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Highlights • pH sensitive electrode developed based on voltammetry of vitamins B 2 and E. • Voltammetric response of vitamin B 2 sensitive to pH. • Voltammetric response of modified vitamin E insensitive to pH. • Voltammetric sensor does not require reference electrode with junction potential. • Sensor can be miniaturized and made disposable. Abstract The determination of pH using the conventional potentiometric glass electrode is widely practised in various fields ranging from academic to industrial environments. Recent research has focused on using various redox active organic and inorganic compounds as a basis of developing novel and miniaturized voltammetric pH sensors. This report describes the electrochemistry of such a sensor that is aimed to be disposable and based on a glassy carbon (GC) electrode drop cast with redox active vitamins. Voltammetric studies in deoxygenated buffered media revealed riboflavin (VB 2) and a vitamin E derivative (VEa) to be suitable as pH-dependent and independent electroactive compounds, respectively. Solid-state square-wave voltammograms of VB 2 and VEa that were concurrently drop cast on a GC electrode in various pH deoxygenated and oxygenated buffered media yielded Nernstian responses of –54.3 and –53.4 mV/ΔpH respectively, with the linear plot of the potential difference of VB 2 against VEa as a function of pH. Poor Nernstian responses were obtained in deoxygenated and oxygenated non-buffered media when the pH was above approximately 4. However, with the addition of a very low concentration of an acidic buffer into the reference solution, Nernstian responses of –50.0 and –50.9 mV/ΔpH were successfully achieved in deoxygenated and oxygenated weakly-buffered media, respectively. Furthermore, a strong correlation of voltammetric versus potentiometric pH highlights the suitability of the redox active vitamin compounds as a basis for a miniaturized voltammetric pH sensor. [ABSTRACT FROM AUTHOR]

Optimizing the hydrogen adsorption on electrodes is one of the most effective strategies to promote the hydrogen evolution reaction (HER). In recent years, cobalt phosphides (CoP) have been identified as a promising catalyst for HER in acid. However, the hydrogen adsorption on CoP is strong and a considerable overpotential has to be applied to enable HER. Here, we report a strategy to weaken the hydrogen adsorption on CoP through an electron deficiency in CoP induced by Au@CoP core/shell structure. A weakened hydrogen adsorption is confirmed by the density functional theory (DFT) calculation. Au@CoP gave an overpotential ( η ) of 160 mV at the current density of 1 mA cm −2 CoP , which is about 50 mV less than pure CoP. It also exhibited a turn-over frequency (TOF) value of 0.68 s −1 per active site at η  = 150 mV, which is more than 4 times higher than CoP. The strategy reported here holds potential to be extended to other electrodes for optimizing their hydrogen adsorption for HER. [ABSTRACT FROM AUTHOR]

Metal cluster-functionalized ionic liquids (ILs) exhibit promising characteristics for CO 2 conversion, however, progress in this area is currently limited due to the lack of understanding of the underlying reaction mechanisms involved. In this article the interaction of CO 2 with metal cluster-functionalized ILs is studied and provides key insights into the initial stages of CO 2 activation and subsequent conversion. The interaction of CO 2 with Au-Pd cluster-functionalized ILs is investigated using density functional theory (DFT) calculations based on the DFT-B3LYP approach and the mixed basis sets of 6-31+G (d, p) and LANL2DZ. It is found that single Au or Pd atoms can interact with ILs and results in a significantly stronger interaction of Au with ILs than that of Pd. More broadly it is also found that Au-Pd cluster-functionalized ILs can significantly enhance the interaction of CO 2 with ILs. Interestingly the interaction of CO 2 with Au-Pd cluster-functionalized IL is found to be highly dependent on the size and composition of the cluster. Among the systems studied, Au 1 Pd 2 -functionalized IL yields the strongest interaction with CO 2 . Our results highlight a non-monotonous behavior for the composition- and size-dependent interaction of CO 2 with Au-Pd cluster-functionalized ILs. It is proposed that these findings can provide a new roadmap for the design and development of metal cluster-functionalized ILs for CO 2 conversion applications. [ABSTRACT FROM AUTHOR]

