Using readily available renewable resources i.e. solar energy and seawater to secure sustainable fuel and freshwater for humanity is an impactful quest. Here, we have designed solar thermal collector nanocomposites with Ag that possess efficient photothermic properties for highly targeted interfacial phase transition reactions that are synergistically favorable for both catalysis and vaporization reactions. The photothermic effect arises from plasmonic metal nanoparticles exhibits localized interfacial heating which directly triggers surface-dominated catalysis and steam generation processes, with minimal heat losses, reduce thermal masses and optics implementation. The solar thermal collector nanocomposites are seawater and photo stable for practical solar conversion of seawater to simultaneously produce clean energy and water. Finally, a proof-of-concept all-in-one compact solar hydrogen and distillate production prototype demonstrates the viability of sustainable photothermic driven catalysis and desalination of seawater under natural sunlight. Meanwhile, the photothermal pyroelectricity and piezoelectricity capabilities are also demonstrated. A proof-of-concept for concurrent photothermal management and enhanced solar pyroelectric generation under a real outdoor environment is also validated.