Recently, the excitation of localized surface plasmon resonances in metal nanoparticles (NPs) has been exploited in membrane science (especially, membrane distillation) to overcome temperature polarization. However, the prohibitive costs of state-of-the-art plasmonic NPs such as Ag and Au have opened the quest of alternative materials. Here, we show that nanoscale photothermal effects activated by light irradiation on nanocomposite membranes made of a thin microporous coating of polydimethylsiloxane (PDMS) loaded with NiSe or CoSe NPs supported on polyvinylidene fluoride might be exploited to achieve crystallization of dissolved salts in brines. Explicitly, we demonstrate that the embodiment of the plasmonic NiSe and CoSe NPs is capable to originate an increase of the vaporization of the water from brine once the nanocomposite membranes are irradiated with sunlight, with the possibility to reach the supersaturation conditions, with the subsequent heterogeneous nucleation and crystallization of dissolved salts.