The adsorption properties of nanoalloys can be tuned not only by size and morphology, but also by composition and chemical ordering. In this work, a density functional theory approach is applied to investigate the adsorption properties of neutral sulfur (S) on Ag–Au nanoalloys changing with the size, morphology, composition, and chemical ordering. It is proved that the adsorption strength of S on the Ag n and Ag n −1 Au ( n = 13, 55, and 147) clusters decreases with increasing the size, which is elucidated by the electronic contribution of p orbital of S. It is also verified that the adsorption strength of S on the Ag 42 Au 13 and Ag 55 clusters follows the order of cuboctahedral (Cubo) > icohedral (Ico) > decahedral (Dec), indicating that the Cubo-structured Ag 42 Au 13 and Ag 55 clusters possess high affinity toward S. In addition, it is found that the adsorption strength of S increases with increasing the content of Au for S on the Ag 42 Au 13 , Ag 54 Au and Ag 55 clusters changing with the composition. Moreover, it is also found that the adsorption properties of S on Ag 42 Au 13 can be tuned by changing its chemical ordering. Among these considered clusters, the Cubo-structured Ag 42 Au 13 cluster exhibits the best affinity toward S, due to its excellent electronic and geometric response to the adsorption of S. Our theoretical results are expected to provide new guidelines for designing and preparing effective and low-cost biosensor for detecting S based on the Ag–Au nanoalloys. [ABSTRACT FROM AUTHOR]

Automating the accurate classification of water in Landsat imagery will benefit many researchers conducting large-area multi-temporal analyses of the USGS archive. We propose that water index methods based on data normalised to surface reflectance, using thresholds optimised for a large selection of data, provide a simple yet accurate method for automated water classification across large regions. In order to select the best index for this task a comprehensive comparative analyses was required. We assessed the accuracy of seven water index methods for classifying water in 30 m resolution Landsat TM/ETM +/OLI imagery from eastern Australia. These indexes were the Automated Water Extraction Index for images with shadows ( AWEI shadow ) and without shadows ( AWEI no shadow ), tasselled cap wetness ( TCW Crist ), two variations of the normalised difference water index ( NDWI McFeeters and NDWI Xu ), a water index created using canonical variates analysis from top-of-atmosphere data ( WI 2006 ), and a new water index created with linear discriminant analysis from data processed to surface reflectance ( WI 2015 ). A wide variety of water (50,868), non-water (36,833) and mixed (16,499) validation pixels were selected from Landsat images across the states of New South Wales and Queensland. Water area and the colour of water and non-water features were determined for each validation pixel using coincident high resolution imagery and TM/ETM + reflectance. A single optimum threshold for classifying each index into water and non-water was determined using pure pixels. In general the WI 2015 , WI 2006 and AWEI shadow performed the best, with all indexes achieving overall accuracies of 95–99% for pure pixels, and 73–75% for mixed pixels. Omission errors were more common than commission errors, and water area was usually underestimated, especially where water was green-brown in colour, and/or where water bodies were small or had long perimeters with many mixed pixels. The accuracy of each index was highly dependent on the composition of the validation pixels, with no index performing best across all water and non-water pixel types. All indexes and thresholds were found to perform consistently across images from the TM, ETM + and OLI sensors, facilitating the automated classification of water to similar levels of accuracy for the growing archive of Landsat data. [ABSTRACT FROM AUTHOR]

Aeolian dust mantle soils are an important element of many landscapes in south-eastern Australia, though the age of these aeolian deposits has not been radiometrically determined. At Fowlers Gap in western New South Wales, surface cobbles of silcrete and quartz overlie a stone-free, aeolian dust mantle soil, which has a thickness of about 1.6m. The clay-rich aeolian dust deposit in turn lies upon a buried silcrete and quartz stone layer. Modelling in-situ cosmogenic 26Al/10Be concentrations measured in both the surface quartz stones and in the buried quartz layer of rocks, reveals that each has experienced a complex exposure-burial history. Due to the absence of quartz stones or sand at intermediate depths, our cosmogenic 26Al/10Be modelling was not able to determine a definitive mechanism of stone pavement formation and stone burial. Various scenarios of stone formation, transport, burial and exhumation were tested that constrain the age of the deposit to range from 0.9±0.2Ma to 1.8±0.2Ma, based largely on different assumptions taken for the time-dependency of the net sedimentation rate. This corresponds with the initiation of the Simpson Desert dune fields and the deflation of lakes in central Australia, which probably responded to the shift to longer-wavelength, larger-amplitude Quaternary glacial cycles at around 1Ma. Sensitivity analyses were carried out to identify those parameters which better constrained model outputs. Within model errors, which largely are the result of analytical errors in measured 26Al/10Be concentrations, all three competing theories of colluvial wash, upward displacement of stones, and cumulic pedogenesis are possible mechanisms for the formation of the surface stone pavement. [ABSTRACT FROM AUTHOR]

