The photocatalytic reduction of maleic acid (MA) to succinic acid (SA)1 represents a valuable transformation in green chemistry2, as SA is a key platform chemical and a potential intermediate in greener alternative pathways toward nylon production. This study presents the synthesis, characterization and application as catalyst of a new Cu₂O/ZnO nanocomposite encapsulated in a polydopamine (PDA) shell, which plays a crucial role (thanks to its redox active properties) in overcoming the typical photodegradation of copper oxide under UV irradiation3. The catalyst was synthesized via a fast, eco-friendly, sonochemical route in water and tested in the photoreduction of MA under 254 nm UV light in water. When combined with a catalytic amount of sodium ascorbate, the system achieved up to 61% yield and 67% selectivity in SA over 72 h. PDA enhances catalyst durability and charge separation, while isotopic experiments confirmed that water—not ascorbate—is the hydrogen source, supporting a radical-mediated mechanism. The use of ZnO as a safer alternative to TiO₂, coupled with PDA's biocompatibility and the use of ascorbate as a green co-catalyst, demonstrates the potential of this system as a scalable, environmentally friendly route for value-added chemical production.

References
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[2]. Bellardita, M.; Virtù, D.; Di Franco, F.; Loddo, V.; Palmisano, L.; Santamaria, M, Chem. Eng. J. 2022, 431, 134131.
[3]. Raizada, P.; Sudhaik, A.; Patial, S.; Hasija, V.; Parwaz Khan, A.A.; Singh, P.; Gautam, S.; Kaur, M.; Nguyen, V.H., Arab. J. Chem. 2020, 13, 8424; Zindrou, A.; Belles, L.; Deligiannakis, Y., Solar 2023, 3, 87.