Aloysius Soon

To obtain insight into the structure and surface stoichiometry of copper-based catalysts in commercially important chemical reactions such as the oxygen-assisted water-gas shift reaction, we perform density-functional theory calculations to investigate the relative stability of low-index copper oxide surfaces. By employing the technique of ``ab initio atomistic thermodynamics,'' we identify low-energy surface structures that are most stable under realistic catalytic conditions are found to exhib

As a first step towards gaining microscopic understanding of copper-based catalysts, e.g., for the low-temperature water-gas shift reaction and methanol oxidation reactions, we present density-functional theory calculations investigating the chemisorption of oxygen, and the stability of surface oxides on $\mathrm{Cu}(111)$. We report atomic geometries, binding energies, and electronic properties for a wide range of oxygen coverages, in addition to the properties of bulk copper oxide. Through cal

Native defects in cuprous oxide ${\text{Cu}}_{2}\text{O}$ are investigated by using first-principles calculations based on density-functional theory. Considering the formation of copper and oxygen vacancies, antisites and interstitials, and a copper split-vacancy complex defect, we analyze the electronic structure and calculate their respective formation energies as a function of the change in Fermi level under both copper-rich and oxygen-rich conditions. We find that, under both growth conditio

As a first step towards a microscopic understanding of single-Pt atom-dispersed catalysts on non-conventional TiN supports, we present density-functional theory (DFT) calculations to investigate the adsorption properties of Pt atoms on the pristine TiN(100) surface, as well as the dominant influence of surface defects on the thermodynamic stability of platinized TiN. Optimized atomic geometries, energetics, and analysis of the electronic structure of the Pt/TiN system are reported for various su

The ternary chalcogenide, ZnIn2S4, is known to exhibit various polymorphic expressions: from the cubic spinel phase to various polytypic layered hexagonal structures, commonly known as α, β, IIa, and IIb. Notwithstanding numerous recent studies on the superior photocatalytic activities of hexagonal ZnIn2S4, it remains unclear how the polymorphic expressions in this material may influence its physiochemical properties (and thus their performance in actual photodevices). Thus, revisiting and addre

Controlling the stoichiometry and metastability in functional oxides is often the key to enhance their performance for a range of important oxide-based technological applications. In this work, using the recently developed meta-generalized-gradient approximation (GGA) and hybrid density functional theory calculations, we study both stoichiometric and substoichiometric (Magnéli) oxides of tungsten and molybdenum, focusing on their structural parameters, growth thermodynamics, and electronic struc

Using first-principles density-functional theory calculations, we investigate the advantage of using h-WO₃(and its surfaces) over the larger band gap γ-WO₃phase for the anode in water splitting. We demonstrate that h-WO₃is a good alternative anode material for optimal water splitting efficiencies.

Zinc nitride (Zn3N2) is a promising candidate for optoelectronics applications due to its high electron mobility and high electrical conductivity. It is also thought that Zn3N2 can be used as a starting material to achieve p-type conductivity in ZnO-based oxide homojunctions. In this work, the electronic structure of bulk Zn3N2 is studied using density-functional theory (DFT) with different approximations to the exchange-correlation functional, ranging from (semi-)local functionals to the quasip

We perform first-principles density-functional-theory calculations to determine the stability and associated physical and electronic properties of different adsorption phases of N on Cu (100) and Cu (110) substrates for coverages ranging from 0.125 to 1 monolayer (ML). For N on Cu (100), we consider adsorption in fourfold hollow sites while for N on Cu (110), we consider various adsorption sites including N-induced missing-row surface reconstructions and the surface nitridelike, ``pseudo-(100)''

In this work, we present density-functional theory calculations to investigate the surface properties of TiN as a function of surface orientation and termination, as well as the influence of surface defects for various surface defect concentrations. We calculate both the surface energies (including vacancy formation) as a function of the nitrogen chemical potential, and plot the first-principles derived equilibrium crystal shape (ECS) under different growth conditions. We find that surface defec

To expand the unchartered materials space of lead-free ferroelectrics for smart digital technologies, tuning their compositional complexity via multicomponent alloying allows access to enhanced polar properties. The role of isovalent A-site in binary potassium niobate alloys, (K,A)NbO₃ using first-principles calculations is investigated. Specifically, various alloy compositions of (K,A)NbO₃ are considered and their mixing thermodynamics and associated polar properties are e