Facile synthesis of water-soluble Schiff-base polymers for photocatalytic H₂ production from water

Solar photocatalysis for splitting water to produce hydrogen has gained recognition as a promising technology for H2 generation. The linchpin of realizing this technology lies in developing effective, cost-effective, and practical photocatalysts. Polymeric photocatalysts have gained prominence compared to semiconductor ones, owing to their high structural versatility and tunable band gaps. In our current research, we synthesized two straightforward polymers (UP-1 and UP-2) using Schiff-base chemistry through a one-step hydrothermal process with urea (UA) and p-phthalaldehyde (PPA) as monomers. Specifically, UP-1 (UA:PPA = 1:1) features an imine (–C=N–) structure, whereas UP-2 (UA:PPA = 2:1) predominantly comprises an aminal (N–C–N) structure. The photocatalytic hydrogen production capabilities of UP-1 and UP-2 were assessed at room temperature, utilizing Pt as a cocatalyst and triethanolamine (TEOA) as an electron donor. Notably, UP-1 exhibits a H2 generation rate of 7.60 mL·h−1·g−1, significantly outperforming that of UP-2 (4.89 mL·h−1·g−1). It was postulated that UP-1’s imine structure possesses a superior conjugation, facilitating the generation of more photoelectron (e−)-hole (h+) pairs upon light irradiation and enabling smoother carrier migration compared to UP-2’s aminal structure. The work anticipates contributing to advancements in the generation of “gren H2” through solar photocatalysis using synthetically accessible polymers.