A Cu-C-i oxygen-evolution catalyst (C-i is inorganic carbonate) is prepared from of the abundant elements copper. They are generated in situ in carbonate solution (pH 10.25) with copper(I) complex under mild conditions (room temperature, atmospheric pressure, and near-neutral solution). The result indicates that the prepared Cu-C-i catalyst is amorphous. The average oxygen-evolution rate is 33.88 mu mol h(-1)cm(-2). An oxygen evolution overpotential of 263.8 mV is required at a current density of 1 mAcm(-2). Factors affected catalytic activity during water splitting, including temperature and type of electrolyte, are investigated. The phase, structure, morphology, composition, and catalytic activity of Cu-C-i catalyst are analyzed using a variety of characterization methods, namely, X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, high resolution transmission electron microscopy and electrochemical measurement. (C) 2014 Elsevier Ltd. All rights reserved.