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Developing high-performance overall water-splitting electrocatalysts working under alkaline condition is highly desirable but many challenges remain. Herein, the in- situ surface-derivation of Ni-Mo bimetal sulfides nanosheets on Co 3 O 4 nanoarrays, which supported on carbon fibers (Ni-Mo-S@Co 3 O 4 /CF) was designed and constructed. The as-prepared hybrid catalyst exhibits excellent electrocatalytic performance for both OER and HER under alkaline conditions, with only a small overpotential of 275 mV and 85 mV at a current density of 10 mA cm−2, respectively. Furthermore, the hybrid catalysts assembled full electrolyzer achieved a current density of 10 mA cm−2 at 1.57 V in an alkaline condition, without decay even after a durability test of 50 h. These results demonstrate that in-situ surface-derivation is a promising strategy for the design of efficient overall water splitting catalysts. Image 1 • The synergist effect of Ni/Mo with S can lower the overpotential of water splitting. • The bionic nanostructure provide ample electrochemical active surface. • Hybrid demonstrates a long as 50 h of overall water-splitting in alkaline media. [ABSTRACT FROM AUTHOR]

Abstract: Fluorapatite (FHAp) nanocrystals with various morphologies were synthesized through a hydrothermal process in the presence of three different chelating reagents: citric acid (CA), ethylenediamine tetraacetate disodium salt (Na2EDTA), and CA/Na2EDTA mixed chelating reagent. The morphology of FHAp nanocrystal is highly dependent on the pH value and nature of chelating reagent. In the case of CA, two main morphologies of FHAp nanocrystals were observed as pH value was varied from 3.6 to 10.0; while one-dimensional (1D) FHAp nanocrystals with hexagonal structure were always produced in the presence of Na2EDTA under different pH values. When the two chelating reagents mentioned above were simultaneously used, tuning the pH value resulted in not only a morphology change but also a structural transformation due to the synergistic effect of the chelating reagents. A possible mechanism for the formation of FHAp nanocrystals with various morphologies was discussed. [Copyright &y& Elsevier]