In this work, an efficient and stable photo-assisted electrocatalyst of N-doped CoNiOOH for overall seawater splitting are proposed. The doped N atoms triggered local contractions of lattice, thereby, promoted the morphologies of products to evolve from nanoflowers to nanowires (NWs), and the obvious electrocatalytic enhancements. Especially under the illumination of AM 1.5 G, the U30-NWs exhibited a photo-assisted cathodic current density from −2.0 to −4.0 mA cm −2 at −0.05 V vs RHE, and also an anodic stability for more than 48 hours in seawater . Our studies reveal that the doped N atom could accumulate more electrons than O atom, leading to the degradation of Co and Ni 3d and O 2p states on either side of Fermi level , thus a p-type feature with the widened band gap and improved UV–visible light absorption. Meanwhile, the corrosion resistance was thus improved due to the chemical stable N-Co(Ni)-N bonds. This work provides a practical strategy towards the H 2 production via photo-assisted electrocatalytic seawater splitting.
Tao Zhao,Dazhong Zhong,Genyan Hao,Guang Liu,Jinping Li,Qiang Zhao
The development of efficient and stable electrocatalysts is of great significance for improving water splitting. Among them, transition metal oxyhydroxides show excellent performance in oxygen evolution reactions (OER), but there are certain difficulties in direct preparation. Recently, Metal–organic frameworks (MOFs) as precatalysts or precursors have shown promising catalytic performance in OER and can be decomposed under alkaline conditions. Therefore, using a mild and controllable way to convert MOFs into oxyhydroxides and retaining the original structural advantages is crucial for improving the catalytic activity . Herein, a rapid electrochemical strategy is used to activate well-mixed MOFs to prepare Co/Ni oxyhydroxide nanosheets for efficient OER catalysts, and the structural transformation in this process was investigated in detail by using scanning electron microscope , X-ray diffraction, Raman, X-ray photoelectron spectroscopy and electrochemical methods . It is discovered that electrochemical activation can promote ligand substitution of well-mixed MOFs to form porous oxyhydroxide nanosheets and tune the electronic structure of the metal (Co and Ni), which can lead to more active site exposure and accelerate charge transfer. In addition, the change of structure also improves hydrophilicity , as well as benefiting from the strong synergistic effect between multiple species, the optimal a-MCoNi–MOF/NF has excellent OER performance and long-term stability. More obviously, the porous CoNiOOH nanosheets are formed in situ during electrochemical activation process through structural transformation and acts as the active centers. This work provides new insights for mild synthesis of MOFs derivatives and also provides ideas for the preparation of highly efficient catalysts.
Biaobiao Lu,Yaoxia Yang,Yu Zhang,RuiRui Zhang,Fuxing Zhou,Qingtao Wang,Wei Zeng,Dongfei Sun
The exploration of clean, environmentally friendly, efficient and economical metal electrocatalysts is becoming more and more in-depth, but catalyst activity and stability are still the main goals. Herein, a thin regular pentagonal rough nanosheet array (La-CoNiOOH@FeSe@NiSe/NF) grown on a three-dimensional porous conductive surface was designed and synthesized. The prepared electrode material exhibited good catalytic activity in 1 M KOH solution, required only 270 mV of overpotential to provide 10 mA cm−2 current density for the oxygen evolution reaction (OER), and showed excellent stability for at least 90 hours during the OER process. The characterization test results proved that the incorporation of La changed the surface electronic structure, optimized the interface, modulated the active site on the surface of the material, and exposed a large number of active sites, thus improving the activity and stability of the catalyst material. At the same time, such a rough surface also gives the material excellent wettability and anti-bubble adhesion, which is also a key factor in maintaining the catalytic activity and OER stability of the material. This method provides a new idea for developing an efficient and economical electrolytic hydroelectricity catalyst.
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