Isabela C. Man

Universality in Oxygen Evolution Electrocatalysis on Oxide Surfaces

Trends in electrocatalytic activity of the oxygen evolution reaction (OER) are investigated on the basis of a large database of HO* and HOO* adsorption energies on oxide surfaces. The theoretical overpotential was calculated by applying standard density functional theory in combination with the computational standard hydrogen electrode (SHE) model. We showed that by the discovery of a universal scaling relation between the adsorption energies of HOO* vs HO*, it is possible to analyze the reaction free energy diagrams of all the oxides in a general way. This gave rise to an activity volcano that was the same for a wide variety of oxide catalyst materials and a universal descriptor for the oxygen evolution activity, which suggests a fundamental limitation on the maximum oxygen evolution activity of planar oxide catalysts.

Solar hydrogen production with semiconductor metal oxides: new directions in experiment and theory

An overview of a collaborative experimental and theoretical effort toward efficient hydrogen production via photoelectrochemical splitting of water into di-hydrogen and di-oxygen is presented here. We present state-of-the-art experimental studies using hematite and TiO(2) functionalized with gold nanoparticles as photoanode materials, and theoretical studies on electro and photo-catalysis of water on a range of metal oxide semiconductor materials, including recently developed implementation of self-interaction corrected energy functionals.

Tailoring the Activity for Oxygen Evolution Electrocatalysis on Rutile TiO2(110) by Transition‐Metal Substitution

The oxygen evolution reaction (OER) on the rutile MTiO2(110) (M=V, Nb, Ta, Cr, Mo, W, Mn, Fe, Ru, Ir, Ni) surfaces was investigated by using density functional theory calculations. The stability of different doped TiO2 systems was analyzed. The scaling relationship between the binding energies of OER intermediates (HOO* versus HO*) is found to follow essentially the same trend as for undoped oxides. Our theoretical analysis shows a lower overpotential associated with OER on the doped MTiO2(110) than on the undoped TiO2(110). The theoretical activity of Cr‐, Mo‐, Mn‐, and Ir‐doped TiO2 is found to be close to that of RuO2(110) for some of the configurations in consideration.

Volcano Relation for the Deacon Process over Transition‐Metal Oxides

We establish an activity relation for the heterogeneous catalytic oxidation of HCl (the Deacon Process) over rutile transition‐metal oxide catalysts by combining density functional theory calculations (DFT) with microkinetic modeling. Linear energy relations for the elementary reaction steps are obtained from the DFT calculations and used to establish a one‐dimensional descriptor for the catalytic activity. The descriptor employed here is the dissociative chemisorption energy of oxygen. It is found that the commonly employed RuO2 catalyst is close to optimal, but that there could still be room for improvements. The analysis suggests that oxide surfaces which offer slightly weaker bonding of oxygen should exhibit a superior activity to that of RuO2.

Volcano Relations for Oxidation of Hydrogen Halides over Rutile Oxide Surfaces

We investigate the heterogeneously catalysed oxidation of HX (X=Cl, Br and I) on the RuO2 (1 1 0) surface with DFT. We also solve a micro‐kinetic model of HX oxidation and compare oxidation activity at different coverages. We further establish linear energy relations for the reaction intermediates over a range of different rutile oxide surfaces. Based on the scaling relations, two descriptors are identified that describe the reactions uniquely. By combining scaling with the micro‐kinetic model, activity volcanoes for the three different oxidation reactions are derived. It is found that the commonly used RuO2 catalyst for HCl oxidation is closest to optimal for all three oxidation processes.