Controllable fabrication of nanostructured materials for photoelectrochemical water splitting via atomic layer deposition

Abstract

Photoelectrochemical (PEC) water splitting is an attractive approach to generate hydrogen as a clean chemical fuel from solar energy. But there remain many fundamental issues to be solved, including inadequate photon absorption, short carrier diffusion length, surface recombination, vulnerability to photo-corrosion, and unfavorable reaction kinetics. Owing to its self-limiting surface reaction mechanism, atomic layer deposition (ALD) is capable of depositing thin films in a highly controllable manner, which makes it an enabling technique to overcome some of the key challenges confronted by PEC water splitting. This tutorial review describes some unique and representative applications of ALD in fabricating high performance PEC electrodes with various nanostructures, including (i) coating conformal thin films on three-dimensional scaffolds to facilitate the separation and migration of photocarriers and enhance light trapping, as well as realizing controllable doping for bandgap engineering and forming homojunctions for carrier separation; (ii) achieving surface modification through deposition of anti-corrosion layers, surface state passivation layers, and surface catalytic layers; and (iii) identifying the main rate limiting steps with model electrodes with highly defined thickness, composition, and interfacial structure.

Strongly Coupled Nafion Molecules and Ordered Porous CdS Networks for Enhanced Visible‐Light Photoelectrochemical Hydrogen Evolution

“…[ 26 ] Coating a passivation layer onto the surface of 3D nanostructured photoelectrode is a practical means to reduce the surface trap density which promotes photogenerated charge recombination at the semiconductor/electrolyte interface. [27][28][29] A number of techniques, such as atomic layer deposition (ALD), [ 30 ] spin coating, [ 31 ] electrochemical deposition, [ 3,32 ] sputtering, [ 7 ] and electron beam evaporation [ 7 ] have been developed to coat the passivation layer onto the surface of photoelectrodes. However, in most cases, it is diffi cult to achieve a continuous and conformal passivation layer on 3D surfaces of photoelectrodes, [ 29 ] even by ALD.…”

A review on plasmonic metal⿿TiO2 composite for generation, trapping, storing and dynamic vectorial transfer of photogenerated electrons across the Schottky junction in a photocatalytic system

“…In addition the accumulation of electrons on Ag deposits shifts the position of its Fermi level closer to TiO 2 CB. The excited electrons from TiO 2 CB (transferred from Ag deposits), were collected by indium tin oxide (ITO) acting as current collector thus improving the photocurrent and photovoltaic performance under the visible light region [167]. Ag/N-TiO 2 nanotube arrays fabricated via electrodeposition method at deposition potential of −1.0 V with deposition time of 5 s showed enhanced photodegradation of acid orange II compared to TiO 2 and N-TiO 2 [168].…”

Enhanced photoelectrochemical water-splitting performance of semiconductors by surface passivation layers

“…(c) Passivation layers can be fabricated by atomic layer deposition (ALD), 46 (d) Passivation layers can readily be incorporated onto high surface area or high aspect ratio nanostructures.…”