Search

Designing efficient non-precious electrocatalysts to boost water splitting for green energy is a worthy and crucial objective, while it is still an enormous challenge. Herein, single-phase Ni5P4 ultrathin porous nanosheets grown on Ni foam constructed using the three-dimensional single-phase hierarchical nanoflower Ni5P4 (defined as 3D SHF-Ni5P4) were assembled via a simple hydrothermal and phosphating process in an enclosed space. Benefitting from the special structure and morphology of 3D hierarchical porous ultrathin nanosheets, as well as their increasing number of active sites, the 3D SHF-Ni5P4 exhibited outstanding performance with low overpotentials of 180 mV and 106 mV for achieving a current density of 10 mA cm−2 in 1 M KOH toward both the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER), and the Tafel slopes were 54 mV dec−1 and 79 mV dec−1, respectively. The overall water separation setup, using 3D SHF-Ni5P4 as both the cathode and anode in 1.0 M KOH, achieved a current density of 10 mA cm−2 at a low voltage of 1.47 V, which surpasses that of the commercial Pt C/NF‖‖RuO2/NF (1.52 V). This work highlights an achievable strategy for the controllable fabrication of a 3D single-phase hierarchical nanoflower Ni5P4 electrocatalyst, constructed with ultrathin porous nanosheets containing plenty of active sites. It provided new insights into developing cost-effective single-phase electrocatalysts towards green energy by water splitting. [ABSTRACT FROM AUTHOR]

Ni-rich layered materials Li[Ni x Co y Mn z Al 1- x- y - z ]O 2 ( x > 0.8) are regarded as the competitive cathode for practical applications in lithium-ion batteries owing to the large discharging capacity. Nevertheless, the strong oxidation activity, the poor structure, and the thermal stability at the electrode-electrolyte interface would lead to much trouble, for example, inferior electrochemical properties and acute safety issues. To ameliorate the above problems, this work reports a strategy for the double modification of F - doping and LiNbO 3 covering in LiNi 0.88 Co 0.06 Mn 0.03 Al 0.03 O 2 cathode via using high-temperature calcining and ball-milling technology. As a result, the cathodes after F - doping and LiNbO 3 covering not only demonstrate a more stabilized crystal structure and particle interface but also reduce the release of high-activity oxygen species to ameliorate the thermal runaway. The electrochemical tests show that the LiNbO 3 -F - -modified cathode displays a superior rate capability of 159.3 mAh g -1 at 10.0 C and has the predominant capability retention of 92.1% in the 200th cycle at 25 °C, much superior than those (125.4 mAh g -1 and 84.0%) of bare cathode. Thus, the F- doped and LiNbO 3 -coated Ni-rich oxides could be a promising cathode to realize the high capacity and a stabilized interface.

Designing efficient non-precious electrocatalysts to boost water splitting for green energy is a worthy and crucial objective, while it is still an enormous challenge. Herein, single-phase Ni 5 P 4 ultrathin porous nanosheets grown on Ni foam constructed using the three-dimensional single-phase hierarchical nanoflower Ni 5 P 4 (defined as 3D SHF-Ni 5 P 4 ) were assembled via a simple hydrothermal and phosphating process in an enclosed space. Benefitting from the special structure and morphology of 3D hierarchical porous ultrathin nanosheets, as well as their increasing number of active sites, the 3D SHF-Ni 5 P 4 exhibited outstanding performance with low overpotentials of 180 mV and 106 mV for achieving a current density of 10 mA cm -2 in 1 M KOH toward both the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER), and the Tafel slopes were 54 mV dec -1 and 79 mV dec -1 , respectively. The overall water separation setup, using 3D SHF-Ni 5 P 4 as both the cathode and anode in 1.0 M KOH, achieved a current density of 10 mA cm -2 at a low voltage of 1.47 V, which surpasses that of the commercial Pt C/NF||RuO 2 /NF (1.52 V). This work highlights an achievable strategy for the controllable fabrication of a 3D single-phase hierarchical nanoflower Ni 5 P 4 electrocatalyst, constructed with ultrathin porous nanosheets containing plenty of active sites. It provided new insights into developing cost-effective single-phase electrocatalysts towards green energy by water splitting.

Structure design of photocatalysts is highly desirable for taking full advantage of their abilities for H 2 evolution. Herein, the highly-efficient TiO 2 {001}/g-C 3 N 4 (TCN) heterostructures have been fabricated successfully via an in situ ethanol-thermal method. And the structure of g-C 3 N 4 in the TCN heterostructures could be exfoliated from bulk g-C 3 N 4 to nanosheets, nanocrystals and quantum dots with the increase of the synthetic temperature. Through detailed characterization, the structural evolution of g-C 3 N 4 could be attributed to the enhanced temperature of the ethanol-thermal treatment with the shear effects of HF acid. As expected, the optimal TCN-2 heterostructure shows excellent photocatalytic H 2 evolution efficiency (1.78 mmol h -1 g -1 ) under visible-light irradiation. Except for the formed built-in electric field, the significantly enhanced photocatalytic activity of TCN-2 could be ascribed to the enhanced crystallinity of TiO 2 {001} nanosheets and the formed g-C 3 N 4 nanocrystals with large surface area, which could extend the visible light absorption, and expedite the transfer of photo-generated charge carriers further. Our work could provide guidance on designing TCN heterostructures with the desired structure for highly-efficient photocatalytic water splitting., Competing Interests: The authors solemnly declare no competing financial interests., (This journal is © The Royal Society of Chemistry.)