A room-temperature synthesized NiFeCe2 electrocatalyst delivered a current density of 10 mA cm−2 at a cell voltage of 1.59 V when used as the electrolyzer.

In this study, the deep eutectic solvent (DES)-aided synthesis of γ-CoV 2 O 6 under modest reaction conditions using 1:1 choline chloride−malonic acid was reported. In the presence of DES, the reaction occurred at a lower temperature (500 °C) compared with that of the respective conventional solid-state synthesis of metal oxides and also with the calcination process involving the metal salts, thereby decreasing the overall formation energy. Differential scanning calorimetry revealed a 2-fold decrease in the endo effect of the thermodestruction of DES, which was observed at a low temperature. The structural pathway taken during the phase and morphology formation was investigated by in situ and ex situ X-ray diffraction (XRD) analysis, Raman spectroscopy, and scanning electron microscopy. The in situ XRD results confirmed the presence of high-temperature α-CoV 2 O 6 , which was finally converted to γ-CoV 2 O 6 . On account of the metal speciation in DES similar to the biotemplate, well-defined octahedral CoV 2 O 6 nanocrystals were obtained, which exhibited a remarkable OER catalytic activity at current density of 10 mA/cm 2 with an overpotential of a mere 324 mV, with excellent durability for greater than 24 h. Thus, a designer DES solvent with characteristics of biodegradability, cost-effectiveness, and renewability demonstrates potential for the synthesis of noble-metal-free oxygen evolution reaction (OER) catalysts, which allows the present synthesis route to fit well within the merits of green chemistry.

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