Efficiency improvement of solar stills through wettability alteration of the condensation surface: An experimental study

•Condensation process plays a critical role in the efficiency of solar stills.•Wettability of condensation surface affected the condensation mechanism.•Titanium dioxide and silicon nanoparticles were coated on the condensation surface.•Nano-coating of condensation surface changed the surface wettability.•Wettability alteration of condensing surface increased the productivity by 10–35%.