A photothermal-driven hydrovoltaic-pyroelectric hybrid system for efficient energy harvesting and self-powered disinfection.

Capturing energy from water phase transitions holds great promise in emerging energy technologies due to its green, sustainable, and abundant nature. However, effectively harvesting this energy remains challenging, largely due to the inherently slow evaporation of water. Here, we present a high-performance hybrid generator that efficiently extracts water-phase transition energy through a multiscale structural design. The system integrates an arched multifunctional film with a polarized PVDF layer, enabling simultaneous photothermal, hydrovoltaic, and pyroelectric energy harvesting. Under optimized conditions, the device achieves a photothermal evaporation rate of ∼1.53 kg m^-2 h^-1 with a conversion efficiency of ∼96% enabled by rational microcomponent regulation, which is ∼30% higher than its planar counterpart. The hydrovoltaic output reaches a V_OC value of ∼1.13 V and an I_SC value of ∼6.46 μA, delivering a power density of ∼611 μW m^-2 that is 8.5-fold higher than previous designs under 1 sun illumination in seawater. The generator also yields a pyroelectric V_OC value of ∼143 V and an I_SC value of ∼694 nA, with a peak power density of ∼13.58 mW m^-2. Notably, these electrical outputs surpass earlier reports by >80%, attributed to enhanced interfacial temperature oscillations driven by the arched geometry. This platform reliably powers small electronic devices and enables a self-driven electrocatalytic system for seawater disinfection, achieving sodium hypochlorite production by coupling the generator with commercial Pt electrodes. Our multiscale design offers new insights for developing self-sustaining energy systems capable of harvesting and converting water-based energy for practical applications.