Pd Nanoparticles Supported on N-Doped TiO2 Nanosheets: Crystal Facets, Defective Sites, and Metal–Support Interactions Boost Reforming of Formaldehyde Solution for Hydrogen Production

To produce H2 from formaldehyde (HCHO), dehydrogenation offers an alternative approach to future hydrogen-based energy sources, but the unsatisfactory efficiency hinders its practical application. Here, ultrafine Pd nanoparticle (NP) decorated N-doped TiO2 nanosheets exposed with (001) facet catalysts (denoted as Pd/TiO2-x) have been prepared and exhibit superior H2 production performance from alkaline HCHO aqueous solution. Under our current conditions, the Pd/TiO2-x catalyst with a Pd loading of 1 wt % exhibits a H2 production rate of 183.77 mL/min/g, which is 1.75 and 3.66 times that of Pd/TiO2 and Pd NPs, respectively. Based on the results of Fourier transform infrared spectroscopy (FTIR), Raman, and liquid-phase electron paramagnetic resonance (EPR) spin-trapping experiments, the excellent H2 generation of Pd/TiO2-x can be attributed to the synergistic contribution among the reactive crystal facets, defective sites, and metal-support interactions in boosting the breakage of C-H bonds in HCHO, dissociation of H2O, and ultimately the formation of H2. This work is expected to provide a paradigm of an efficient catalyst to produce H2 from HCHO/H2O solution.