A three-dimensional flower-like Cu-based composite and its low-temperature calcination derivatives for efficient oxygen evolution reaction

A novel Cu-based composite with unique three-dimensional (3D) nanoflower-like morphology and mesoporous structure (abbreviated as Cu-NF) was developed, using zeolitic imidazolate framework-67 (ZIF-67) as precursor via facile Cu ion etching, followed by low-temperature calcination strategy. The mass ratio of Cu2+ to ZIF-67 played a key role in morphology control. Additionally, low-temperature calcination changed the chemical components of the active sites and improved the porosity for mass transportation with the original morphology preserved. Sample Cu-NF-300, calcined at 300 degrees C displayed the best oxygen evolution reaction (OER) performance among all the samples, with a small overpotential of 347 mV in 1.0 mol center dot L-1 KOH and a low Tafel slope of 93 mV center dot dec(-1) for OER. Significant improvement in the electrochemical activity is attributed to the 3D superstructure and lowtemperature calcination activation, which offer a simple synthetic strategy for the fabrication of Cu-based electrocatalysts for OER.