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Vegetation concrete has been widely applied for the ecological restoration of bare steep slopes in short-term frozen and non-frozen soil regions in China. However, field experiments conducted in seasonally frozen soil regions have revealed decreases in the bulk density, nutrient content and vegetation coverage. This study aimed to clarify the evolution process and mechanism of the engineering properties of vegetation concrete under atmospheric freeze-thaw (F-T) test conditions. The physical, mechanical, and nutrient properties of vegetation concrete were investigated using six F-T cycles (0, 1, 2, 5, 10 and 20) and two initial soil water contents (18 and 22%). The results revealed decreases in the acoustic wave velocity and cohesive forces and an increase in the permeability coefficient of the vegetation concrete owing to F-T action. X-ray diffraction tests indicated that the decreased cohesive force was closely related to the overall decrease in the content of gelling hydration products in the vegetation concrete. Additionally, the contents of NH 4 +–N, PO 4 3–P and K+ in the vegetation concrete increased, whereas that of NO 3 −–N decreased. The loss rates of these soluble nutrients increased, indicating that the nutrient retention capacity of the vegetation concrete had decreased. Specifically, the decreased nutrient retention capacity was mainly related to the disintegration and fragmentation of larger aggregates due to F-T action. This study provides theoretical support for future research on improving the anti-freezing capability of ecological slope protection substrates in seasonally frozen soil regions. [Display omitted] • F-T action reduces acoustic wave velocity and cohesive force, increasing permeability coefficient. • XRD tests indicated decrease in cohesive force closely related to an overall decrease in gelling hydration products. • F-T action reduces nutrient retention capacity of vegetation concrete by disintegrating and fragmenting larger soil aggregates. • Theoretical support for improving anti-freezing capability of ecological slope protection substrates. [ABSTRACT FROM AUTHOR]

A simple and efficient strategy that takes advantages of the synergistic effect of microwave heating method and hydrothermal method is used to synthesize Ni 2 CoS 4 /graphene oxide (MH-Ni 2 CoS 4 /GO). Firstly, Ni 2 CoS 4 nanoparticles are observed to grow uniformly on the surface of GO. Then the obtained MH-Ni 2 CoS 4 /GO electrode is tested and it demonstrates ultrahigh specific capacitance of 2675.0 F g−1 at the current densities of 2 A g−1, fantastic stability of 95.0% even after 2000 cycles at 30 A g−1 and excellent rate capability of 89.7% with current density increasing from 2 A g−1 to 30 A g−1. Moreover, the assembled AC//MH-Ni 2 CoS 4 /GO asymmetric supercapacitor also delivers a good specific capacitance of 126.5 F g−1 at 0.5 A g−1, outstanding stability of 97.0% after 2000 cycles at 5.0 A g−1, and an ultrahigh energy density of 59.6 Wh kg−1 at power density of 497.6 W kg−1. This work provides an approach to synthesize electrode materials with superior excellent performances and it can be easily scaled up for practical applications in supercapacitors. [ABSTRACT FROM AUTHOR]

Water electrolysis is a prospective technology that can be applied to hydrogen production. Currently, there are many catalysts for water splitting. Cerium (Ce) can be a catalyst itself and it also can be a catalyst promoter due to its flexible coordination and excellent redox ability. Here we try to introduce Ce into FeCoP catalyst, which has been proved to a promising electrocatalyst toward water splitting. The ternary CeFeCoP was prepared by hydrothermal on nickel foam (NF). Then low temperature phosphating is followed. The CeFeCoP/NF shows an efficient electrocatalytic performance. The CeFeCoP/NF electrocatalyst requires overpotential of 298 ​mV at current density of 50 ​mA ​cm−2 for oxygen evolution reaction (OER), much lower than 323 ​mV of FeCoP/NF; and it demands an ultralow overpotential of 97 ​mV to deliver a current density of 10 ​mA ​cm−2 for hydrogen evolution reaction (HER) with respect to 194 ​mV of FeCoP/NF. Moreover, it presents quite smaller Tafel slopes of 114 ​mV dec−1 (OER) and 147 ​mV dec−1 (HER) compared to 153 ​mV dec−1 (OER) and 159 ​mV dec−1 (HER) for FeCoP/NF. When CeFeCoP/NF is used as a bifunctional electrocatalyst for water splitting, a cell voltage of just 1.55 ​V can be achieved at 10 ​mA ​cm−2, which is much lower than 1.67 ​V of FeCoP/NF electrolyzer. Furthermore, the stability of CeFeCoP/NF electrolyzer can maintain 90% after 10 ​h of chronoamperometry test, displaying an excellent durability. This outstanding performance of CeFeCoP/NF can be attributed to larger electrochemical specific area, easier charge transfer process, and facilitated Ce3+↔ Ce4+ transformation of CeO 2 after introducing Ce. Here, we will prepare CeFeCoP on nickel foam (NF) via a hydrothermal method followed by low temperature phosphorization. The synthetic process of CeFeCoP/NF is illustrated. [Display omitted] • The CeFeCoP was prepared by hydrothermal on nickel foam followed by low-temperature phosphorization. • The bifunctional CeFeCoP/NF exhibits a low overpotential of 97 ​mV at 10 ​mA ​cm−2 for HER and 298 ​mV at 50 ​mA ​cm−2 for OER in 1 ​M KOH, respectively. • A low voltage of 1.55 ​V is achieved at 10 ​mA ​cm−2 for overall water splitting. [ABSTRACT FROM AUTHOR]