Bifunctional in situ polymerized nanocomposites for convective solar desalination and enhanced photo-thermoelectric power generation

Abstract

The inadequate supply of water and energy in remote areas poses a risk to human life, which can be overcome via the use of portable solar-driven evaporation setups. However, they involve energy-intensive techniques and salt-accumulation is still a significant barrier for large-scale solar steam generation applications. Herein, we report the preparation of bifunctional in situ-polymerized MnO₂@PPy nanocomposites (NCs) for nano-enabled solar evaporation followed by chemical convection and enhanced generation of photo-thermoelectricity. The novel evaporation structure design is composed of super hydrophilic MnO₂@PPy NC/two-phase crafted polyurethane wicks for the convective transport of water and polyethylene terephthalate (PET) foam for excellent thermal management. This work presents, for the first time, real-time experimental and simulated proof of a salinity gradient through convective flow, which is a promising solution for synchronous salt-rejection and intensified interfacial heat accumulation (42.8 °C) to generate vapor under 1 kW m⁻² at a rate of 1.69 kg m⁻² h⁻¹ and actually yield freshwater at a rate of 12.31 kg m⁻² per day. The state-of-art photo-thermoelectric performances revealed an enhanced output power density (P_out ∼ 12.3 W m⁻²) and open circuit current (I_out ∼ 61.3 mA) under 1 kW m⁻² solar irradiation, which are higher than that of other nanogenerators. More importantly, for the first time, numerical heat transfer and computational fluid dynamics (CFDs) simulations were successfully performed to study the salt-resistant mechanisms by computing the hot brine mass flux via chemical convection. Our work will further accelerate the distillate rate or zero liquid discharge phenomenon for the practical implementation of solar-driven seawater desalination and a clean source of energy generation.