Polyelectrolyte Hydrogel‐Functionalized Photothermal Sponge Enables Simultaneously Continuous Solar Desalination and Electricity Generation Without Salt Accumulation

Abstract

Technologies that can simultaneously generate electricity and desalinate seawater are highly attractive and required to meet the increasing global demand for power and clean water. Here we develop a bifunctional solar evaporator that features continuous electric generation in seawater without salt accumulation by rational design of polyelectrolyte hydrogel‐functionalized photothermal sponge. This evaporator not only exhibits an unprecedentedly high water evaporation rate of 3.53 kg•m−2•h−1along with 98.6% solar energy conversion efficiency, but also can uninterruptedly deliver a voltage output of 0.972 V and a current density of 172.38 μA•cm−2 in high‐concentration brine over a prolonged period under one sun irradiation. Many common electronic devices can be driven by simply connecting evaporator units in series or in parallel without any other auxiliaries. Different from the previously proposed power generation mechanism, our study reveals that the water‐enabled proton concentration fields in intermediate water region can also induce an additional ion electric field in free water region containing solute to further enhance electricity output. Given the low‐cost materials, simple self‐regeneration design, scalable fabrication processes and stable performance, this work offers a promising strategy for addressing the shortages of clean water and sustainable electricity.This article is protected by copyright. All rights reserved

Amphiphilic Janus patch-grafted hydrogels for salt-rejecting solar water desalination

“…36,37 Recent studies found that the high ionic strength of polyelectrolyte sufficiently repelled and entrapped the ions that were entering the polyelectrolyte hydrogel network, favouring better salt ion rejection. 38,39 Yet, the water evaporation rate of these hydrogels was relatively low (less than 1.7 kg m −2 h −1 under one sun irradiation), [40][41][42][43] and reached only 2.4 kg m −2 h −1 even when photothermal materials were incorporated. [44][45][46] In this work, we propose a precise surface modication strategy to produce Janus hydrogels, in which the wettability of the hydrogel's surface can be regulated by tuning the surface coverage of ultrathin Janus patches (Scheme 1).…”

“…36,37 Recent studies found that the high ionic strength of polyelectrolyte sufficiently repelled and entrapped the ions that were entering the polyelectrolyte hydrogel network, favouring better salt ion rejection. 38,39 Yet, the water evaporation rate of these hydrogels was relatively low (less than 1.7 kg m −2 h −1 under one sun irradiation), 40–43 and reached only 2.4 kg m −2 h −1 even when photothermal materials were incorporated. 44–46…”