Porous　interfacial　solar　steam　generator　(ISSG)　has　emerged　as　a　promising　approach　for　sustainable　seawater　desalination　and　wastewater　purification　due　to　its　superior　evaporation　performance　compared　to　the　conventional　bulk-heating　evaporator.　The　porous　structure　of　ISSG　significantly　promotes　the　evaporation　rate　by　lowering　the　enthalpy　of　water　vaporization,　but　its　specific　role　in　this　rapid　interfacial　evaporation　process　has　not　been　thoroughly　explored　in　the　literature,　which　potentially　impedes　the　practical　application　of　ISSG.　In　this　study,　five　self-assembled　graphene-based　hydrogels　(SGHs)　with　varied　pore　structures　were　prepared　to　investigate　their　impacts　on　vaporization　enthalpy　using　differential　scanning　calorimetry　and　Raman　spectroscopy.　Among　these　hydrogels,　SGH-3　fabricated　at　a　graphene-oxide　concentration　of　3　mg·mL−1　achieved　an　impressive　net　evaporation　rate　of　2.33　kg·m−2·h−1　under　1-sun　irradiation.　Even　in　the　highly　saline　sample　(34.42　%　salinity),　SGH-3　maintained　a　relatively　high　evaporation　rate　of　1.78　kg·m−2·h−1,　while　the　salinity　of　treated　water　complied　with　the　international　guidelines　of　drinking　water　quality.　Experimental　results　highlighted　the　determinant　effect　of　porous　structure　such　as　porosity　and　microchannel　size　distribution　on　decreasing　the　vaporization　enthalpy.　For　SGH-3,　the　predominate　microchannels　in　the　5–15　μm　range　balanced　water　clustering　and　replenishing　and　thus　ensuring　a　continuous　high-efficient　evaporation　process.　These　findings　offer　valuable　insights　into　the　rational　structure　of　efficient　ISSGs,　broadening　their　application　in　sustainable　water　purification　processes.　©　2025　Elsevier　Ltd