CO₂ and water activation on ceria nanocluster modified TiO₂ rutile (110)

Abstract

Ceria nanocluster modification of TiO2 rutile (110): Ce3+ formation, reduced energy gap, and enhanced CO2 and water activation.

Modification of TiO2 with hBN: high temperature anatase phase stabilisation and photocatalytic degradation of 1,4-dioxane

“…In the current computational setup, DFT+U is implemented to yield solutions in which charges are localized, rather than delocalized over the entire system, as in standard DFT. Despite these shortcomings, inferences regarding the impact of the modification may be drawn by comparing the energies computed in the photoexcitation model across the different systems and, in particular, with reference to the unmodified anatase (101) surface [91][92][93].…”

“…For these ribbon models, the adsorption energy is computed as: To model photoexcitation, a triplet electronic state was imposed on the system; this forces an electron from the filled valence band (VB) to the empty conduction band (CB), leaving a hole in the VB. More details of this model are presented in the supporting information and in [90][91][92][93][94]. Charge localization is assessed via analysis of computed Bader charges [95], spin magnetizations and excess spin density plots.…”

Activation of Water on MnOx-Nanocluster-Modified Rutile (110) and Anatase (101) TiO2 and the Role of Cation Reduction

“…Figures 1A,B show the adsorption energies and relaxed atomic structures of the stoichiometric Mn 4 O 6 -nanocluster modifying the OH-r110 and OH-a101 surfaces. The large, negative adsorption energies indicate that the nanocluster-surface interaction is favorable and that the nanoclusters will be stable against desorption and aggregation (Fronzi et al, 2016b; Nolan et al, 2016; Fronzi and Nolan, 2017; Nolan, 2018; Rhatigan and Nolan, 2018a,b). For Mn 4 O 6 -OH-r110 (Figure 1A), three Mn ions are 4-fold coordinated and to each of these is bound a terminal OH.…”

“…These parameters correspond to surface areas per supercell of 13.120 × 11.896 Å and 10.312 × 15.255 Å for rutile (110) and anatase (101), respectively. The surfaces are separated from their periodic images by vacuum gaps of 20 Å, as used in our previous studies (Fronzi and Nolan, 2017; Schwartzenberg et al, 2017; Nolan, 2018; Rhatigan and Nolan, 2018a,b). Γ-point sampling is used and the convergence criteria for the energy and forces are 10 −4 eV and 0.02 eV −2 , respectively.…”

“…Considerations for tuning these systems for optimal performance include composition, surface termination, nanocluster size, and stoichiometry; all of which contribute to the light absorption properties, charge carrier mobility and surface reactivity. DFT simulations can be used to illuminate the properties underpinning experimental observations (Nolan, 2011a; Jin et al, 2012; Nolan et al, 2012; Iwaszuk et al, 2013) and to screen candidate materials worthy of further investigation (Park et al, 2009; Graciani et al, 2010; Nolan, 2011b, 2012, 2018; Iwaszuk and Nolan, 2013; Lucid et al, 2014; Nolan et al, 2014; Fronzi et al, 2016b; Rhatigan and Nolan, 2018a,b).…”