Challenges of modeling nanostructured materials for photocatalytic water splitting

Understanding the water splitting mechanism in photocatalysis is a rewarding goal as it will allow producing clean fuel for a sustainable life in the future. However, identifying the photocatalytic mechanisms by modeling photoactive nanoparticles requires sophisticated computational techniques based on multiscale modeling. In this review, we will survey the strengths and drawbacks of currently available theoretical methods at different length and accuracy scales. Understanding the surface-active site through Density Functional Theory (DFT) using new, more accurate exchange–correlation functionals plays a key role for surface engineering. Larger scale dynamics of the catalyst/electrolyte interface can be treated with Molecular Dynamics albeit there is a need for more generalizations of force fields. Monte Carlo and Continuum Modeling techniques are so far not the prominent path for modeling water splitting but interest is growing due to the lower computational cost and the feasibility to compare the modeling outcome directly to experimental data. The future challenges in modeling complex nano-photocatalysts involve combining different methods in a hierarchical way so that resources are spent wisely at each length scale, as well as accounting for excited states chemistry that is important for photocatalysis, a path that will bring devices closer to the theoretical limit of photocatalytic efficiency

Challenges of modeling nanostructured materials for photocatalytic water splitting

Understanding the water splitting mechanism in photocatalysis is a rewarding goal as it will allow producing clean fuel for a sustainable life in the future. However, identifying the photocatalytic mechanisms by modeling photoactive nanoparticles requires sophisticated computational techniques based on multiscale modeling. In this review, we will survey the strengths and drawbacks of currently available theoretical methods at different length and accuracy scales. Understanding the surface-active site through Density Functional Theory (DFT) using new, more accurate exchange–correlation functionals plays a key role for surface engineering. Larger scale dynamics of the catalyst/electrolyte interface can be treated with Molecular Dynamics albeit there is a need for more generalizations of force fields. Monte Carlo and Continuum Modeling techniques are so far not the prominent path for modeling water splitting but interest is growing due to the lower computational cost and the feasibility to compare the modeling outcome directly to experimental data. The future challenges in modeling complex nano-photocatalysts involve combining different methods in a hierarchical way so that resources are spent wisely at each length scale, as well as accounting for excited states chemistry that is important for photocatalysis, a path that will bring devices closer to the theoretical limit of photocatalytic efficiency

Influence of Electrolyte Cations on Ni(Fe)OOH Catalyzed Oxygen Evolution Reaction

Iron-doped, nickel oxyhydroxide (Ni­(Fe)­OOH) is one of the best catalysts for the oxygen evolution reaction (OER) under alkaline conditions. Due to Ni­(Fe)­OOH’s layered structure, electrolyte species are able to easily intercalate between the octahedrally coordinated sheets. Electrolyte cations have long been considered inert spectator ions during electrocatalysis, but electrolytes that penetrate into the catalyst may play a major role in the reaction process. In a joint theoretical and experimental study, we report the role of electrolyte counterions (K⁺, Na⁺, Mg²⁺, and Ca²⁺) on Ni­(Fe)­OOH catalytic activity in alkaline media. We show that electrolytes containing alkali metal cations (Na⁺ and K⁺) yield dramatically lower overpotentials than those with alkaline earth cations (Mg²⁺ and Ca²⁺). K⁺ and Na⁺ lower the overpotential because they have an optimal acidity and size that allows them to not bind too strongly or alter the stability of reaction intermediates. These two features required for intercalated cation species provide insight into selecting appropriate electrolytes for layered catalyst materials, and enable understanding the role(s) of electrolytes in the OER mechanism

CVD grown copper tungstate thin films for solar water splitting

In this paper, a direct chemical vapor deposition (CVD) approach is applied for the first time to synthesize high quality copper oxide (CuO), copper tungstate (CuWO4) and tungsten oxide (WO3) on F:SnO2 (FTO) substrates for photocatalytic water splitting.</p