Mesoporous NiFe₂O₄ with Tunable Pore Morphology for Electrocatalytic Water Oxidation

Abstract

Mesoporous NiFe2O4 for electrocatalytic water splitting was prepared via soft‐templating using citric‐acid‐complexed metal nitrates as precursors. The mesopore evolution during thermal treatment was examined systematically giving insights into the formation process of mesoporous NiFe2O4. Detailed nitrogen physisorption analysis including desorption scanning experiments reveal the presence of highly accessible mesopores generating surface areas of up to 200 m2/g. The ability of the NiFe2O4 powders to perform electrocatalytic oxygen evolution reaction under alkaline conditions was investigated, highlighting the advantages of mesopore insertion. The most active samples reach a current density of 10 mA cm−2 at an overpotential of 410 mV with a small Tafel slope of 50 mV dec−1, indicating an enhanced activity that originated from the increased catalyst surface.

Magnetic NiFe2O4 Nanoparticles Prepared via Non‐Aqueous Microwave‐Assisted Synthesis for Application in Electrocatalytic Water Oxidation

“…[ 20 , 21 ] Thus, values for λ of 0.6 and 0.35–0.68 were reported for sol‐gel derived NiFe 2 O 4 nanomaterials by Atif et al. and Simon et al.,[ 22 , 23 ] which is then referred as a partially inverse spinel.…”

Magnetic properties and structural analysis on spinel MnFe2O4 nanoparticles prepared via non‐aqueous microwave synthesis

“…For this purpose, a magnetic hyperfine splitting in the Mössbauer spectrum is necessary. [8] However, this sextet splitting can only observed when the measurement temperature is lower than the respective blocking temperature (e. g. 32 K for the as-synthesized MnFe 2 O 4 nanoparticles), which is why no inversion parameter could be estimated from the room temperature data (Figure S9). Due to superparamagnetism at room temperature, a broad doublet with a quadrupole splitting of ΔE Q of 2.67 mm s À 1 was observed.…”

“…In principle, correlations of magnetic properties and cationic distributions in Fe‐based spinels can be investigated via 57 Fe Mössbauer spectroscopy. For this purpose, a magnetic hyperfine splitting in the Mössbauer spectrum is necessary [8] . However, this sextet splitting can only observed when the measurement temperature is lower than the respective blocking temperature ( e. g .…”

“…In the last decades, preparation of inorganic magnetic nanoparticles (MNPs) has received particular attention due to their widespread application range, including biomedicine, [1] imaging, [2] data-storage, [3] spintronics, [4] or homogeneous and heterogeneous catalysis. [5][6][7][8] Among the variety of available magnetic nanomaterials, the spinel ferrite class offers a significant saturation magnetization, a high electrical resistance, low electrical losses, and an outstanding chemical stability. [9] In addition, most of these materials can be prepared from earthabundant and inexpensive precursors.…”

Sol-gel-derived Ordered Mesoporous High Entropy Spinel Ferrites and Assessment of their Photoelectrochemical and Electrocatalytic Water Splitting Performance

“…The shorter calcined (10 min) sample showed a significantly lower overpotential of 420 mV at 10 mA/cm 2 as compared to the 500 mV at 10 mA/cm 2 for HEF-2h. For comparison, the HEF-10min sample possesses superior performance over the structurally related mesoporous NiFe2O4 (calcined at 550 °C, η > 570 mV at 10 mA/cm 2 ) [59] and Ni foil investigated under identical conditions (Figure S9 A).…”