RESUMO
To meet the requirements for industrial water splitting to generate hydrogen, it is urgent, but still quite challenging to develop highly active and stable electrocatalysts for large-current-density hydrogen evolution reaction (HER). Herein, Ru-incorporated NiSe2 (Ru-NiSe2 ) was designed and synthesized. The introduction of Ru results in the formation of hierarchically structured Ru-NiSe2 with large electrochemical active surface area, and well-modified electronic structure. As expected, the as-fabricated Ru-NiSe2 displays impressive HER activity in 1.0â M KOH, with a low overpotential of 180.8â mV to reach the current density of 1000â mA cm-2 . Ru-NiSe2 also presents outstanding long-term stability at high current densities, owing to its high intrinsic chemical stability, and strong catalyst-support interface. Notably, when performed at a certain current density of 1000â mA cm-2 , the overpotential increase after 90â h is only 13â mV. Such excellent HER performance of Ru-NiSe2 demonstrates its great potential for practical use in industrial water splitting.
RESUMO
La2MoO6:Yb3+,Er3+ upconversion (UC) micro-crystals with a tetragonal structure were fabricated through a modified sol-gel method. The samples are found to be spherical in shape with a diameter of about 300 nm. Upon excitation of 980 nm light, the UC emission spectra of the phosphors exhibit green and red bands corresponding to the characteristic transitions of Er3+ ions. As Yb3+ concentration rises, the green emission intensity increases and reaches the maximum at 2.0% Yb3+ content, while the ratio of green/red emission intensities (IG/IR) declines monotonically. Temperature sensing capability was studied employing the fluorescent intensity ratio technique from the thermally coupled levels 2H11/2 and 4S3/2 of Er3+ in temperature range of 293â¼533 K. It is interesting to find that Yb3+ concentration has influence on the absolute sensitivity SA, while the relative sensitivity SR is almost independent of Yb3+ content. Furthermore, excellent thermal stability and high temperature sensitivity is also demonstrated in the 2.0% Yb3+-doped sample with the obtained maximum SA and SR as high as 0.008K-1 and 1.093%K-1, respectively. The experimental results indicate that Yb3+/Er3+ co-doped La2MoO6 phosphors can be excellent candidates for temperature sensing applications.
RESUMO
Self-supported Ru-doped NiMoO4 (Ru-NiMoO4) is synthesized on commercial NiMo foam. The Ru-NiMoO4 exhibits extremely high performance for electrocatalytic hydrogen evolution with a small overpotential of 170.6 mV to afford a current density of 1000 mA cm-2, and excellent durability for 150 hours in alkaline solution.
RESUMO
Honeycomb-like ZnFe2O4@Ni3S2 hierarchical nanosheet arrays on Ni foam (NF) were fabricated via a combined hydrothermal and electrodeposition method. The electrode exhibits high oxygen evolution reaction (OER) activity with low overpotentials of 254 mV at 10 mA cm-2 and 290 mV at 50 mA cm-2, a small Tafel slope of 39.29 mV dec-1 and excellent durability in an alkaline electrolyte.
RESUMO
The introduction of acetate in the precursor of metal-organic frameworks (MOFs) turns the final product from MOFs to NiRu/Ni(OH)2. Followed by annealing treatment, the obtained NiRu/NiO catalyst exhibits high hydrogen evolution reaction (HER) activity with a low overpotential (18 mV at 10 mA cm-2), and a small Tafel slope of 43.3 mV dec-1 in alkaline electrolyte.