Structure and electronic properties of transition-metal/Mg bimetallic clusters at realistic temperatures and oxygen partial pressures

Composition, atomic structure, and electronic properties of TM$_x$Mg$_y$O$_z$ clusters (TM = Cr, Ni, Fe, Co, $x+y \leq 3$) at realistic temperature $T$ and partial oxygen pressure $p_{\textrm{O}_2}$ conditions are explored using the {\em ab initio} atomistic thermodynamics approach. The low-energy isomers of the different clusters are identified using a massively parallel cascade genetic algorithm at the hybrid density-functional level of theory. On analyzing a large set of data, we find that the fundamental gap E$_\textrm{g}$ of the thermodynamically stable clusters are strongly affected by the presence of Mg-coordinated O$_2$ moieties. In contrast, the nature of the transition metal does not play a significant role in determining E$_\textrm{g}$. Using E$_\textrm{g}$ of a cluster as a descriptor of its redox properties, our finding is against the conventional belief that the transition metal plays the key role in determining the electronic and therefore chemical properties of the clusters. High reactivity may be correlated more strongly with oxygen content in the cluster than with any specific TM type.Comment: 7 pages, 5 figure

Mechanistic role of Cu co-catalysts in unassisted photocatalytic CO2 reduction using p-GaN/Al2O3/Au/Cu heterostructures

DFT-relaxed structures of Cu2O, CuO, and malachite with various surface facets, as well as their heterostructures with Au. It incorporates the DFT relaxed structure (.cif and.json file) used in the paper's title"Mechanistic role of Cu co-catalysts in unassisted photocatalytic CO2 reduction using p-GaN/Al2O3/Au/Cu heterostructures" with VASP 5.4.4 and employs the PBE +U exchange-correlation functional.</p

Interfacial engineering to modulate surface dipoles, work functions and dielectric confinement of halide perovskites via surface passivation

National audienceLead halide perovskites have attracted considerable interest owing to their rich physics and rapidly burgeoning applications in the field of optoelectronic devices. Therefore, an accurate theoretical description of the link between surface dipoles and the work functions, especially to understand the interface effects in this class of materials is of scientific and practical interest

Theoretical insights to tune the surface dipoles and work functions of halide perovskites

National audienceLead halide perovskites have attracted considerable interest owing to their rich physics and rapidly burgeoning applications in the field of optoelectronic devices. Therefore, an accurate theoretical description of the link between surface dipoles and the work functions, especially to understand the interface effects in this class of materials is of scientific and practical interest. Herein, we briefly introduce our methodology that accentuates the relation between the surface dipoles and the work functions using concepts from classical physics combined with the state-of-the-art first-principles calculations

Interfacial engineering to modulate surface dipoles, work functions and dielectric confinement of halide perovskites

Authors are grateful to Maksym Kovalenko and Andriy Stelmakh for useful discussions and providing the MD snapshots.International audienceThe interfacial properties between perovskite photoactive and charge transport layers are critical for device performance and operational stability. Therefore, an accurate theoretical description of the link between surface dipoles and work functions is of scientific and practical interest. We show that for a CsPbBr 3 perovskite surface functionalized by dipolar ligand molecules, the interplay between surface dipoles, charge transfers, and local strain effects leads to upward or downward shifts of the valence level. We further demonstrate that the contribution of individual molecular entities to the surface dipoles and electric susceptibilities are essentially additive. Finally, we compare our results to those predicted from conventional classical approaches based on a capacitor model that links the induced vacuum level shift and the molecular dipole moment. Our findings identify recipes to fine-tune materials work functions that provide valuable insights into the interfacial engineering of this family of semiconductors