Palladium-decorated hierarchical titania constructed from the metal-organic frameworks NH2-MIL-125(Ti) as a robust photocatalyst for hydrogen evolution

Engineering metal-organic frameworks (MOFs) into hierarchical structured materials is crucial for providing a viable platform to construct efficient catalysts and broaden their applications in energy conversion and photocatalysis. Here, a simple and efficient solid-state pyrolysis of Ti-MOFs (NH 2 -MIL-125) sacrificial template combined with a photo-reduction process was developed to construct a series of hierarchical TiO 2 decorated with Pd nanoparticles. The hierarchical TiO 2 inherited the well-defined rounded rectangular submicron-tablet from NH 2 -MIL-125 precursor and was constituted of uniform anatase TiO 2 nanoparticles with an average size of 12   nm. Furthermore, the photocatalytic activity for the hydrogen production from water-methanol solution was improved by the optimization of the content of Pd as a cocatalyst, and the maximum was achieved with a Pd loading of 1.5%. The rate of H 2 evolution of 1.5% Pd decorated hierarchical TiO 2 (1.5% Pd/TiO 2 ) reached to 979.7   μmol   h −1 and 112.7   μmol   h −1 , under UV–vis light and simulated solar light, respectively. This unusual photocatalytic activity may be resulted from the positive synergetic effect of efficient light absorption, promoted separation and migration of photo-induced electron-hole carriers. The work highlights the potential of the MOFs-based hierarchical TiO 2 in the photocatalytic water splitting under solar light.