A Cu20 cluster-based moisture-absorbing composite membrane for efficient photocatalytic hydrogen evolution in seawater under non-contact conditions

Abstract

Photocatalytic hydrogen production (PHE) from seawater is a critical pathway for overcoming resource constraints. However, salt ions present in seawater can significantly inhibit the photocatalytic hydrogen evolution activity and shorten the cyclic service life of photocatalysts. In this study, a copper-cluster-based moisture-absorbing composite membrane (Cu₂₀/FL/PVA) was designed and fabricated using polyvinyl alcohol (PVA) as the matrix and fluorescein (FL) as the photosensitizer. The composite membrane exhibits excellent moisture absorption properties and can drive the hydrogen evolution reaction under non-contact liquid water conditions. Based on these properties, the composite membrane is suitable for the PHE using seawater vapor, significantly inhibiting the poisoning effect of salt components in seawater on the photocatalyst. Compared with the FL/PVA membrane, the Cu₂₀/FL/PVA composite membrane with a 10% copper cluster loading exhibits a 3-fold enhancement in hydrogen production rate, reaching 1.46 mmol m⁻² within 4 hours. Furthermore, the composite membrane achieved stable hydrogen production in seawater for 8 h, with a final hydrogen production rate of 1.65 mmol m⁻². After the photocatalytic reaction, the composite membrane was confirmed to maintain excellent structural stability. This work provides important theoretical guidance and practical value for advancing the sustainable development of photocatalytic seawater hydrogen production technology.