Ultrasonication construction of the nano-petal NiCoFe-layered double hydroxide: An excellent water oxidation electrocatalyst

Electrocatalytic water oxidation on CuO-Cu2O modulated cobalt-manganese layered double hydroxide

Layered double hydroxides (LDH) are potential electrocatalysts to address the sluggish oxygen evolution reaction (OER) of water splitting. In this work, copper oxide (CuO/Cu₂O) nanoparticles are integrated with cobalt-manganese layered double hydroxide (CoMn-LDH) to enhance their performance towards OER. The catalyst is synthesized by growing CoMn-LDH nanosheets in the presence of CuO/Cu₂O nanoparticles that were obtained by the calcination of the copper containing metal-organic framework (HKUST-1). The synthesized CoMn-LDH@CuO/Cu₂O electrocatalyst shows excellent activity towards OER with an overpotential of 297 mV at a catalytic current density of 10 mA cm^-2 and have a Tafel slope value of 89 mV dec^-1. Moreover, a slight decrease in the performance parameters is observed until the 15 h of continuous operation. We propose that the conductive strength of CuO/Cu₂O and its synergistic effect with the CoMn-LDH are responsible for the improved OER performance of the desired electrocatalyst.

Mixed Metal Oxide by Calcination of Layered Double Hydroxide: Parameters Affecting Specific Surface Area

Mixed metal oxide (MMO) is one of the widely utilized ceramic materials in various industries. In order to obtain high performance, the specific surface area of MMO should be controlled. Calcination of layered double hydroxide (LDH) is a versatile way to prepare MMO with homogeneous metal distribution and well-developed porosity. Although researchers found that the specific surface area of LDH-originated MMO was relatively high, it had not been systematically investigated how the surface area is controlled under a certain parameter. In this review, we summarized LDH-originated MMO with various starting composition, calcination temperature, and pore developing agent in terms of specific surface area and porosity. Briefly, it was represented that MMOs with Mg-Al components generally had higher specific surface area than Mg-Fe or Zn-Al components. Calcination temperature in the range 300–600 °C resulted in the high specific surface area, while upper or lower temperature reduced the values. Pore developing agent did not result in dramatic increase in MMO; however, the pore size distribution became narrower in the presence of pore developing agents.