The higher-order structures of semiconductor-based photocatalysts play crucial roles in their physicochemical properties for efficient light-to-energy conversion. A novel perovskite SrTiO mesocrystal superstructure with well-defined orientation of assembled cubic nanocrystals was synthesized by topotactic epitaxy from TiO mesocrystals through a facile hydrothermal treatment. The SrTiO mesocrystal exhibits three times the efficiency for the hydrogen evolution of conventional disordered systems in alkaline aqueous solution. It also exhibits a high quantum yield of 6.7 % at 360 nm in overall water splitting and even good durability up to 1 day. Temporal and spatial spectroscopic observations revealed that the synergy of the efficient electron flow along the internal nanocube network and efficient collection at the larger external cubes produces remarkably long-lived charges for enhanced photocatalysis.

The performance of semiconductor materials in solar water splitting and other applications is strongly influenced by the structure-related dynamics of charge carriers in these materials. In this study, we assessed the trapping, recombination, and surface reactions of photogenerated and electrically injected charges on specific facets of the promising visible active photocatalyst BiVO 4 by using single-particle photoluminescence (PL) spectroscopy. Evaluation of the electric-potential-induced PL properties and the PL response to charge scavengers revealed that the visible PL bands observed during visible laser irradiation originate from radiative recombination between holes trapped at the intraband states above the valence band and mobile (free or shallowly trapped) electrons. Furthermore, the trapped holes are preferentially located on the lateral {110} facets of the BiVO 4 crystal, while the electrons are uniformly distributed over the crystal. The methodology described in this study thus provides us with a unique opportunity to explore whether or not the crystal faces affect the charge carrier dynamics in the photocatalysis and the photoelectrocatalysis.

The higher-order structures of semiconductor-based photocatalysts play crucial roles in their physicochemical properties for efficient light-to-energy conversion. An ovel perovskite SrTiO 3 mesocrystal superstructure with well-defined orientation of assembled cubic nanocrystals was synthesized by topotactic epitaxy from TiO 2 mesocrystals through af acile hydrothermal treatment. The SrTiO 3 mesocrystal exhibits three times the efficiency for the hydrogen evolution of conventional disordered systems in alkaline aqueous solution. It also exhibits ah igh quantum yield of 6.7 %a t3 60 nm in overall water splitting and even good durability up to 1day.T emporal and spatial spectroscopic observations revealed that the synergy of the efficient electron flowalong the internal nanocube network and efficient collection at the larger external cubes produces remarkably long-lived charges for enhanced photocatalysis.Transition-metal-based oxides sharing the perovskite structure are of scientific and technological interest for innovative applications owing to their remarkable physicochemical properties. [1] As ap rototypical perovskite,s trontium titanate (SrTiO 3 )w ith ac ubic crystal structure has attracted growing attention in the fields of electromagnetic devices [2] and solar energy conversion systems. [3] With the prospect of further reducing human energy usage and alleviating environmental pollution, [4] heterogeneous solid photocatalysts have been expected to exhibit promising solar-to-chemical energy conversion from water since 1972. [5] To promote the reaction efficiency,n umerous strategies have been developed, including band engineering, [6] morphology tailoring, [7] co-catalysts assistance, [8] and reaction environment optimization. [9] For instance,La-and Rh-codoped SrTiO 3 has been shown to work as an efficient hydrogen evolution reaction (HER) photocatalyst for overall water splitting under visible-light irradiation. [10] Wang et al. incorporated this material into photocatalyst sheet systems with an oxygen evolution photocatalyst (Mo-doped BiVO 4 )a nd aA ul ayer in which good electric contacts between the particulate semiconductors and Au are necessary to reduce the resistance and thus increase reaction efficiency. [11] Fort he development of more active SrTiO 3based photocatalysts,itiscrucial to seek aversatile route for the structure and property design. Novel hybrids of SrTiO 3 with TiO 2 have been developed that exhibit improved photoelectrochemical and photocatalytic performances, [12] and it may be anticipated that the efficiency and selectivity of their photocatalytic reactions are governed by the physicochemical characteristics of SrTiO 3 with tailored crystal facets and morphologies. [13] However,t here remain challenges that are relevant to the fabrication of the organized assembly of such structure-controlled nanoparticles up to the micrometer scale.With the development of mesocrystal family, [14] TiO 2 mesocrystals (TMCs), which consist of nanocrystal building blocks,h ave exhibited remarkably i...