By resorting on first-principles dynamical simulations and supporting experiments, we present a systematic and detailed inspection of a new series of inhomogeneous photocatalytic RVO4 systems (R = Y, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu), where YVO4 is the most representative member. We evidenced a carrier separation, promoted by Pt acting as a cocatalyst, which allows for a clear understanding of the electronic properties of these inhomogeneous systems. These, in turn, are shown to be of crucial importance in enhancing the photocatalytic activity in the cases of water or methanol aqueous solutions. The presence of f electrons, acknowledged as essential for an optimal photocatalytic performance, is clearly rationalized and the possibility of using Lu, in view of its smaller ionic radius, to enhance hydrogen generation is disclosed. Experiments confirm that YVO4, GdVO4, and LuVO4 have a potentially much higher efficiency than compounds containing other rare earth lanthanides. Hence, we provide a comprehensive guideline for designing a new generation of photocatalysts possessing unprecedented efficiencies.

We extend here our inspection, via first-principles dynamical simulations supported by experiments, to the inhomogeneous photocatalytic RVO4 systems. At variance with our former paper, we limit the present analysis to the most promising photocatalysts (R = Y, Gd) for which the addition of a Ni-based cocatalyst provides the best activities. The specific role of Ni-based cocatalysts is elucidated, showing that a surface Ni doping, as opposed to a bulk one, is the most efficient way to enhance the catalytic activities of these compounds. This is a key step in the improvement of the photocatalysts and a roadmap to optimize the amount of Ni dopant needed for both hydrogen and oxygen generation.

InVO4 has aroused much interest because of its photo-catalytic property in the visible light range. Experimentally, it is hard to unravel the microscopic picture of InVO4 and the details of its electronic properties. We have thus performed first-principles band structure calculations of both the bulk and thin film of InVO4. The thin film was simulated by a surface slab model cleaved from the bulk and equilibrated via ab initio molecular dynamics simulations. We have compared the electronic structure properties with those of TiO2 that is the better known photo-catalyst. Our results show that the electronic structure of the InVO4 is quite sensitive to the atomic configuration of metal atoms around O, whereas that of TiO2 is not. In order to investigate the excitation levels, the quasiparticle energy structure of TiO2 has also been calculated via the GW.