Search

Hydrogen production from water splitting is a green and efficient technology for storing clean energy. Herein, cerium-incorporated Ni 2 P nanosheets are designed as trifunctional electrocatalysts to generate hydrogen by hydrothermal self-oxidation of surface nickel foam (NF) in pure water to in-situ form Ni(OH) 2 nanosheets, followed by incorporation of Ce and phosphorization. The prepared material exhibits excellent electrocatalytic performance in hydrogen evolution reaction (HER), oxygen evolution reaction (OER) and urea oxidation reaction (UOR). When the current density is 100 mA cm−2, the UOR potential of Ce-Ni 2 P is 1.473 V lower than that in the OER (1.731 V), suggesting a great potential to replace the sluggish OER for overall water splitting. Moreover, the Ce-Ni 2 P/NF can be applied to the electrochemical treatment of real urine electrolysis with similar performance to the urea electrolysis. Such remarkable performance is attributed to the incroporation of Ce with "Ce3+/Ce4+ redox pairs", which can not only provide abundant reactive sites by the charge transfer appearance of defect sites, but also offer an effective buffering space for the pre-oxidation process from Ni2+ to Ni3+. It is thus beneficial for overall water splitting and coupled urea electrolysis, providing a promising candidate for urine wastewater treatment and clean energy production. • Nanosheets are prepared by hydrothermal self-oxidation of NF in pure water. • Ce leads to the lattice distortion of Ce-Ni2P and generates abundant defects. • Such interactions between Ce and Ni2P promote HER and OER/UOR performance. • Ce-Ni2P/NF can be applied for urine wastewater treatment. [ABSTRACT FROM AUTHOR]

In order to achieve a broader absorption bandwidth with smaller reflection loss (RL) in electromagnetic absorber, nickel ions (Ni 2+ ) were employed to partially occupy the sites of cobalt ions (Co 2+ ) in BaCoTiFe 10 O 19 . Ni-doped barium hexaferrite (BaNi x Co 1 − x TiFe 10 O 19 ) powders were synthesized via the sol–gel combustion method. Subsequently, the microwave absorbing composites were prepared by mixing the BaNi x Co 1 − x TiFe 10 O 19 powders with the paraffin. As the doped Ni 2+ ions were in augment, the grain size of BaNi x Co 1 − x TiFe 10 O 19 decreased from 400 nm to 50 nm. Based on the electromagnetic parameters measured by the vector net-analyzer in the frequency of 0.5–18 GHz, it was found that the peaks of the complex permeability shifted to the high frequency region with the increase of the doped Ni. Moreover, the composite ( x = 0.4) possessed a maximum reflection loss (RL) of −47.49 dB at 13.28 GHz with a matching thickness of 2.0 mm. It also had a bandwidth below −20 dB ranging from 12.36 GHz to 18 GHz, which has great potentials applications in the high frequency fields of the microwave absorbing materials. [ABSTRACT FROM AUTHOR]

• 2D interconnected NiTe/NF nanosheets was prepared by one-step hydrothermal method. • Annealing temperatures have an effect on crystal phase change and HER performance. • It leads to a positive shift of the d-band center on non-stoichiometric Ni 2.86 Te 2. • The Ni 2.86 Te 2 /NF exhibits superior HER performance compared to NiTe/NF. The non-stoichiometric Ni 2.86 Te 2 /NF was prepared by hydrothermal method combined with annealing process. Experimental and theoretical results demonstrate that the transition of crystal phase structure from NiTe to Ni 2.86 Te 2 leads to a strong electronic interaction between tellurium and nickel accompanying with the positive shift of the d-band center, resulting in improving the HER activity compared to the NiTe/NF. [Display omitted] It is of great significance to develop low cost, high-efficiency and environment-friendly electrocatalysts for hydrogen evolution reaction (HER) from water splitting. Herein, nickel telluride nanosheets grown on Ni Foam (NF) with three different crystal phases (NiTe, Ni 2.6 Te 2 and Ni 2.86 Te 2) are fabricated by one-step hydrothermal tellurization followed annealing process. The non-stoichiometric Ni 2.86 Te 2 /NF exhibits superior electrocatalytic HER performance compared to the NiTe/NF and Ni 2.6 Te 2 /NF, which is comparable to the state-of-the-art 20 wt% Pt/C catalyst at high current density. The Ni 2.86 Te 2 /NF only requires an overpotential of 348 mV to drive the current density of 200 mA cm−2 in a 1.0 M KOH electrolyte. Similarly, The Ni 2.86 Te 2 /NF delivered current densities of 200 mA cm−2 at the overpotential of 279 mV in 0.5 M H 2 SO 4. Such excellent performance could be ascribed to the fast electron transfer and positive shift of d d-band center from its rich defective effect of crystal phase transition, as well as to the exposure of active sites provided by the two-dimensional nanosheets with large specific surface area. This work provides valuable insights for the rational modulation of the crystal phase on the nickel telluride for catalyzing HER. [ABSTRACT FROM AUTHOR]

