Photocatalytic hydrogen generation from water is an important solar-to-chemical conversion process, and is also a sustainable and environment-friendly generation approach for energy source of hydrogen. Herein, for the first time, we report the noble-metal-free CoPig-C3N4 hybrid as a photocatalyst for the highly efficient hydrogen generation by water splitting under visible light irradiation, whose hydrogen generation rate is similar to 131 times higher than that of pure g-C3N4, and is even better than that of Pt/g-C3N4. Based on the detailed analyses of photoluminescence (PL) spectra, UV-vis diffuse reflectance spectroscopy (UV-vis DRS), photocurrent-time (i-t) curves, and electrochemical impedance spectroscopy (EIS) Nyquist plots, the reason for the high efficiency of CoP/g-C3N4 is found to be its good absorption ability of visible light, highly effective separation and low recombination rate of photo-generated electron-hole pairs due to the addition of CoP to g-C3N4. (C) 2016 Elsevier B.V. All rights reserved.