Photothermal Application of Photovoltaic Silicon Waste in Preparing an Efficient Solar Water Evaporator

Solar water evaporation has been receiving attention in the field of desalination in recent years due to its potential of realizing water purification with sunlight irradiation serving as the only energy supply source. Silicon-based materials could functionalize photothermal heat generation under incident sunlight irradiation, resulting in their capability of being used in preparing solar water evaporators for desalination. Herein, photovoltaic silicon waste (PSW) produced as a byproduct from the cutting of silicon wafers was utilized for photothermal heat generation to prepare evaporators. An ice-templated channel structure was incorporated in PSW-based evaporators to ensure stable and efficient evaporation performance. After optimizing the category and content of components contained in PSW during the preparation of evaporators, the highest evaporation rate of 2.45 kg m^-2 h^-1 could be achieved by the PSW-based evaporator with solar-to-vapor efficiency exceeding 100% under 1.0 sun illumination. The 2-PSW2 evaporator could show a stable evaporation rate over 10-cycle or 8 h evaporation experiments. Purified water with 2.21, 12.27, 0.02, and 12.14 mg mL^-1 concentrations of Na⁺, Mg²⁺, K⁺, and Ca²⁺ could be produced based on the 2-PSW2 evaporator by desalinating actual seawater. Overall, the PSW-based evaporators reported in the present work introduce an effective design of solar water evaporator with efficient performance, and simultaneously proposed a promising approach for the upcycling of PSW to explore its underlying benefits.