 100%) and CNF/FL (by 1100%), but also the Pt/FL system (by 40%). The excellent photocatalytic activity of this CNF–MoS2/FL system can be ascribed to the synergistic effects of CNF and MoS2 coupling: (1) the simultaneous presence of MoS2 with its delocalized and increased Mo 4d unoccupied states and of CNF with increased graphitic characteristics enables electron transfer from FL∗ to MoS2 via CNF electron relay; (2) the single-layered ultrasmall MoS2 nanoplates with short effective lengths for electron transfer and high density of reactive S-edges effectively catalyze the H2 evolution reaction (HER). The presented work successfully fabricated a highly efficient AP system for solar H2 production from a fully aqueous solution and indicated CNF–MoS2 as a promising candidate to replace Pt for solar fuel conversion.

To determine whether liver lobe-based DCE-MRI can be used to detect the presence and Child-Pugh class of hepatitis B-related cirrhosis.Fifty-six cirrhotic patients with hepatitis B and 20 healthy participants underwent liver DCE-MRI, and the positive enhancement integral (PEI), time to peak (TTP), maximum slope of increase (MSI) and maximum slope of decrease (MSD) of the left lateral liver lobe (LLL), left medial liver lobe (LML), right liver lobe (RL), and caudate lobe (CL) were measured and analysed statistically to evaluate cirrhosis.TTP values of the LLL, LML, RL and CL were positively correlated with the Child-Pugh class of cirrhosis (r=0.452 to 0.55, all p0.05). PEI values of the LLL, LML, RL and CL, as well as the MSI of the CL and the MSD of the RL, were inversely correlated with the Child-Pugh class (r=-0.349 to -0.72, all p0.05). PEI values of the LLL and CL, or TTP values of the RL had the most area under receiver operating characteristic curve (AUC) of 0.99 for identifying the presence of liver cirrhosis. The PEI of the RL had the largest AUC of 0.975 and 0.78 for distinguishing the Child-Pugh class A of cirrhosis from class B-C and class A-B of cirrhosis from class C, respectively.Liver lobe-based DCE-MRI parameters are associated with the presence and Child-Pugh class of hepatitis B-related cirrhosis.

In this contribution, we examined and applied the redox chemistry of 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) radical cations (ABTS•+) with creatinine for the colorimetric and amperometric detection of urine creatinine. Colorimetric studies reveal that ABTS•+ is reduced and decololorized in the presence of creatinine, and its initial reaction rate is proportional to the initial concentrations of both ABTS•+ and creatinine. A colorimetric creatinine sensor was developed by entrapping ABTS into a chitosan film modified FTO substrate, followed by integrating a Nafion® overlayer to minimize the interferences from negative-charged biomolecules in urine, and applying an anodic pretreatment to generate ABTS•+. The developed colorimetric sensor exhibits promising sensing characteristics, including high accuracy for the detection creatinine in neat urine. On the other hand, the electrocatalytic scheme involving the electrochemical generation of ABTS•+ and reduction of ABTS•+ by creatinine forms the basis for the amperometric detection of urine creatinine. The developed electrochemical creatinine sensor, consisting of a Nafion® coated ABTS-CNT nanocomposite, also exhibits promising sensing characteristics, including high sensitivity (27.3 ± 0.5 μA cm-2 mM-1), low detection limit (∼11.0 μM), wide linear range (upto 21.3 mM), fast response time (t95) (

Graphitic carbon nitride (g-C3N4) has attracted considerable attention with regard to its use in photocatalytic solar hydrogen production by the splitting of water. High charge carrier recombination critically limits the photocatalytic activity of g-C3N4. Plasmonic metal nanoparticles that can generate localized surface plasmon resonance (LSPR) have been suggested to enhance the harvesting of visible light and to improve water splitting efficiency. However, direct contact between metal nanoparticles and g-C3N4 reduces the hydrogen generation efficiency owing to energy loss by Forster resonance energy transfer (FRET), which competes with plasmon resonance energy transfer (PRET). Decorating g-C3N4 with Ag@SiO2 core-shell plasmonic nanoparticles increases its photocatalytic ability. Tuning the size of the SiO2 nanogap can optimize the photocatalytic performance of g-C3N4/Ag@SiO2, which involves a trade-off between PRET and FRET. X-ray absorption spectroscopy (XAS) is utilized to investigate the electronic structure of g-C3N4 and its modulation with Ag@SiO2. In situ XAS reveals the dynamics of the charge carriers under solar illumination. Analytic results suggest charge redistribution, shifting of the conduction band, modification of the unoccupied states, and consequent improvement in photocatalytic activity by solar illumination. This work sheds light on the effect of LSPR on this photocatalyst with reference to its electronic structure.

