A Review of Recent Developments in Molecular Dynamics Simulations of the Photoelectrochemical Water Splitting Process

Abstract

In this review, we provide a short overview of the Molecular Dynamics (MD) method and how it can be used to model the water splitting process in photoelectrochemical hydrogen production. We cover classical non-reactive and reactive MD techniques as well as multiscale extensions combining classical MD with quantum chemical and continuum methods. Selected examples of MD investigations of various aqueous semiconductor interfaces with a special focus on TiO2 are discussed. Finally, we identify gaps in the current state-of-the-art where further developments will be needed for better utilization of MD techniques in the field of water splitting.

Vibrational spectroscopy by means of first‐principles molecular dynamics simulations

“…For the latter two, the leap‐frog or velocity Verlet algorithm 17 is used in standard calculations. In this case, at each (half) time step, either the positions or the forces and velocities are updated according to the chosen level of theory 18 …”

“…In this case, at each (half) time step, either the positions or the forces and velocities are updated according to the chosen level of theory. 18 For simulations of large systems and time scales, it is advantageous to use force fields fitted to experiments or data acquired from first principles. In this case, the forces are determined by considering bond lengths, bond angles and dihedral angles among other classifiers.…”

Atomic-scale modeling of the dissolution of oxidized platinum nanoparticles in an explicit water environment

“…Over the past decade several computational techniques have been used to describe the mechanisms that control ORR. 4,5,14,15 For instance, density functional theory (DFT) and quantum statistics have been used to describe electrochemical reactions at steady state. With DFT, Pt-O surface interactions have been extensively studied to determine how different Pt surfaces respond to electrochemical environments.…”

Nonequilibrium Ab Initio Molecular Dynamics Simulation of Water Splitting at Fe2O3–Hematite/Water Interfaces in an External Electric Field

“…To a large extent, molecular dynamics (MD) techniques have been very useful in investigating, characterizing, and classifying the structural, dynamical, and vibrational behavior of bulk and adsorbed water molecules at a variety of metal oxide surfaces; for instance, titania–water renders itself an attractive photoanode material for solar water splitting. Moreover, molecular dynamics have been explored in an effort to further understand and improve the photoelectrochemical water-dissociation process. − In particular, the titania–water interface has enabled the exploration of hydrogen-bond kinetics, spatial distribution functions, ion adsorption, electric double-layer surfaces, − the emergence of vibrational modes, and water–dipole orientations. Calculations based on density functional theory (DFT) of titania–water interfaces, specifically ab initio MD (AIMD), have reportedly been used to simulate a variety of surfaces ranging from partial to full coverage and multiple water layers. , AIMD has also contributed to providing key insights into librational motions of higher-frequency modes of the titania–adsorbed water interface.…”

“…In addition, the transport of ionic species within the bulk-water phase also explored by the MD technique has served to enhance the processes or properties necessary for optimizing the performance and efficiency of PEC systems. 15 An intriguing and yet sparsely explored area is the application of an externally applied electric field at the hematite−water interface to boost the performance and efficiency of photolysis. Aside from electrolysis, the production of H 2 from water vis-a-vis electric fields has received significant attention in instances such as ionization 26 and plasma methods.…”