CuFeN/CNT composite derived from kinetically modulated urchin-shaped MOF for highly efficient OER catalysis

Abstract Most reported non-precious-metal catalysts for oxygen evolution reaction (OER) are composed of iron, cobalt, or nickel. Copper, on the other hand, is relatively neglected despite its versatility. In this paper, we describe a series of steps to enhance the OER efficiency of copper-based catalyst, including metal organic framework (MOF)-guided structure control, secondary metal doping, and nitridation. In particular, the effect of growth solvent on coordination kinetics and morphology of the precursor MOFs was studied in detail. The optimal MOF structure was further engineered with Fe doping followed by rapid microwave-assisted nitridation, resulting in CuFeN/CNT composite. Experimental results showed that all three engineering steps have significant impact on the enhanced OER efficiency. CuFeN/CNT composite with optimal Fe doping derived from urchin-shaped CuFeMOF exhibited a greatly enhanced OER performance comparable to that of precious metal catalyst, affording a current density as high as 236.3 mA at an overpotential of 420 mV (RuO2, 215.3 mA). Furthermore, excellent stability in alkaline media was observed during 1000 cycles and chronopotentiometric analysis for over 20 hours. We highlight that the entire synthesis protocol is environmentally benign and sustainable by employing microwave to enable rapid formation and conversion of the precursors with minimal energy consumption.