Promoting the Oxygen Evolution Reaction via Morphological Manipulation of a Lamellar Nanorod-Assembled Ni(II)-Pyrazolate Superstructure

Abstract

Nanoscale pyrazolate-based coordination polymers (CPs) are becoming increasingly popular as electrocatalysts owing to their customizable compositions and structures. However, using them for oxygen evolution reaction (OER) is highly challenging due to their unsatisfactory catalytic efficiency and relatively low stability. Herein, a simple one-step solvothermal process was employed for the fabrication of polycrystalline nickel-pyrazolate [Ni(Pz)] with an unusual lamellar nanorod-assembled microsphere morphology for the first time using ethanol as a green organic solvent via controlling other physical parameters. Meanwhile, the Ni(Pz) structure and morphology are investigated to derive its formation process following the different monomeric feed ratios relying on the metal/ligand interactions of CP. Shaping the Ni(Pz) electrocatalyst in well-oriented lamellar nanorod-assembled microspheres brings the advantage of porosity and high specific surface area, which expedites mass/charge transport and contact with the electrolyte as well as creates less tortuous pathways for charge distribution, thus improving the charge homogeneity. These high-class structural features and polycrystalline nature of Ni(Pz)-E-PVP facilitate amazing catalytic OER activity with a low overpotential of 290 mV at 10 mA cm–2 and a Tafel slope of only 94 mV dec–1 beyond the yardstick material (i.e., RuO2) in alkaline solution. A suite of measurements, entailing X-ray photoelectron spectroscopy and density functional theory calculations, suggest that the rich Ni–N4 moieties in Ni(Pz)-E-PVP are central species providing adsorption sites for OER intermediates. This facile protocol is prophesied to commence the imminent development of noble metal-free, effective, and low-priced electrocatalysts for OER.

Fabrication of well-aligned Co-MOF arrays through a controlled and moderate process for the development of a flexible tetrabromobisphenol A sensor

“…The metal ions and organic ligands in the reaction mixture are a key factor in the formation of the MOF structure. 20,61 Different ratios of the metal ion cobalt and the organic ligand 2-MIM were added to a certain amount of ultrapure water (0.25 : 8, 0.5 : 8, 1 : 8, 2 : 8, and 4 : 8). Fig.…”

Recyclable Ni-Containing Coordination Polymer as an Efficient Catalyst for the Synthesis of Oxindole and Quinoline Derivatives through the Borrowing Hydrogen Strategy

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