The Powell's method was developed to determine the optimal stiffness and damping of multi-tuned mass dampers (MTMD) in offshore wind turbine (OWT) support structures under fatigue loads. Numerical examples indicated that the Powell's method results are always better than those using MTMD formulations. With the exception of the blade passing (3P) frequency, it was found in this work that a positive integer (n) multiple of the 3P frequency will also result in a large wind-induced vibration, which can be excited by the frequency of the first structural vertical rotation mode and will cause significant fatigue damage. The first translation mode TMD installed at the tower top is efficient to increase fatigue life at the tower and brace connections, but it cannot reduce fatigue damage at the column and brace connections below the platform. The second translation mode TMD can reduce fatigue damage resulting from large wave loads and thus increase the fatigue life of the braces and columns. The mode-3 TMD with a reduction in the 3(3P) vertical rotation can effectively increase the fatigue life of the braces and columns. Thus, the appropriate use of these TMDs can be effective for the fatigue problem of OWT support structures.

Multivariate statistical techniques of cluster analysis (CA) and discriminant analysis (DA) were applied in this study for the evaluation of water resource management strategies in high-tech industries, on the basis of the existing water use related data of 70 participating plants in Taiwan since 2011. The existing water use data were collected and transformed into detailed water balance charts, and the water use performance at individual plants was evaluated by three indices, namely the “processing water recovery rate”, the “plant water recovery rate”, and the “plant discharge rate”. Results from discriminant analysis showed that increase in the ratios of effluent recycled to pure water system (EPWR) and recycled to secondary water system (ESWR) had positive effects on achieving higher water use performance. On the other hand, process water consumption and ESWR were influential factors in discriminating samples with lower water use performance. The results also confirmed the finding from synergistic effect that improvement on both EPWR and ESWR contributed to the highest water use performance. Opportunities for water recycling in high-tech industries appears to be technically feasible, future efforts could usefully be undertaken to implement further investment on water-use efficiency and novel treatment techniques, and investigation on various reuse purposes.

In this study, a ternary nanostructured α-Fe2O3/Au/TiO2 film with integrating a crystalline α-Fe2O3 core, metallic Au nanoparticles (NPs), and an amorphous TiO2 overlayer is fabricated and examined as a photoanode for photoelectrocatalytic water splitting. Under simulated solar illumination, the as-prepared photoanode exhibits a four-fold increase (1.05 mA cm−2) in photocurrent density at 1.23 V versus reversible hydrogen electrode (RHE) relative to bare α-Fe2O3. Based on systematic investigations, it is proposed that Au NPs extract photoholes from the bulk of α-Fe2O3 core and then shuttle them to the outer TiO2 overlayer, and meanwhile, TiO2 overlayer efficiently captures and stores the photoholes and facilitates the hole injection into electrolyte. Thus, the remarkably improved photoelectrocatalytic water splitting performance of α-Fe2O3/Au/TiO2 photoanode is attributed to the significantly suppressed bulk and surface charge recombination due to the relayed pumping of the photogenerated charge carriers through the photoanode/electrolyte interfaces reconstructed by Au NPs and TiO2 overlayer.

In this study, we report a facile strategy to prepare a new class of red phosphorus (RP) decorated and doped TiO2 (A: anatase and B: TiO2(B)) nanofibers with boosted photocatalytic hydrogen evolution reaction (HER) performance from pure water. The optimized TiO2(B)/RP and TiO2(A)/RP heterostructure exhibits significantly enhanced photocatalytic performances, with HER rate reaching 11.4 and 5.3 μmol h−1, respectively. The optical absorption of TiO2 is significantly extended to the visible light region after decoration of RP. And more oxygen vacancies (VO) were introduced by phosphorus doping in the TiO2(B)/RP than TiO2(A)/RP. The theoretical calculations illustrate the formation of VO can decrease the ratio of effective masses of electron to hole, which gives rise to promoted photoinduced charge separation and transfer. These results suggest that the boosted photocatalytic HER performance should be mainly attributed to the synergetic enhancement in light harvesting and charge separation enabled by RP deposition and P5+ doping.

This research provides an analysis framework for offshore wind turbine (OWT) support structures subjected to seismic, wind, and wave loads using the finite element method with soil-structure interaction, and a conservative soil liquefaction analysis is developed. The NREL 5-MW jacket-type OWT under IEC 61400-3 is analyzed. The results indicate that seismic loads combined with wind and wave loads during power production often control the design, especially near the rated wind speed. For earthquakes with a peak ground acceleration (PGA) smaller than 0.32 g and the dominant period (Ts) smaller than 1 s, the increase in steel weight due to seismic loads is small, because the amplification of the seismic loads is not obvious. For PGA over 0.52 g, almost all the members are controlled by the seismic loads, and the increase in the steel design weight can be over 40%. This paper also indicates that first-mode tuned mass dampers for jacket-type support structure with deep piles are efficient to reduce the vibration coupled from wind, wave, and seismic loads even with 20-m soil liquefaction.

Building a decision support system (DSS) using small data sets usually results in uncertain knowledge, likely leading to incorrect decisions and causing a large losses. However, gathering sufficient samples for building a DSS often has significant costs in many cases. To solve this problem, a case study of a particular business decision-making procedure in which only small data sets are available is discussed. The learning accuracy for the modeling phase in the DSS was improved using the mega-trend-diffusion technique, which includes two learning tools: Back-propagation network and Bayesian network. The case study, a business diversification decision for an oil company, shows that the proposed technique contributes to increasing the prediction precision using very limited experience.