Fast Microwave Synthesis of Phase-Pure Ni₂FeS₄ Thiospinel Nanosheets for Application in Electrochemical CO₂ Reduction

Phase-pure spinel Ni2FeS4 nanosheets with a specific surface area of 80 m2 g–1 were successfully prepared via fast and energy-saving microwave-assisted nonaqueous sol–gel synthesis, starting from metal acetylacetonates and benzyl mercaptan as the sulfur source. Synthesized nanosheets were characterized thoroughly by X-ray diffraction including Rietveld refinement, X-ray photoelectron spectroscopy, energy-dispersive X-ray spectroscopy, electron microscopy, nitrogen and water vapor physisorption measurements, and thermogravimetric analysis coupled with mass spectrometry. Such noble metal free Ni2FeS4 nanosheets were successfully applied as electrocatalyst for the aqueous carbon dioxide reduction reaction, yielding selectively the syngas components hydrogen and carbon monoxide.