Hematite (α-Fe2O3) is one of the most promising candidates as a photoanode materials for solar water splitting. Owing to the difficulty in suppressing the significant charge recombination, however, the photoelectrochemical (PEC) conversion efficiency of hematite is still far below the theoretical limit. Here we report thick hematite films (∼1500 nm) constructed by highly ordered and intimately attached hematite mesocrystals (MCs) for highly efficient PEC water oxidation. Due to the formation of abundant interfacial oxygen vacancies yielding a high carrier density of ∼1020 cm−3 and the resulting extremely large proportion of depletion regions with short depletion widths (<10 nm) in hierarchical structures, charge separation and collection efficiencies could be markedly improved. Moreover, it was found that long-lived charges are generated via excitation by shorter wavelength light (below ∼500 nm), thus enabling long-range hole transfer through the MC network to drive high efficiency of light-to-energy conversion under back illumination.

Herein, CeO2-modified PdAg alloy nanocomposites were anchored on mesoporous carbon, showing exceedingly high catalytic activity for HCOOH dehydrogenation at room temperature.

Dopant segregation, frequently observed in ionic oxides, is useful for engineering materials and devices. However, due to the poor driving force for ion migration and/or the presence of substantial grain boundaries, dopants are mostly confined within a nanoscale region. Herein, we demonstrate that core–shell heterostructures are formed by oriented self-segregation using one-step thermal annealing of metal-doped hematite mesocrystals at relatively low temperatures in air. The sintering of highly ordered interfaces between the nanocrystal subunits inside the mesocrystal eliminates grain boundaries, leaving numerous oxygen vacancies in the bulk. This results in the efficient segregation of dopants (~90%) on the external surface, which forms their oxide overlayers. The optimized photoanode based on hematite mesocrystals with oxide overlayers containing Sn and Ti dopants realises high activity (~0.8 μmol min−1 cm−2) and selectivity (~90%) for photoelectrochemical H2O2 production, which provides a wide range of application for the proposed concept.

Mesoporous silicas (MPSs) are widely used as host materials for applications involving molecular sorption, separation, storage, and (photo)catalysis. Herein we report single-molecule, single-particle approaches for exploring molecular diffusion and photochemical reactions in ruthenium (Ru) complex-modified MPS particles. Single-particle fluorescence recovery after photobleaching (FRAP) experiments revealed that Ru complexes are mobile in MPS with diffusion coefficients in the range of 10 0 -10 2 nm 2 s −1 , which vary among the particles and locations, and their diffusivity decreases with increasing amounts of sulfonated phenyl (SPh) groups, which act as adsorption sites for positively charged Ru complexes, on the silica surface.From emission lifetime measurements and photocatalytic activity tests using a fluorogenic probe at the single-particle, single-molecule levels, it was established that a series of reactions including quenching of excited Ru complexes by O2 and subsequent generation of  OH are completed within the same particle. By combining the above methods, a positive correlation between molecular diffusivity and reactivity was validated, suggesting the importance of wellordered nanochannels with optimized pore diameters and adequate environments for efficient heterogeneous (photo)catalysis.