Spatial charge separation achieved on the anisotropic facets of high symmetry SrTiO3 nanocrystals for highly efficient photocatalytic overall water splitting.

Plasmonic photocatalysis, stemming from the effective light absorbance and confinement of surface plasmons, provides a pathway to enhance solar energy conversion. Although the plasmonic hot electrons in water reduction have been extensively studied, exactly how the plasmonic hot holes participate in the water splitting reaction has not yet been well understood. In particular, where the plasmonic hot holes participate in water oxidation is still illusive. Herein, taking Au/TiO as a plasmonic photocatalyst prototype, we investigated the plasmonic hot holes involved in water oxidation. The reaction sites are positioned by photodeposition together with element mapping by electron microscopy, while the distribution of holes is probed by surface photovoltage imaging with Kelvin probe force microscopy. We demonstrated that the plasmonic holes are mainly concentrated near the gold-semiconductor interface, which is further identified as the reaction site for plasmonic water oxidation. Density functional theory also corroborates these findings by revealing the promotion role of interfacial structure (Ti-O-Au) for oxygen evolution. Furthermore, the interfacial effect on plasmonic water oxidation is validated by other Au-semiconductor photocatalytic systems (Au/SrTiO, Au/BaTiO, etc.).

Recent advances in particulate photocatalytic water splitting are reviewed and the pioneering works in scalable H2 evolution via photocatalytic OWS are presented.

As-synthesized malic acid carbon dots are found to possess photoblinking properties that are outstanding and superior compared to those of conventional dyes. Considering their excellent biocompatibility, malic acid carbon dots are suitable for super-resolution fluorescence localization microscopy under a variety of conditions, as we demonstrate in fixed and live trout gill epithelial cells. In addition, during imaging experiments, the so-called "excitation wavelength-dependent" emission was not observed for individual as-made malic acid carbon dots, which motivated us to develop a time-saving and high-throughput separation technique to isolate malic acid carbon dots into fractions of different particle size distributions using C reversed-phase silica gel column chromatography. This post-treatment allowed us to determine how particle size distribution influences the optical properties of malic acid carbon dot fractions, that is, optical band gap energies and photoluminescence behaviors.

The key to phase junctions for efficient charge separation is to consider both the phase alignment and interface structure.

Charge separation plays a crucial role in determining the solar-to-hydrogen conversion efficiency for photoelectrochemical water splitting. Of the factors that affect charge separation, the anisotropic charge transport property of semiconductors shows great potential in promoting charge separation, but it has received little attention. Herein, we report BiVO4 photoanodes with predominant [010] and [121] orientations and demonstrate a crystallographic-orientation-dependent charge separation of BiVO4 for solar water oxidation. We found that a [010]-orientated BiVO4 photoanode generated a photocurrent 2.9 times that of the [121]-orientated one, owing to the significantly improved charge separation. An in-depth investigation of the surface band bending by open-circuit potential and film conductivity by contacting atomic force microscopy reveals that the higher electron mobility along the [010] direction than that of [121] accounts for the improvement in charge separation. This work offers a fundamental insight into charge separation in anisotropic photoanodes for rational design of efficient photoanodes for solar energy conversion.

As wide range of light absorption and suitable redox potentials are prerequisites for photocatalytic water splitting, exploring new semiconductor‐based materials with proper band structures for water splitting still calls for longstanding efforts. In this work, a series of photocatalysts, bismuth tantalum oxyhalide, Bi4TaO8X (X = Cl, Br), with valence band and conduction band positions at ≈−0.70 and ≈1.80 eV versus the reversible hydrogen electrode (RHE), respectively, are found to be capable for both water oxidation and reduction under visible light irradiation. Using flux synthetic methods, Bi4TaO8X (X = Cl, Br) with microplatelet morphology can be successfully prepared. The photocatalyst based on these materials shows an apparent quantum efficiency as high as 20% at 420 nm for water oxidation. In addition, a Z‐scheme system coupling Bi4TaO8Br with Ru/SrTiO3:Rh is successfully achieved for overall water splitting with a stoichiometric ratio of H2 and O2 evolutions. This work demonstrates a new series of semiconductors Bi4TaO8X (X = Cl, Br) with the promising application in the field of solar energy utilization.

In the semiconductor photocatalyst system for overall water splitting, cocatalysts play crucial roles because they provide not only redox active sites but also charge separation function for photogenerated electrons and holes. In this work, we have investigated the cubic structured NaTaO 3 with six equivalent {001} facets to address the following two important questions: Can charge separation occur among the equivalent facets? How can photogenerated charges be separated on the equivalent surface for photocatalytic reactions? Charge location probe experiments by photodepsotion of noble metals and metal oxides show that no spatial charge separation occurs among the six equivalent facets of NaTaO 3 . However, observation of efficient overall water-splitting reaction upon loading of well-known cocatalyst NiO on the NaTaO 3 clearly demonstrates that photogenerated electrons and holes could still be well-separated. In-situ formation of Ni and NiO cocatalysts during the water-splitting process was revealed by X-ray photoelectron spectroscopy and synchrotron X-ray absorption spectroscopy, confirming the role of dual cocatalysts Ni/ NiO, where nickel serves as an electron trap (catalytic sites for proton reduction) and NiO serves as a hole trap (catalytic sites for water oxidation). Such vicinal charge separation by dual cocatalysts leads to efficient overall water splitting.