Monodispersed metal sites are commonly considered as active centers that dominate the high catalytic activity and selectivity of a catalyst. Photocatalysis is a complex series of photophysical and electrocatalytic process, in which, it still remains challenges to obtain a well-defined profile on the functions of the monodispersed metal sites. Here we report that monodispersed aluminum (Al) metal sites are not active centers but they create abundant nitrogen non-metal active centers in carbon nitrides. Density functional theory (DFT) calculations show that Al metal sites serve as the bridges among isolated carbon nitride layers to establish diverse transfer channels for electrons, thus achieving rapid carrier separation. These findings provide a new perspective on understanding the important role of monodispersed metal sites for highly effective catalytic reactions.