Medium resolution satellite-derived fractional cover estimates of bare soil (f BS), photosynthetic vegetation (f PV), and non-photosynthetic vegetation (f NPV) provide a powerful means to study arid ecosystem dynamics. This paper employed remote sensing estimates of f PV and f NPV from five case study sites from Australia's vegetated dunefields to observe (a) vegetation growth response to rainfall 'pulses' and subsequent transition to non-photosynthetic dormancy or senescence; (b) multiple time scales of antecedent climatic influence on vegetation cover; (c) the susceptibility of dunes to wind-blown sand drift during periods of low cover; and (d) the implications of image resolution choice when ground cover is heterogeneous. A spectral unmixing model for Australia's arid zone (termed 'AZN') was first developed by generating endmembers from a dataset of 1405 field surveys; Landsat time series estimates of f PV and f NPV were subject to a Seasonal-Trend decomposition by Loess (STL); Time series components were correlated with rainfall (P) and aridity at various accumulation periods; Fire maps were used to compare the climatic response of unburnt and burnt vegetation; Landform maps were used to isolate dune vegetation cover from the adjacent interdunes; and Landsat estimates of erodible area were compared with Sentinel-2 and WorlView-3 data. The new AZN model yielded Root Mean Square Error (RMSE) estimates of 14.5% (f BS), 6.5% (f PV) and 15.8% (f NPV) during cross validation. The AZN model also compared favourably to an existing continental-scale model when evaluated with independent reference data. Rainfall pulse responses of dune vegetation were detected initially as f PV , and 3–9 months later as a peak in f NPV. Components of f PV responded to P accumulated over 3–9-months (intra-annual), and 12–15-months (trend). The long-term build-up of f NPV , if left unburnt, was influenced by rainfall patterns over the preceding 45–114 months. Fires reduced both the depth and strength of antecedent rainfall's influence on vegetation, and vegetation was often more sensitive to P than to aridity. Erodibility (total cover <14%) and partial erodibility (cover <35%) were more common at the driest sites but did not universally match aridity levels, due to fires and differing vegetation. The targeting of dune crest regions highlighted their enhanced susceptibility to sand drift (in most cases), and, given their occurrence on relatively narrow ridges (~30 m), the importance of estimating cover at Landsat resolutions or better (e.g. Sentinel-2). • Arid fractional vegetation cover was unmixed from Landsat and Sentinel-2 data. • Pulse-reserve behaviour was detected as coupled peaks in green then dry vegetation. • Decomposed time series revealed multiple time scales of rainfall response. • 30 m resolution or less is required to detect wind erosion risk on vegetated dunes. [ABSTRACT FROM AUTHOR]

Hepatocellular carcinoma (HCC) represents one of the most prevalent cancers worldwide. Most patients are not surgical candidates, and transarterial embolization (TAE) has been used to treat patients with unresectable HCC. The purpose of this study was to identify factors that predict survival in patients treated with TAE at a Western medical center. Review of a prospective database identified 345 patients treated for HCC at University Hospital (Newark, NJ) between July 1998 and July 2004. Of these patients, 109 patients underwent TAE. Eleven of these patients were subsequently treated surgically and excluded from this study. Of the remaining 98 patients, demographic data and laboratory values were analyzed to predict survival by univariate and multivariate analysis. Several factors, including hepatitis status, Child-Pugh classification, serum alpha fetoprotein levels &#60;500 ng/ml, bilirubin &#60;2.0 mg/dl, prothrombin time &#60;16 seconds, platelet count &#60;200 × 109/l, albumin >3.5 gm/dl, and multiple treatments, predicted survival by univariate analysis. Serum alpha fetoprotein levels, Child-Pugh classification, and hepatitis status were found by multivariate analysis to independently predict survival. These factors may help to select patients with unresectable HCC who might benefit from TAE. [Copyright &y& Elsevier]

