Synergy of solar interfacial evaporation and hydrovoltaics in MOF-303 hydrogel for simultaneous desalination and...

The growing mismatch between freshwater availability and energy demand presents a critical sustainability challenge. Solar-driven interfacial evaporation (SDIE) coupled with evaporation-induced hydrovoltaic generation (EIHG) holds promise for zero-carbon water-electricity co-production, but existing systems suffer from limitations in evaporation-power generation synergy, environmental adaptability, and output stability. Here, we present a hybrid hydrogel MOF-303/PVA-PPy gel (MPPG) embedding MOF-303 (zeta potential=-25 mV, specific surface area=783.34 m² g^-1) within a PVA-PPy hydrogel network to integrate SDIE and EIHG to produce water and electricity concurrently. The mechanism relies on synergistic effects between the photothermal-induced pressure gradients and the nanoconfined directional ion transport. MPPG nanochannel fluid transport modeling and experiments reveal environmental influences (ion concentration, wind, humidity, temperature) on electricity output. Under 1-sun irradiation in deionized water, MPPG achieves 3.02 kg m^-2 h^-1 evaporation and 0.552 V output, representing 11-fold and 4-fold increases in voltage and current density compared to bare PVA-PPy hydrogel. In artificial seawater, voltage further increases to 1.12 V, and collected freshwater meeting WHO drinking water standards. The system maintains 91 % performance over 72 h (<0.14 %/h degradation), and is scalable via series/parallel integration. This work provides an efficient, stable, and zero-carbon solution to simultaneously address freshwater scarcity and distributed energy supply challenges.