Facile integration of Ni-substituted polyoxometalate catalysts into mesoporous light-responsive metal-organic framework for effective photogeneration of hydrogen

Abstract

The integration of functional homogeneous polyoxometalate (POM) complexes into highly-dispersed and recyclable heterogeneous catalysts remains a substantially challenging research topic in solar-driven water splitting area. In this work, we report a facile and broad-spectrum impregnation method to construct two POM@MOF composites, Ni3PW10@NU-1000 and Ni3P2W16@NU-1000, by respectively incorporating a tri-Ni-substituted Keggin-type (K6Na[Ni3(H2O)3PW10O39H2O], denoted as K6Na-Ni3PW10) and a Wells-Dawson-type (Na4Li5[Ni3(OH)3(H2O)3P2W16O59], denoted as Na4Li5-Ni3P2W16) polyoxometalate into a mesoporous Zr-based metal-organic framework (NU-1000). Under minimally optimized conditions, the resulting POM@MOF composites can effectively photocatalyze hydrogen production with superior long-term stability and reusability, achieving a hydrogen evolving rate of 3482 and 13051 μmol g−1 h−1 for Ni3PW10@NU-1000 and Ni3P2W16@NU-1000, respectively. Various photophysical and spectroscopic analyses elucidated the possible photocatalytic mechanism and the catalytic difference between two POM@MOF composites.