• Voltammetry of two types of drop cast CNTs from 3 dispersion solvents investigated. • Heterogeneous electron transfer rate not effected by type of CNT or solvent. • Analysis of current verses scan rate plots necessary to determine diffusion modes. • Cationic surfactant DDAB offers the best current responses for CNT modified electrodes. Quantitative analysis was performed on voltammetric data obtained from surface-modified electrodes that were prepared with functionalised carbon nanotubes (fCNTs) consisting of functionalised single-walled carbon nanotubes (fSWCNTs) and functionalised multi-walled carbon nanotubes (fMWCNTs). In order to obtain the optimum coating procedure, the fCNTs were dispersed in individual solutions of N -methyl-2-pyrrolidone, N,N -dimethylformamide and ethanol (EtOH), and drop cast onto glassy carbon (GC) electrode surfaces to become the surface-modified electrodes. Different classes of surfactants (positive, negative and neutrally charged) at varying concentrations were tested in the bulk solution to see how they affected the dispersion properties of the fCNTs as well as how they influenced the experimental heterogeneous electron transfer rates (k 0) measured via cyclic voltammograms (CVs) of the ferri-/ferrocyanide redox couple at the immersed film electrodes. The k 0-values measured at the fSWCNT/GCE and fMWCNT/GCE film electrodes were compared and the results indicated that the type of fCNTs and the%wt of the fCNTs used in the dispersion did not affect the rates of heterogeneous electron transfer. The effect of increasing bulk surfactant concentration was examined to determine the optimum current responses with the lowest voltammetric peak-to-peak separation (Δ E pp) values for the film electrodes. Thin layer diffusion and semi-infinite diffusion processes were found to be dominant at slow and fast scan rates, respectively. [ABSTRACT FROM AUTHOR]

Tree canopy density metrics (TCDM) derived from airborne lidar data are used in a range of crucial environmental monitoring, forestry and natural resource management applications. The derivation of spatially and temporally consistent TCDM, however, typically requires field calibration to account for differences in instrument/survey parameters. Lidar surveys with no coincident field measurements consequently will have an unknown error associated with TCDM limiting their application. In this study, we analysed an extensive set of lidar captures with coincident field data to determine the lidar TCDM that best match the canopy gap probability (P gap), foliage projective cover (FPC) and crown projective cover (CPC). Furthermore, we developed and evaluated models designed to reduce the bias introduced by variations in lidar instrument and survey acquisition parameters. The dataset incorporated 148 field sites (100 m diameter circular plots) coincident with 13 different lidar surveys between 2008 and 2015, distributed across a range of Australian forests and woodlands. The best lidar metric for 1 − P gap , achieving a root mean square error (RMSE) of 6.7% with 95% confidence intervals (CI) of 6.1–7.3%, was the proportion of all returns greater than a canopy height threshold (t canopy) of 1.5 m above ground (d all). The best metric for FPC (RMSE = 6.0%, CI = 5.3–6.7%) used the proportion of returns, weighted as the fraction of the number of returns recorded from each pulse (d weighted), with t canopy of 1.7 m. The best metric for CPC (RMSE = 7.0%, CI = 6.4–7.7%) was the proportion of 0.5 m pixels greater than 0.8 m above the ground, for an interpolated canopy height model (d interp). Overall bias for these metrics was low (~1%), however, the bias for individual surveys varied significantly. For example, for one survey d all consistently underestimated 1 − P gap with a bias of −8.3%, while a different survey consistently overestimated 1 − P gap with a bias of 3.8%. Elastic net regression models, using instrument, survey and plot parameters as predictor variables, were unable to consistently remove the bias. No relationships could be discerned between lidar parameters and the bias between lidar metrics and field measurements, potentially due to complex interactions between parameters, the spatial scale of the field plots, and uncertainties in field measurements and lidar attributes. Although the bias could not be modelled, the results provide metrics to derive P gap , FPC and CPC with less than 10% error from lidar surveys captured with similar parameters across Australia (>600,000 km2). • An extensive dataset of field plots and airborne lidar data was collated. • The effect of lidar parameters on canopy density metrics could not be modelled. • Standard canopy density metrics matched field measurements with low RMSE (~7%). [ABSTRACT FROM AUTHOR]

