Splitting the double layer into autonomous cells is essential during the photoemission from a metal into a solution. An emitted electron participates in the discharge of the double cell isolated from the other part of the interface. The work function of such an electron decreases by a value which is half of the quantity accepted for a single-particle emission. Comparing the new value with the experimental data shows that the interfacial photocurrent is produced by the secondary electrons which acquire the energy in collisions with the primary ones.