Interfacial Assembled Hydrogel Evaporator for Highly Efficient Thermal Management and Photothermal Coupled Water Splitting Reaction

Abstract This study presents the design and synthesis of a hydrogel composite optimized for Interface Solar Steam Generation (ISSG), merging photothermal MoS 2 hollow nanospheres, enhanced via polydopamine (PDA) coating for superior light absorption, with a polyvinyl alcohol (PVA) hydrogel matrix. The composite achieves a photothermal conversion efficiency of 95.6% at the interface, highlighting its effectiveness in solar energy harvesting. Under 1 kW m⁻ 2 solar irradiance, remarkable evaporation rates of 5.41 kg m⁻ 2 h⁻¹ (pure water) and 5.07 kg m⁻ 2 h⁻¹ (seawater) are recorded, alongside conversion efficiencies of 93.7% and 90.8%. Outdoor testing confirms a steady freshwater production at 3.11 kg m⁻ 2 h⁻¹. Incorporating the photothermal evaporation coupled with water splitting for hydrogen production, this system effectively mitigates the corrosive effects of chloride ions typically encountered in seawater, ensuring the integrity of the catalyst and thereby maintaining a high hydrogen production rate of 45.5 mmol m⁻ 2 h⁻¹. It exemplifies a sophisticated approach to balancing thermal dynamics and water transportation in solar evaporation technology. By demonstrating the feasibility of concurrent efficient photothermal evaporation and catalytic hydrogen production, this research introduces a pivotal strategy for enhancing the practicality and versatility of ISSG systems, thereby advancing sustainable energy and water treatment solutions.