Spatial control of cocatalysts and elimination of interfacial defects towards efficient and robust CIGS photocathodes for solar water splitting
- 31 July 2018
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Energy & Environmental Science
- Vol. 11 (8), 2025-2034
- https://doi.org/10.1039/c7ee03650g
Abstract
Chalcopyrite thin film absorbers such as Cu(In,Ga)Se-2 (CIGS) exhibit excellent solar energy conversion efficiency, particularly when coupled with CdS to form an excellent p-n junction. To advance CIGS towards an efficient photoelectrochemical (PEC) hydrogen evolution reaction (HER), a protective overlayer (typically TiO2) is needed to prevent the corrosion of CIGS and CdS in the electrolyte, and a HER catalyst (typically Pt) is required to promote the surface reaction. However, it is a great challenge to realize delicate spatial control of the HER catalyst on the surface of the protective overlayer using the traditional deposition method. The charge transport through the CdS/overlayer interface is also of vital importance but is rarely considered. Herein, through a new two-step platinization strategy, the dispersion and particle size of Pt nanoparticles are independently controlled to realize high HER catalytic activity. Moreover, defects at the CdS/TiO2 interface are passivated via an ultrathin Al2O3 insertion layer. Consequently, we have obtained a robust CIGS/CdS/Al2O3/TiO2/Pt photocathode for PEC hydrogen evolution, which yields an applied bias photon-to-current efficiency (ABPE) of 6.6% in neutral electrolyte with a long-term stability up to 8 h (4.5% drop), and an unprecedented ABPE of 9.3% in acidic electrolyte that is the highest among chalcopyrite-based photocathodes. When paired with a BiVO4 photoanode to form a PEC tandem cell, an unbiased solar-to-hydrogen conversion efficiency of 1.01% is achieved.Keywords
Funding Information
- National Natural Science Foundation of China (21525626, 21722608, U1463205, U1662111)
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