Computational Approaches to Photoelectrode Design through Molecular Functionalization for Enhanced Photoelectrochemical Water Splitting

Abstract

Photoelectrochemical water splitting is a promising carbon‐free approach to produce hydrogen from water. A photoelectrochemical cell consists of a semiconductor photoelectrode in contact with an aqueous electrolyte. Its performance is sensitive to properties of the photoelectrode/electrolyte interface, which may be tuned through functionalization of the photoelectrode surface with organic molecules. This can lead to improvements in the photoelectrode's properties. This Minireview summarizes key computational investigations on using molecular functionalization to modify photoelectrode stability, barrier height, and catalytic activity. It is discussed how first‐principles density functional theory, first‐principles molecular dynamics, and device modeling simulations can provide predictive insights and complement experimental investigations of functionalized photoelectrodes. Challenges and future directions in the computational modeling of functionalized photoelectrode/electrolyte interfaces within the context of experimental studies are also highlighted.

Artificial photosynthesis for high‐value‐added chemicals: Old material, new opportunity

“…Recent studies on electrocatalytic or PC reactions are focused on not only achieving high efficiency but also understanding the mechanism of target reaction because the reaction mechanism determines the results of catalytic reaction. In fact, the mechanistic study based on computational calculation requires various information, such as surface/interface structure, oxidation states or adsorption properties of catalyst materials 125–127 . Thus, for a better understanding of catalyst materials, highly developed investigation, such as X‐ray absorption fine structure, X‐ray absorption near edge structure, and electron microscopies are introduced to the materials characterization, and the results are applied to the computational calculations 128,129 .…”

“…In fact, the mechanistic study based on computational calculation requires various information, such as surface/interface structure, oxidation states or adsorption properties of catalyst materials. [125][126][127] Thus, for a better understanding of catalyst materials, highly developed investigation, such as X-ray absorption fine structure, X-ray absorption near edge structure, and electron microscopies are introduced to the materials characterization, and the results are applied to the computational calculations. 128,129 Moreover, in situ or in operando investigations on catalytic reactions are frequently reported nowadays, where these techniques provide very important information during each reaction steps in the mechanism.…”

Hybrid Photoelectrochemical Water Splitting Systems: From Interface Design to System Assembly

“…Despite these, other methods are still widely used due to their relatively facial operation conditions and unique functions, such as CV in redox potential analysis, XPS in surface atom ratio determination, and MS and NMR in molecule structure identification. In addition to experimental techniques, DFT calculations, have also been widely used as an important tool in the demonstration of catalytic mechanism 111. Fujita and co‐workers employed a combined solution‐surface‐DFT calculational approach to study the mechanism of water oxidation by [Ru(bda)(L) 2 ] ( 1 in Figure 2 , bda is 2,2′‐bipyridine‐6,6′‐dicarboxylic acid and L is 4‐picoline or isoquinoline) with the X‐ray structure of intermediates and reactivities identified 107.…”

“…In addition to experimental techniques, DFT calculations, have also been widely used as an important tool in the demonstration of catalytic mechanism. [111] Fujita and co-workers employed a combined solution-surface-DFT calculational approach to study the mechanism of water oxidation by [Ru(bda)(L) 2 ] (1 in Figure 2, bda is 2,2′-bipyridine-6,6′-dicarboxylic acid and L is 4-picoline or isoquinoline) with the X-ray structure of intermediates and reactivities identified. [107] Sakai and co-workers introduced a similar time-dependent DFT calculational approach to identify Ru V = O as an intermediate in the oxidation of water by [Ru(terpy)(bpy) (OH 2 )] 2+ (2 in Figure 2, terpy is 2,2′,2′-terpyridine and bpy is 2,2′-bipyridine) and rapid pathways that occurred after the rate limited step.…”

Understanding Surface Modulation to Improve the Photo/Electrocatalysts for Water Oxidation/Reduction

“…The intrinsic dipole of the molecules and the electronic interaction between molecules and the substrate can influence the polarization at the interface to change the band bending on the surface. [12,30,59,60]. Surface functionalities tune the magnitude and direction of the surface dipole.…”