In situ decorated Ni and Co in a CuBTC MOF for synergistic photocatalytic hydrogen generation

Abstract

In this study, a novel metal–organic framework (MOF), Co and Ni ion impregnated CuBTC, is synthesized and its photocatalytic hydrogen evolution reaction (HER) performance is investigated. The partial substitution of Cu²⁺ with Co²⁺ and Ni²⁺ ions in the catalyst is carried out and investigated to obtain critical insights into the underlying reaction mechanism. Morphological analysis revealed a well-defined octahedral structure for all photocatalysts. Among the synthesized materials, Co–Ni–CuBTC exhibited the highest HER rate of 23.9 mmol g⁻¹ h⁻¹, which is 6.6 times higher than that of pristine CuBTC. The photocatalyst characterization and its improved performance were corroborated using various physicochemical analyses including XRD, FTIR, XPS, and UV-DRS, and thermal stability assessments via TGA analysis. The Co–Ni–CuBTC composite exhibited a significant surface area and a prolonged average photoexcited charge lifetime of 1.03 nanoseconds, enhancing its photocatalytic HER efficiency. The structural stability of the Co–Ni–CuBTC photocatalyst is confirmed through post reaction SEM and XRD investigations. The photocatalytic mechanism study emphasizes the synergistic role of Co²⁺ and Ni²⁺ in the CuBTC framework with desirable photo redox properties for a superior HER. This work offers a promising strategy for uniformly incorporating multiple metal sites into organic frameworks to synergistically enhance photocatalytic performance.