Improving the Photoactivity of Porphyrin-Based Metal–Organic Frameworks via Constructing [Ce–O] Active Site and Vacancy

Abstract

Defect engineering of metal−organic frameworks (MOFs) is a versatile approach to tailoring their electronic structures and photocatalytic performance. Herein, Ce-based porphyrin MOFs (CMFs) featuring controlled structural defects were successfully prepared using a simple acid modulation strategy to drive the photocatalytic H 2 generation. The [Ce−O] unit serves as the active site via a ligand-to-metal charge transfer process, which has been confirmed by in situ XPS analysis. Abundant exposed coordinatively unsaturated Ce−O centers are beneficial for the adsorption and activation of water molecules, which is an important factor for improving the photocatalytic performance of the synthesized defective MOFs. In addition, optical and electrochemical experiments indicate that CMFs with more oxygen vacancies possess higher charge separation efficiency. As a result, the optimized CMF(Zn)-200 sample afforded high stability and activity in the H 2 generation (up to 1603.3 μmol•g −1 •h −1 under cocatalyst-free conditions) and tetracycline hydrochloride removal efficiency (97%), which was 8.45 and 97 times higher than that of pure meso-tetra(4-carboxyphenyl)porphine. This study demonstrates that effective structural modulation and defect introduction can improve the activity and stability of PMOF-based photocatalysts.