Ni-based nanoalloys have attracted many attentions for their magnetic and catalytic applications, but their stability and segregation properties still remain unclear. In this work, we systematically study the phase diagrams and segregation properties of Ni-M (M = Ir, Ru, Pt, Pd, Co, Au, Ag, Cu) nanoalloys by using both the theoretical models and atomistic simulations. Based on a nanothermodynamical theory, the phase diagrams of Ni-based nanoalloys (4 nm) with different morphologies are predicted and which show good consistence with the results from Molecular Dynamics (MD) simulations. Accordingly, based on the predicted phase diagrams, the phase stabilities of these Ni-based nanoalloys with the order of Ni-Ir > Ni-Ru > Ni-Pt > Ni-Pd > Ni-Co > Ni-Au > Ni-Ag ≈ Ni-Cu are predicted, which consists with previous available results. In addition, the general segregation trends for Ni-M (M = Ir, Ru, Pt, Pd, Co, Au, Ag, Cu) nanoalloys are predicted based on the proposed segregation rules by considering the surface energies and atomic sizes of metal atoms, which are in consistent with our Monte Carlo (MC) simulations and also previous results including simulations and experiments. This work highlights a simply and useful roadmap to predict the stability and segregation properties of Ni-based nanoalloys by combining both the theoretical models and atomistic simulations, which is of fundamental interest for both theorists and experimentalists. [ABSTRACT FROM AUTHOR]

Highlights: [•] Voltammetric methodology based on rocking disc is introduced. [•] With single-disc experiments uniform mass transport and hydrodynamic current enhancements are observed. [•] A predictive equation for the mass transport controlled limiting current is proposed. [•] For dual-semi-disc electrode modulation effects are demonstrated in generator–collector mode. [ABSTRACT FROM AUTHOR]

• Varying the N:C ratio affects the metabolic processes of R. palustris. • Biosynthesis, biohydrogen generation and exoelectrogenic activity were analysed. • A novel hybrid hydrogen-photoMFC was conceptualised. • A limiting N:C is beneficial for both biohydrogen and bioelectricity generation. The operation of bioelectrochemical systems (BESs) relies on the ability of microbes to export electrons outside of their cells. However, microorganisms are not evolutionary conceived to power BESs as most of the redox processes occur within. In this study, a low cost strategy equivalent to the one used to improve hydrogen production is employed to divert electrons from the metabolism to an electrode. Varying the ratio of nitrogen to carbon concentration (0, 0.20 and 0.54) determines what fraction of the electron flux is directed towards biosynthesis, biohydrogen generation and extracellular electron transfer. The ratio of 0.54 produced a higher specific growth rate while the ratio of 0.20 resulted in combined higher maximum specific hydrogen production and exoelectrogenic activity, translating into a maximum power density of 2.39 ± 0.13 mW m−2 in a novel hybrid hydrogen-photosynthetic microbial fuel cell. The current work sets a framework for the optimisation of R. palustris for bioenergy recovery. [ABSTRACT FROM AUTHOR]

To enhance efficiency, maintain performance and prolong the lifetime of a PEMFC functioning under diverse operating conditions, development of robust control strategies, which encompasses not only the ohmic loss region but also the activation and concentration loss regions, is indispensable. However, a reliable control strategy can be developed only with the information on the uncertainties in extrinsic and intrinsic input parameters in all the three regions of operation. To achieve this, we perform Monte Carlo simulation to correlate the simultaneous variation of 33 input parameters to the cell performance, water, and thermal management in all three regions of operation. Then, the critical parameters in each region of operation are ranked using sensitivity analysis. The catalyst parameters and operating cell potential have a significant influence in activation loss and ohmic loss regions, while the operating pressure and physical parameters affect the concentration loss region significantly. Subsequently, based on these sensitivities we develop reduced regression models to predict the cell performance, without having to solve the full set of equations, with at least 90% accuracy using machine learning techniques. Finally, we also statistically discuss the distribution of cell performance in all three regions of operation. • A mechanistic two-phase, two-dimensional, non-isothermal model for a PEMFC. • Monte Carlo simulations through simultaneous stochastic parameter variations. • Study of input parameter uncertainties in all three regions of operation: activation, ohmic and concentration loss regions. • Variations of stochastic parameters correlated with cell performance, water and thermal management. • Machine learning assisted reduced order models to predict cell performance in all three regions of operation. [ABSTRACT FROM AUTHOR]

