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The construction of the highly active transition-metal phosphide/carbon-based electrocatalyst from metal-organic frameworks (MOFs) precursors is considered as an efficient approach. In this work, ZIF-67/GO precursors were firstly obtained by the in situ controllable growth of ZIF-67 nanocrystals on both surfaces of GO sheets. Then, a highly efficient bifunctional electrocatalyst CoP/Co@NPC@rGO nanocomposite was derived by the thermal pyrolysis of ZIF-67/GO precursors under N2 atmosphere and a subsequent phosphatization process. The structure and elemental composition of the ZIF-67/GO, Co@NPC@rGO, and CoP/Co@NPC@rGO nanocomposites were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and N2 ad-/desorption isotherms analysis. The Co@NPC@rGO‒800 nanocomposite exhibits a high Brunauer-Emmett-Teller (BET) surface area of 186.27 m2·g‒1, indicating that both micropores and mesopores existed. Subsequently, the electrocatalytic properties of the CoP/Co@NPC@rGO nanocomposites for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) were investigated by electrochemical measurements. The results suggest that the obtained CoP/Co@NPC@rGO‒350 nanocomposite only requires an overpotential of 127 mV to reach a current density of 10 mA·cm‒2 for HER in 1.0 mol·L–1 KOH solution. For OER, CoP/Co@NPC@rGO‒350 nanocomposite can reach a current density of 10 mA·cm‒2 at an overpotential of 276 mV, with a Tafel slope of 42 mV·dec−1, in the same alkaline aqueous solution, which is superior to RuO2. In addition, for both HER and OER, CoP/Co@NPC@rGO‒350 nanocomposite also shows impressive strong durability in alkaline aqueous solution. The outstanding performance can be attributed to the synergistic effect of coupled highly graphitized N-doped porous carbon and N-doped graphene. The as-prepared CoP/Co@NPC@rGO‒350 electrocatalyst is a promising candidate for overall water splitting in the alkaline solution. This development offers an attractive catalyst material based on MOF/GO composites. It is expected that the presented strategy can be extended to the fabrication of other composites electrode materials for more efficient water splitting.

Sn-doped, MgSiSn ( x = 0 to 0.6) bulk alloys were prepared using Mg and Sn ingots as raw materials by suspended induction melting combined with the spark plasma sintering method, and the effects of Sn doping on thermoelectric transport properties were studied systematically. The results showed that Mg site vacancies caused by evaporation during the reaction process were filled by excess Mg addition (108 wt.% of the stoichiometric ratio of MgSi). The resulting alloy samples were found to be single phase and relatively dense (above 98%). n-Type semiconducting characteristic of Sn-doped MgSiSn alloy was observed, and the electrical resistivity of all samples decreased with increasing temperature. The absolute Seebeck coefficient increased and the thermal conductivity was not changed significantly within the experimental Sn doping range. The dimensionless figure of merit ( ZT) for MgSiSn alloy reached its highest value of 0.25 at 400°C. [ABSTRACT FROM AUTHOR]

We review the historical, geological, tide-gauge, GPS and gravimetric evidence advanced in favour of, or against, continuing land uplift around Hudson Bay, Canada. We also reanalyse the tide-gauge and GPS data for Churchill using longer time series than those available to previous investigators. The dependence of the mean rate of relative sea-level change obtained from the tide-gauge record on the length and mid-epoch of the observation interval considered is investigated by means of a newly developed linear-trend analysis diagram. For studying the shorter-period variability of the tide-gauge record, the wavelet transform is used. The mean rate of land uplift obtained from GPS is based on a new analysis using IGS solutions of GFZ. To include the post-glacial land uplift, sea-level indicators from the Churchill region representing the relative sea-level history during the past 8000 years are also used. Finally, the values of the four observables are jointly inverted in terms of mantle viscosity. The optimum values are ~3.2 × 1020 Pa s and ~1.6 × 1022 Pa s for the upper- and lower-mantle viscosities, respectively. [ABSTRACT FROM AUTHOR]