Alqahtani, M;
Sathasivam, S;
Cui, F;
Steier, L;
Xia, X;
Blackman, C;
Kim, E;
... Wu, J; + view all
(2019)
Heteroepitaxy of GaP on silicon for efficient and cost-effective photoelectrochemical water splitting.
Journal of Materials Chemistry A
, 7
(14)
pp. 8550-8558.
10.1039/c9ta01328h.
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Abstract
Photoelectrochemical production of hydrogen by using sunlight to split water offers a sustainable approach for clean energy generation. III-V Semiconductors have shown the highest efficiencies for photoelectrochemical water splitting but the prohibitive cost of commercial single-crystalline GaP wafers limit practical use and large-scale application. Here, we report a high-quality GaP photocathode directly grown on a silicon substrate by solidsource molecular beam epitaxy. The photocathode can be stabilized under acidic electrolyte 1M HClO4 (pH 0) by a combined an amorphous TiO2 layer coated with a molybdenum sulphide MoS2 hydrogen evolution catalyst by atomic layer deposition (ALD). Under simulated AM 1.5G solar illumination, the Si/GaP photocathode yielded a maximum photocurrent density of 0.95 (mA/ cm2 ) with a proton reduction onset potential was 467 mV versus the reversible hydrogen electrode. The average Faradaic efficiency of the Si/GaP photocathode was measured to be over 73.4±20.2% for over 100 minutes. The photoelectrochemical studies for the Si/GaP photocathode show the potential for widespread deployment of cost-effective photoelectrodes for hydrogen generation.
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