Solar-driven Mn-Co3O4/NF dual-function evaporator integrating hydrovoltaic–galvanic effects for enhanced desalination and power generation

Abstract

Incorporating solar steam generation with the hydrovoltaic effect presents a promising approach to concurrently addressing water scarcity and energy challenges. However, realizing a high water evaporation rate while simultaneously maintaining substantial electrical output in a single device remains a formidable obstacle. Here, this study presents a novel hydrovoltaic and galvanic effects-coupled evaporation platform (HGEP) for dual-function applications in freshwater production and electricity generation from seawater. Coating urchin-like Mn-doped Co₃O₄ on inclined nickel foam (NF), the system achieves a stable evaporation rate of 1.77 kg m⁻²h⁻¹ in 3.5 wt% brine under 1 kW m⁻² irradiation with a 30° tilt angle. The inclined structure facilitates unidirectional ion transport by establishing a salinity gradient, effectively preventing salt deposition for up to 8 h. Moreover, integrating Zr-Al electrodes effectively combines the hydrovoltaic and galvanic effects, enabling the HGEP to deliver a stable open-circuit voltage of 1.0 V and a short-circuit current of 1.5 mA—over an order of magnitude higher than the pure hydrovoltaic effect (0.49 V, 0.15 mA)—and achieve a maximum power density of 0.8 W m⁻². This study presents an innovative solar-powered water treatment technology that simultaneously achieves water production and power generation