Synergetic experimental and DFT insights of energy band structures and photogenerated reactive intermediates are indispensable to design impurity-doped photocatalysts for photocatalytic environment remediation and solar fuels. Herein, despite the larger bandgap (Eg), Zn-doped BiOBr samples exhibited superior activity to BiOBr in the photocatalytic water splitting but adverse in photodegradation of Rhodamine B under visible-light illumination. Based on the spectral and electrochemical impedance characterisations and DFT simulations, the broader bandgap of Zn-doped BiOBr was explicitly assigned to more positive valence band maximum (VBM) and more negative conduction band minimum (CBM). The enhanced photocatalytic water splitting on Zn-doped BiOBr was assigned to the higher redox chemical potentials of charge carriers on respective CBM and VBM, suppressed back reaction and reduced recombination of photogenerated charge carriers. However, the reduced e-h + recombination on Zn-doped BiOBr cannot cancel the adverse influences of its weaker light absorption and dye-sensitisation effects, leading to slower RhB photodegradation.

Research Highlights The g-C3N4/TiO2 heterojunction nanoparticles are firmly immobilised on PAA/PTFE UFM;

Corresponding Authors: z.jiang@soton.ac.uk (ZJ), peter.edwards@chem.ox.ac.uk(PPE) Research Highlights  A rapid ultrasonication synthesis was adopted to prepare BiOBrxI1-x solid solutions;  Lattice parameters of the BiOBrxI1-x solid solutions strongly deviate from Vegard's law;  The nonlinear dependence of bandgaps on Br/I ratio are clarified;  Tuning I/Br ratios can tune both the VBM and CBM of the BiOBrxI1-x solid solutions;  The Bi-rich BiOBrxI1-x solid solutions are superior to BiOBr in photodegradation of RhB Abstract A series of visible-light-responsive BiOBrxI1-x solid solutions were prepared by a rapid and efficient ultrasonication synthesis and applied in photodegradation of Rhodamine B in aqueous solution. The detailed characterisations showed that the lattice parameters and their band structures of the BiOBrxI1-x solid solutions significantly deviated from the well-established Vegard's law for solid solution materials. The Mulliken electronegativity and valence band XPS analyses revealed that the substitution of Br by less electronegative iodine can simultaneously modulate the edges of conductance and valence band of the BiOBr, leading to nonlinear dependence of bandgap (Eg) on the halogen anion concentrations. Although the solid solution displayed superior RhB photodegration activity to BiOI, only Br-rich BiOBrxI1-x solid solutions (x>0.5) were more active than BiOBr and BiOI, with the optimal one is BiOBr0.75I0.25. The Brdependence of bandstructure and photocatalytic activity for the BiOBrxI1-x solid solutions as well as their rate-limiting radical species were also clarified based on experimental and theoretical analyses.

Abstract:The proper selection of transition metals and support is pivotal to the design of active and selective catalysts for maleic anhydride hydrogenation (MAH). Herein, the M/CeO 2−δ (M = Co, Ni, Cu, respectively) catalysts with pre-optimised metal loading of 10 wt % were prepared via a wet impregnation method and well characterized to corroborate their MAH performance with the properties of metal, support and the M/CeO 2−δ catalysts. The results revealed that the metal dispersion on the catalyst declines in the order of Ni/CeO 2−δ > Co/CeO 2−δ > Cu/CeO 2−δ , similar to the apparent activity for maleic anhydride (MA) transformation to succinic anhydride (SA). The hydrogenolysis of SA to γ-butyrolactone (GBL) occurs on Ni/CeO 2−δ and Co/CeO 2−δ only when the MA → SA transformation completing. The Ni/CeO 2−δ displays superior activity and selectivity to Co/CeO 2−δ in both MA → SA and SA → GBL reactions, while the Cu/CeO 2−δ and CeO 2−δ are both inert for SA → GBL hydrogenolysis. The MA hydrogenation to SA follows the first order kinetic law on the Ni/CeO 2−δ and Co/CeO 2−δ catalysts yet a more complex kinetic characteristics observed on the Cu/CeO 2−δ . The distinct catalytic hydrogenation behaviours of the M/CeO 2−δ catalysts are assigned to the synergism of dispersion and electronic configuration of the transition metals and oxygen vacancies.

catalysts were prepared using an impregnation method and employed in CO 2 dry reforming of methane under coking-favored conditions. The spent catalysts were carefully characterized using typical characterization technologies and inelastic neutron scattering spectroscopy. The bimetallic catalyst exhibited a superior activity and anti-coking performance compared to Ni/Al 2 O 3 , while the most resistant to coking behavior was Co/Al 2 O 3 . The enhanced activity of the Ni(Co)/Al 2 O 3 bimetallic catalyst is attributed to the reduced particle size of metallic species and resistance to forming stable filamentous carbon. The overall carbon deposition on the spent bimetallic catalyst is comparable to that of the spent Ni/Al 2 O 3 catalyst, whereas the carbon deposited on the bimetallic catalyst is mainly less-stable carbonaceous species as confirmed by SEM, TPO, Raman and INS characterization. This study provides an in depth understanding of alloy effects in catalysts, the chemical nature of coked carbon on spent Ni-based catalysts and, hopefully, inspires the creative design of a new bimetallic catalyst for dry reforming reactions.