Abstract An electrochemical method has been introduced to trigger the gelation process between catechol and chitosan. The process is based on the initial heterogeneous oxidation of catechol at an electrode surface with subsequent homogeneous polymerisation with chitosan. It is characterised using square-wave voltammetry (SWV) and large amplitude Fourier Transformed ac voltammetry (FTACV). The first employment of FTACV on this crosslinking process indicates a consistent response as SWV with a viscous gel being formed at the electrode surface. The application of bulk electrolysis at a carbon foam electrode, for scale up to form a homogeneous gel has been subsequently demonstrated. The resulting gel properties have been characterised by several techniques with its thermal stability at ca. 250 °C proving it an appealing candidate for various conditions. [ABSTRACT FROM AUTHOR]

The search for low cost and high activity bifunctional electrocatalysts for the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER) is a research priority in the development of rechargeable metal-air batteries. Manganese oxides are the current favorite, but their native activity needs to be substantially improved before they can be considered as the substitute of noble metals. We discovered phosphate modification as an effective strategy to increase the bifunctional oxygen activity of MnO 2 in ORR and OER. Specifically, the half-wave potential of phosphate-promoted α-MnO 2 (PMO) for ORR is 0.85 V vs. RHE, ∼70 mV more positive than α-MnO 2 and the same as the benchmark 20 wt% Pt/C catalyst. The OER potential to maintain 10 mA cm −2 of current density is 1.63 V, ∼40 mV more negative than α-MnO 2 and about the same as the benchmark 20 wt% Ir/C catalyst (1.60 V). The potential difference between ORR (at −3 mA cm −2 ) and OER (at 10 mA cm −2 ) is 0.79 V, a standard measure of bifunctional oxygen activity, notably surpasses the performance of α-MnO 2 (0.91 V) and the noble metals (0.95 V for Pt/C and 0.93 V for Ir/C). Additional electrochemical measurements and density functional theory calculations suggest that the promoted bifunctional activity of PMO is due to the dual-affinity of phosphate for O and OH groups, which assists O 2 /OH adsorption in ORR/OER. [ABSTRACT FROM AUTHOR]

Based on first-principles calculations, the hierarchical porous carbon/sulfur composites decorated by ionic surfactants (SDBS, SDS, CTAB) are firstly reported as the cathode materials for advanced lithium-sulfur batteries. The morphology, structure and electrochemical properties of the as-synthesized hierarchical porous carbon/sulfur composites are characterized by transmission electron microscopy (TEM), field-emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), nitrogen adsorption/desorption isotherm, Raman spectra, thermogravimetric analyses (TGA) and electrochemical tests. First-principles calculations reveal that lithium polysulfides (LiS and Li 2 S) can bind strongly to the O or N functional groups in the surfactants. Additionally, the hierarchical porous carbon, which derived from a very cheap and abundant cellulose bio-waste lotus seedpod shells, possesses a large specific surface area (2923.04 m 2 /g) and a high pore volume (1.4823 cm 3 /g). Hence, an outstanding initial capacity of 1138 mAh/g at a high discharge rate of 0.5 C with large areal mass loading of 3.2 mg/cm 2 and high sulfur contents of 86.55 wt% is obtained. Even after 100 cycles, the cathode material still represents an excellent cycling stability with reversible capacity of 1116 mAh/g at 0.1 C, low capacity decay of 0.16% per cycle and high coulombic efficiency of about 97%. [ABSTRACT FROM AUTHOR]

