Interfacial evaporation-induced localized multi-field coupling enables efficient co-recovery of freshwater and nitrates

Recovering nitrate from surface water can help address interconnected environmental, resource, and energy challenges. In response, we have developed a bioinspired photothermal evaporation platform (BPEP) for the efficient co-recovery of low-concentration nitrate and freshwater. Through the evaporation-induced localized multi-field (flowing, concentration, temperature) enhancement effect, the BPEP achieves a high nitrate recovery capacity of 8510 g m^-2 under 1 sun illumination, approximately 6.7 times higher than under dark conditions. The flowing field is identified as the dominant contributor, accounting for nearly 80% of the total enhancement. In outdoor testing, BPEP demonstrates a high nitrate recovery of around 25.9 mg m^-2, with a daily water collection rate of about 8.46 kg m^-2. The extracted nitrate by BPEP can be further converted into nitrogen fertilizer via catalytic processes, thereby promoting plant growth. Overall, BPEP offers an integrated strategy to recover nitrate and freshwater, addressing pressing issues in global sustainable development.