Efficient hydrogen production by water electrolysis is primarily restrained by imperfect over-potential and poor reaction dynamics on oxygen evolution reaction (OER). Thermodynamically favourable urea oxidation reaction (UOR) is a class of promising routes for substituting sluggish OER and for coupling with cathodic hydrogen production because of smaller equilibrium potential (0.37 V) than that of OER (1.23 V). Herein, a versatile Ru-NiO/p-Ni catalyst was prepared through in-situ generating nickel hydroxide nanosheets on the surface of ordered porous Ni, then doping low Ru and annealing treatment. The optimized Ru-NiO/p-Ni displayed outstanding activity and stability towards hydrogen evolution reaction (HER), OER and UOR with potentials of −0.13 V, 1.57 V, and 1.39 V at 100 mA cm−2, respectively. Ru-NiO/p-Ni‖Ru-NiO/p-Ni can achieve 100 mA cm−2 in urea-aided water splitting at a voltage of only 1.58 V, which is prominently 170 mV smaller than the voltage of water electrolysis (1.75 V). The excellent electrocatalytic performance is owing to the outstanding inherent activity generated by cooperative effect of Ru and NiO, along with rich defect and active centre of Ru-NiO/p-Ni supplied by the large surface area of 3D porous structure. The formation of more rich Ni active species with a high valence through transport of electrons between Ru and Ni is favourable to promoting the dissociation of urea molecules, eventually improving UOR. Therefore, it can facilitate urea-aided water splitting, which provides a valuable strategy for constructing versatile catalysts for a cathodic energy-efficient hydrogen production coupled with other anodic oxidation reactions. [Display omitted] • Replacing OER with UOR is apparently energy-saving for hydrogen production. • Ru activates NiO nanosheets grown in-situ on porous Ni to obtain more active sites. • Electron transfers of Ru and Ni species significantly promotes HER/OER/UOR. [ABSTRACT FROM AUTHOR]

Lactoferrin (LF) was used to assist the synthesis of zinc ferrite (ZnFe 2 O 4 , ZFO) semiconductor photocatalysts in this study, and superparamagnetic ZFO nanocrystals with an average crystallite size ranging from 11.3 nm to 20.1 nm were successfully obtained via the hydrothermal method. It was found that LF was conducive to fast formation of ZFO nuclei, which resulted in remarkable crystallinity enhancement of the as-prepared ZFO nanocrystals. The saturation magnetization ( M s ) of the as-prepared ZFO crystals would be greatly improved with increasing the LF content, and the M s of the as-prepared ZFO crystals synthesized with 50 mg of LF (ZFO-50LF) could reach 19.9 emu/g, whereas the M s of the as-prepared ZFO crystals synthesized in the absence of LF (ZFO-0LF) was only 8.8 emu/g. In addition, although the specific surface area of ZFO-0LF nanocrystals (127.2 m 2 /g) was larger than that of ZFO-50LF nanocrystals (101.6 m 2 /g), and ZFO-0LF exhibited a higher absorption of methyl orange (MO) molecules in contrast with ZFO-50LF, but ZFO-50LF possessed a larger optical absorption coefficient, smaller band gap and higher photocatalytic degradation efficiency per unit area. After being irradiated under UV light for 3 h, ZFO-50LF almost could make MO molecules completely degrade. Therefore, the LF-assisted synthesized ZFO nanocrystals have a promising application prospect to be used as a new high-efficiency recyclable photocatalyst. [ABSTRACT FROM AUTHOR]