In this work, we present a systematic study on the electrochemical oxidation of C3 saturated alcohols (propanetriol, 1,2-propanediol, 1,3-propanediol, 1-propanol, and 2-propanol) on Co 3 O 4 in alkaline. Co 3 O 4 electrode was prepared by electrodeposition of Co(OH) 2 on graphite paper followed with a calcination step. The electro-oxidation of C3 saturated alcohols were investigated by a combination of cyclic voltammetry, multi-step chronoamperometry, and electrochemical impedance spectroscopy techniques in KOH solution. The electro-oxidation studies at Co 3 O 4 electrode followed an activity trend in the following order: propanetriol (GLY) > 1,2-propanediol (1,2-P) > 1,3-propanediol (1,3-P) > 1-propanol (1-P) > 2-propanol (2-P). The NMR analysis of the oxidized products showed that C-C bond cleavage occurred faster in alcohols having adjacent hydroxyl groups. X-ray absorption near-edge structure (XANES) spectroscopy study showed that there was no significant difference in Co oxidation state in the absence and the presence of glycerol. It was also found that the KOH concentration influenced electro-oxidation of those alcohols bearing secondary hydroxyl group (GLY, 1,2-P, and 2-P) more dramatically than that of those primary alcohols (1.3-P and 1-P). [ABSTRACT FROM AUTHOR]

Zero-valent iron has been intensively investigated in chemical reduction of nitrate in water, but the reduction requires acidic or weak acidic pH conditions and the product of the reduction is exclusively ammonium, an even more toxic substance. Zero-valent aluminum is a stronger reductant than iron, but its use for the reduction of aqueous nitrate requires considerably alkaline pH conditions. In this study, aluminum-iron alloys with an iron content of 10%, 20% and 58% (termed Al-Fe10, Al-Fe20 and Al-Fe58, respectively) were investigated for the reduction of aqueous nitrate. Al-Fe alloys were efficient to reduce nitrate in water in an entire pH range of 2–12 and the reduction proceeded in a pseudo-first order at near neutral pH conditions. The observed reaction rate constant (K obs ) of Al-Fe10 was 3 times higher than that of Fe and the K obs of Al-Fe20 doubled that of Al-Fe10. The nitrogen selectivity of the reduction by Al-Fe10, Al-Fe20 and Al-Fe58 was 17.6%, 23.9% and 40.3%, respectively at pH 7 and the nitrogen selectivity by Al-Fe20 increased from 18.9% at pH 2–60.3% at pH 12. The enhanced selectivity and reactivity of Al-Fe alloys were likely due to the presence of an intermetallic Al-Fe compound (Al 13 Fe 4 ). [ABSTRACT FROM AUTHOR]

The development of the catalyst with less Pt loading at the cathodes in proton exchange membrane fuel cell (PEMFC) is a promising way for promoting their commercialization. Here, by means of density functional theory (DFT) calculations, we screen the activity of binary and ternary platinum shelled electrocatalysts with inexpensive metals for the oxygen reduction reaction (ORR). Trends in the ORR activity of platinum shelled electrocatalysts are determined by DFT calculations of the adsorption strength of O on 55-atom nanoalloy clusters. For the binary Pt–M (M = Fe, Co, Ni, Cu) shelled electrocatalysts, the ORR activity follows the order of Pt 42 Fe 13 > Pt 42 Ni 13 > Pt 42 Co 13 > Pt 42 Cu 13 , meaning that Pt 42 Fe 13 is of the strongest ORR activity among these binary systems. Moreover, Pt 42 Fe 12 Cu 1 is found to be the most optimal catalyst for the ORR among these ternary Pt–M–N (M, N = Fe, Co, Ni, Cu) systems, which is expected to be validated in future experiments. Our results can provide useful insights for the design and development of binary and ternary platinum shelled electrocatalysts with inexpensive metals for the ORR. [ABSTRACT FROM AUTHOR]

Carbon paste electrodes modified by various dihydroxyquinone derivatives are investigated using both cyclic voltammetry and square wave voltammetry in order to ascertain suitability as voltammetric pH sensors. These electrodes show a Nernstian response to the change of pH, with a potential shift close to the theoretical value, 59.2 mV per pH unit at 298 K. Moreover, their capability of measuring the pH of the unbuffered solution with less than 5% error can be attributed to the occurrence of both inter- and intra- molecular hydrogen bonding present within the system. The efficacy of the compounds to be used as materials for solid state pH sensors is discussed. [ABSTRACT FROM AUTHOR]