Crystal Facet Engineering of Photoelectrodes for Photoelectrochemical Water Splitting

Abstract

Photoelectrochemical (PEC) water splitting is a promising approach for solar-driven hydrogen production with zero emissions, and it has been intensively studied over the past decades. However, the solar-to-hydrogen (STH) efficiencies of the current PEC systems are still far from the 10% target needed for practical application. The development of efficient photoelectrodes in PEC systems holds the key to achieving high STH efficiencies. In recent years, crystal facet engineering has emerged as an important strategy in designing efficient photoelectrodes for PEC water splitting, which has yet to be comprehensively reviewed and is the main focus of this article. After the Introduction, the second section of this review concisely introduces the mechanisms of crystal facet engineering. The subsequent section provides a snapshot of the unique facet-dependent properties of some semiconductor crystals including surface electronic structures, redox reaction sites, surface built-in electric fields, molecular adsorption, photoreaction activity, photocorrosion resistance, and electrical conductivity. Then, the methods for fabricating photoelectrodes with faceted semiconductor crystals are reviewed, with a focus on the preparation processes. In addition, the notable advantages of the crystal facet engineering of photoelectrodes in terms of light harvesting, charge separation and transfer, and surface reactions are critically discussed. This is followed by a systematic overview of the modification strategies of faceted photoelectrodes to further enhance the PEC performance. The last section summarizes the major challenges and some invigorating perspectives for future research on crystal facet engineered photoelectrodes, which are believed to play a vital role in promoting the development of this important research field.

Efficient BiVO4 Photoanodes by Postsynthetic Treatment: Remarkable Improvements in Photoelectrochemical Performance from Facile Borate Modification

“…100 nm), and slow water oxidation kinetics. [7] Plenty of approaches have been attempted to overcome these limitations,i ncluding element doping, [8] morphology engineering, [9] heterostructure formation, [10] oxygen evolution catalysts (OECs)-layer loading, [11] crystal facet engineering, [12] plasmonic enhancement, [13] and combinations thereof.However, the efficiency of BiVO 4 photoanodes is still far from an application level. [5a] Beside these well-studied techniques,aseries of postsynthetic treatments,aconcept proposed by Smith and Stefik, have recently emerged as as imple and effective strategy to enhance the intrinsic photocatalytic activity of BiVO 4 photoanodes.…”

A Hybrid Artificial Photocatalysis System Splits Atmospheric Water for Simultaneous Dehumidification and Power Generation

“…Systems based on ferroelectric–semiconductor, typically requiring an external energy for polarization pretreatment, also suffers from a limitation of degeneration with the polarized built‐in electric field over time . “Crystal plane engineering” is an efficient method for exposing different crystal planes in a nanoparticle, which aids in achieving difference surface potentials at various planes ascribed to the varied atomic arrangements . Using this strategy, a polarizing electric field can be induced between crystal planes.…”

“…[11][12][13] "Crystal plane engineering" is an efficient method for exposing different crystal planes in a nanoparticle, which aids in achieving difference surface potentials at various planes ascribed to the varied atomic arrangements. [6,[14][15][16] Using this strategy, a polarizing electric field can be induced between crystal planes. Hence, by exploiting crystal planes' electric filed to orient ferroelectric dipole in a nanoparticle, it is possible to drive photocatalyst water splitting without extra energy for polarization and enhance the photogenerated charge's mobility.…”

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“…Collection of hydrogen in the form of a hydride opens, more generally, the prospect of subsequently using such materials as anodes in batteries employing oxygen reduction cathodes.Photocatalytic water splitting is widely investigated as a promising means for sustainable fuel generation using sunlight. [1][2][3][4][5] When the splitting process is conducted via suspensions of Adv. Energy…”