Defect engineering over anisotropic brookite toward substrate-specific photo-oxidation of alcohols

Generally adopted strategies for enhancing the photocatalytic activity are aimed at tuning the visible light response, the exposed crystal facets, and the nanocrystal shape. Here, we present a different approach for designing efficient photocatalysts displaying a substrate-specific reactivity upon defect engineering. The platinized, defective anisotropic brookite TiO2 photocatalysts are tested for alcohol photoreforming showing up to an 11-fold increase in methanol oxidation rate, compared with the pristine one, while presenting much lower ethanol or isopropanol specific oxidation rates. We demonstrate that the substrate- specific alcohol oxidation and hydrogen evolution reactions are tightly related, and when the former is increased, the latter is boosted. The reduced anisotropic brookite shows up to 18-fold higher specific photoactivity with respect to anatase and brookite with isotropic nanocrystals. Advanced in situ characterizations and theoretical investigations reveal that controlled engineering over oxygen vacancies and lattice strain produces large electron polarons hosting the substratespecific active sites for alcohol photo-oxidation

Well-formed, size-controlled ruthenium nanoparticles active and stable for acetic acid steam reforming

Mg(Al)O supported Ru and Rh catalysts with low loading of active metal (0.5wt.%) were tested in the steam reforming (SR) of acetic acid (AA) to hydrogen rich mixtures. Two synthetic procedures were adopted to deposit metal nanoparticles on support material: conventional impregnation from metal chlorides aqueous solutions and size-controlled metal nanoparticles (SCMNPs) deposition method. SCMNP derived Ru catalysts showed good performances fully comparable to standard Rh based systems. After 20h t.o.s. at reaction temperature of 700°C, steam-to-carbon ratio of 3 and weight hourly space velocity of 6h-1, Ru catalysts showed 100% conversion and hydrogen yield higher than 70%. The presence of well formed metal nanoparticles and the residual hydrotalcite present in the support play a determinant role in limiting the deactivation by coke deposition and by nanoparticles sintering

Effect of nature and location of defects on bandgap narrowing in black TiO 2 nanoparticles

he increasing need for new materials capable of solar fuel generation is central in the development of a green energy economy. In this contribution, we demonstrate that black TiO 2 nanoparticles obtained through a one-step reduction/crystallization process exhibit a bandgap of only 1.85 eV, which matches well with visible light absorption. The electronic structure of black TiO 2 nanoparticles is determined by the unique crystalline and defective core/disordered shell morphology. We introduce new insights that will be useful for the design of nanostructured photocatalysts for energy applications

Hierarchical hematite nanoplatelets for photoelectrochemical water splitting

A new nanostructured \u3b1-Fe2O3 photoelectrode synthesized through plasma-enhanced chemical vapor deposition (PE-CVD) is presented. The \u3b1-Fe2O3 films consist of nanoplatelets with (001) crystallographic planes strongly oriented perpendicular to the conductive glass surface. This hematite morphology was never obtained before and is strictly linked to the method being used for its production. Structural, electronic, and photocurrent measurements are employed to disclose the nanoscale features of the photoanodes and their relationships with the generated photocurrent. \u3b1-Fe2O3 films have a hierarchical morphology consisting of nanobranches (width 3c10 nm, length 3c50 nm) that self-organize in plume-like nanoplatelets (350-700 nm in length). The amount of precursor used in the PE-CVD process mainly affects the nanoplatelets dimension, the platelets density, the roughness, and the photoelectrochemical (PEC) activity. The highest photocurrent (j = 1.39 mA/cm2 at 1.55 VRHE) is shown by the photoanodes with the best balance between the platelets density and roughness. The so obtained hematite hierarchical morphology assures good photocurrent performance and appears to be an ideal platform for the construction of customized multilayer architecture for PEC water splitting