Photoelectrochemical reactions have been studied since the beginning of the 1970 for their promising ability of converting $CO_2$ to fuels and chemicals. The state of the art is focused on developing these reactions on solid electrodes which bring with them the issues linked to scarcity, instability and high cost. The European SoFiA project wants to exploit the unique self-assembling property of surfactants, and proton transport properties in soap films. The main goal is realizing an economical artificial photosynthetic membrane in form of stable soap film with engineered photocatalytic surfaces. In this thesis a 1D COMSOL simulation of a surfactant monolayer has been carried out with a view on showing the feasibility of the project by simulating the behaviour of the main parameters over an 8-hour period.