Amorphous TiO₂ coatings stabilize Si, GaAs, and GaP photoanodes for efficient water oxidation.
نویسندگان
چکیده
Although semiconductors such as silicon (Si), gallium arsenide (GaAs), and gallium phosphide (GaP) have band gaps that make them efficient photoanodes for solar fuel production, these materials are unstable in aqueous media. We show that TiO2 coatings (4 to 143 nanometers thick) grown by atomic layer deposition prevent corrosion, have electronic defects that promote hole conduction, and are sufficiently transparent to reach the light-limited performance of protected semiconductors. In conjunction with a thin layer or islands of Ni oxide electrocatalysts, Si photoanodes exhibited continuous oxidation of 1.0 molar aqueous KOH to O2 for more than 100 hours at photocurrent densities of >30 milliamperes per square centimeter and ~100% Faradaic efficiency. TiO2-coated GaAs and GaP photoelectrodes exhibited photovoltages of 0.81 and 0.59 V and light-limiting photocurrent densities of 14.3 and 3.4 milliamperes per square centimeter, respectively, for water oxidation.
منابع مشابه
The influence of structure and processing on the behavior of TiO2 protective layers for stabilization of n-Si/TiO2/Ni photoanodes for water oxidation.
Light absorbers with moderate band gaps (1-2 eV) are required for high-efficiency solar fuels devices, but most semiconducting photoanodes undergo photocorrosion or passivation in aqueous solution. Amorphous TiO2 deposited by atomic-layer deposition (ALD) onto various n-type semiconductors (Si, GaAs, GaP, and CdTe) and coated with thin films or islands of Ni produces efficient, stable photoanod...
متن کاملMicroscopic Study of Atomic Layer Deposition of TiO2 on GaAs and Its Photocatalytic Application
We report a microscopic study of p-GaAs/TiO2 heterojunctions using cross-sectional high resolution transmission electron microscopy (HRTEM). The photocatalytic performance for both H2 evolution and CO2 reduction of these heterostructures shows a very strong dependence on the thickness of the TiO2 over the range of 0−15 nm. Thinner films (1−10 nm) are amorphous and show enhanced catalytic perfor...
متن کاملStable solar-driven oxidation of water by semiconducting photoanodes protected by transparent catalytic nickel oxide films.
Reactively sputtered nickel oxide (NiOx) films provide transparent, antireflective, electrically conductive, chemically stable coatings that also are highly active electrocatalysts for the oxidation of water to O2(g). These NiOx coatings provide protective layers on a variety of technologically important semiconducting photoanodes, including textured crystalline Si passivated by amorphous silic...
متن کاملWater splitting with silver chloride photoanodes and amorphous silicon solar cells.
A thin silver chloride layer deposited on a conducting support photocatalyzes the oxidation of water to O(2) in the presence of a small excess of silver ions in solution. The light sensitivity in the visible part of the spectrum is due to self-sensitization caused by reduced silver species. Anodic polarization reoxidizes the reduced silver species. To test its water splitting capability, AgCl p...
متن کاملCorrelation of Ti 3 + states with photocatalytic enhancement in TiO 2 - passivated p - GaAs
Recently, we reported enhanced H 2 evolution on TiO 2-passivated GaAs. Based on density functional theory (DFT) calculations, this enhancement was attributed to Ti 3+ states, which bind reactant species and increase charge transfer across the semiconductor–liquid interface. Here, we provide a quantitative correlation between Ti 3+ density, as measured by X-ray photoemission spectroscopy (XPS) a...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
- Science
دوره 344 6187 شماره
صفحات -
تاریخ انتشار 2014