Photothermal‐Responsive Aerogel‐Hydrogel Binary System for Efficient Water Purification and All‐Weather Hydrovoltaic Generation

Abstract

Abstract Hydrovoltaic generators (HVGs) convert abundant water energy into distributed electricity to promote the Internet of Things. Realizing low‐cost yet high‐performance HVG remains challenging, hindering its commercialization and application. Inspired by the xylem conduits in plants, which transport water and nutrients, an aerogel‐hydrogel binary‐component system (SHA‐HVG) is developed. It consists of a photothermal graphite‐doped polyvinylidene fluoride (G‐PVDF) aerogel, infilled with a thermosensitive wettability‐switchable sulfonic acid‐modified polyisopropylacrylamide hydrogel (S‐PNIPAM) by in situ polymerization, which significantly promotes water/ion transporting and boosts electricity output. SHA‐HVG demonstrates all‐weather high output by cooperating power generation mechanisms of thermosensitive hydrogel‐promoted surface photothermal evaporation during the daytime and sulfonic group‐enhanced ion concentration gradient at nighttime, resulting in efficient water desalination (2.75 kg m −2 h −1 ) and a 2669% increase in power density (56.86 µW cm −2 ) compared to single‐component HVG of G‐PVDF. SHA‐HVG is chemically stable and can be reactivated/recycled to improve its power generation efficiency to ∼130% by increasing its built‐in ionic environment. A marine/offshore cultivation system is demonstrated using an SHA‐HVG array, realizing an autonomous greenhouse for water desalination, self‐irrigation, and self‐powered environment monitoring. This work presents a cost‐effective HVG strategy for efficient seawater desalination and electricity harvesting, envisioning the development of distributed energy, smart agriculture, and offshore planting.