Accepted Articles e202401011
Research Article

ZnO with Different Morphologies Sensitized by Metalloporphyrins as Catalysts for H2 Production by Water Splitting under Sunlight

Shirley Nakagaki

Corresponding Author

Shirley Nakagaki

Universidade Federal do Parana Setor de Ciencias Exatas, CHEMISTRY, setor de ciencias exatas centro politecnico, BRAZIL

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João Felipe Stival

João Felipe Stival

Universidade Federal do Paraná, Chemistry, BRAZIL

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Camila Nunes Cechin

Camila Nunes Cechin

Universidade Federal de Santa Maria, Chemistry, BRAZIL

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Bernardo A. Iglesias

Bernardo A. Iglesias

Universidade Federal de Santa Maria, Chemistry, BRAZIL

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Ernesto Schulz Lang

Ernesto Schulz Lang

Universidade Federal de Santa Maria, Chemistry, BRAZIL

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Júlio Santos Rebouças

Júlio Santos Rebouças

Universidade Federal da Paraiba, Chemistry, BRAZIL

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First published: 04 October 2024

Abstract

In this work, zinc oxide with different morphologies and textural properties were prepared and sensitized with metalloporphyrins (MPs) aiming to improve its solar energy harvesting capability for H2 production by water splitting under sunlight (a 300 W Xe/Hg lamp). An anionic iron(III)porphyrin and a cationic manganese(III)porphyrin were immobilized on different ZnO solids predominantly by electrostatic interactions. In general, the prepared MP-free ZnO solid yielded modest catalytic results which had apparently no direct correlation with their textural properties or morphology. On the other hand, when these ZnO solids had iron or manganese porphyrin sensitizing them, their catalytic performances changed and a superior yield towards H2 production was observed in comparison to the pure ZnO solids, making evident the synergy achieved between these two components (ZnO and metalloporphyrins) for the prepared solids. It was also observed that the metalloporphyrins and the respective free-base ligand suffered redox reactions when used as homogenous catalyst in this reaction, which could influence their performances as catalysts. The same was not observed in the solids containing immobilized MP, suggesting some protective effect of the ZnO solids on the MP complexes upon immobilization probably due to interaction of the complexes with the ZnO matrix.