SCIENCE CHINA Materials•2026•DOI: 10.1007/s40843-025-3762-9
The integration of interfacial photothermal conversion and hydrovoltaic effects into bifunctional evaporators offers a promising route to simultaneously address freshwater scarcity and energy demands. However, the development of low-cost bifunctional evaporators and elucidation of the underlying co-generation mechanism remain challenging. Here, we report a porous carbon derived from waste polyester via a metal-organic framework (MOF)-assisted carbonization strategy, which is subsequently fabricated into a bifunctional evaporator for freshwater and hydroelectricity co-generation. The porous carbon exhibits a high specific surface area of 904 m² g⁻¹, hierarchical micro- and mesopores, and abundant oxygen-containing groups. The resulting evaporator demonstrates broadband light absorption, localized thermal management, good hydrophilicity, and high flexibility. Under 1 sun illumination, it achieves an open-circuit voltage of 250 mV, a short-circuit current of 14 μA, and an evaporation rate of 2.34 kg m⁻² h⁻¹, ranking among the most efficient freshwater-hydroelectricity co-generators. The weakened hydrogen-bonding network reduces the water evaporation enthalpy to 1.7 kJ g⁻¹. Mechanistic studies, including molecular dynamics simulations, reveal that selective Na⁺ interaction induces differential ion migration rates, generating a streaming potential. Additionally, the photothermal effect enhances voltage output by promoting interfacial ion concentration gradients. Outdoor tests confirm stable voltage output of 250 mV and freshwater production of 2.34 kg m⁻². This work provides a scalable platform for fabricating advanced evaporators from waste plastics and unravels the co-generation mechanism, offering a sustainable strategy to mitigate freshwater and energy crises.
Chinese Journal of Environmental Engineering•2026•DOI: 10.12030/j.cjee.202511051
Photosynthetic bacteria (PSB) wastewater treatment technology is promising for simultaneous pollutant removal and resource recovery (e.g., single-cell protein, hydrogen). However, poor cell hydrophobicity and aggregation lead to low biomass retention and short sludge retention time, hindering engineering application. This study investigated the driving role and mechanism of upflow velocity as a key hydraulic selection pressure on PSB granulation under stepwise increasing organic loading rate (OLR). In laboratory up-flow photobioreactors (UPBR), comparative experiments were conducted with macro-index monitoring and micro-mechanism analysis. Results showed that under high upflow velocities of 3.00–6.30 m·h−1, PSB granular sludge with an average diameter of 285.58 μm and excellent settleability (sludge volume index, SVI = 22.73 mL·g−1) was successfully formed within approximately 60 days. Compared to the control, the granules in the experimental group were larger, with clear boundaries and compact structure, and significant enrichment of filamentous bacteria was observed. Mechanism analysis indicated that OLR provided nutritional driving force for microbial growth, while upflow velocity supplied high hydraulic shear force, physically screening and enriching settleable aggregates, and specifically inducing secretion of hydrophobic tryptophan-like proteins and humic acids (key extracellular polymeric substances, EPS). Additionally, core genera such as Xanthobacteraceae, possessing stress tolerance and EPS secretion functions, were enriched. This study reveals a chain mechanism of 'physical selection–biological response' centered on hydraulic selection, demonstrating that upflow velocity is a key controllable factor for PSB granulation, providing theoretical basis and technical pathway for solving PSB biomass washout and promoting resource-oriented treatment of high-strength organic wastewater.