Abstract:Novel thin film composite photocathodes based on device‐grade Cu(In,Ga)Se2 chalcopyrite thin film absorbers and transparent conductive oxide Pt‐implemented TiO2 layers on top are presented for an efficient and stable solar‐driven hydrogen evolution. Thin films of phase‐pure anatase TiO2 are implemented with varying Pt‐concentrations in order to optimize simultaneously i) conductivity of the films, ii) electrocatalytic activity, and iii) light‐guidance toward the chalcopyrite. Thereby, high incident‐photon‐to‐c… Show more
“…This field has primarily focused on optimizing the photovoltage and current needed to split water efficiently, and these efforts have borne fruit with multiple works showing greater than 10 % efficient devices ,. Recently, attention has turned towards stability with most publications reporting on devices which exhibit stability for at least 24 hours ,. On the other hand, long‐term durability tests (>1 month) have been much more limited.…”
Section: Figuresupporting
confidence: 83%
“…[4,5] Recently, attention has turned towards stability with most publications reporting on devices which exhibit stability for at least 24 hours. [6,7] On the other hand, long-term durability tests (> 1 month) have been much more limited. Maier et al demonstrated relatively low, but stable photocurrent under the HER conditions for 60 days in 1 M HCl using a Pt-coated crystalline silicon (c-Si), [8] while a recent study by the Jaramillo group used a thin MoS 2 protected c-Si to show durability for up to 62 days.…”
Section: Durability Testing Of Photoelectrochemical Hydrogen Productimentioning
This work investigates long‐term photoelectrochemical hydrogen evolution (82 days) in 1 M HClO4 using a TiO2:H protected crystalline Si‐based photocathode with metal‐oxide‐semiconductor (MOS) junctions. It is shown that day/night cycling leads to relatively rapid performance degradation while the photocurrent under the continuous light condition is relatively stable. We observed that the performance loss is mainly due to contamination of the catalytically active surface with carbonaceous material. By ultraviolet (UV) light exposure, we also observed that the activity can be restored, most likely due to photocatalytic degradation of organic compounds by the UV light excited TiO2 protection layer.
“…This field has primarily focused on optimizing the photovoltage and current needed to split water efficiently, and these efforts have borne fruit with multiple works showing greater than 10 % efficient devices ,. Recently, attention has turned towards stability with most publications reporting on devices which exhibit stability for at least 24 hours ,. On the other hand, long‐term durability tests (>1 month) have been much more limited.…”
Section: Figuresupporting
confidence: 83%
“…[4,5] Recently, attention has turned towards stability with most publications reporting on devices which exhibit stability for at least 24 hours. [6,7] On the other hand, long-term durability tests (> 1 month) have been much more limited. Maier et al demonstrated relatively low, but stable photocurrent under the HER conditions for 60 days in 1 M HCl using a Pt-coated crystalline silicon (c-Si), [8] while a recent study by the Jaramillo group used a thin MoS 2 protected c-Si to show durability for up to 62 days.…”
Section: Durability Testing Of Photoelectrochemical Hydrogen Productimentioning
This work investigates long‐term photoelectrochemical hydrogen evolution (82 days) in 1 M HClO4 using a TiO2:H protected crystalline Si‐based photocathode with metal‐oxide‐semiconductor (MOS) junctions. It is shown that day/night cycling leads to relatively rapid performance degradation while the photocurrent under the continuous light condition is relatively stable. We observed that the performance loss is mainly due to contamination of the catalytically active surface with carbonaceous material. By ultraviolet (UV) light exposure, we also observed that the activity can be restored, most likely due to photocatalytic degradation of organic compounds by the UV light excited TiO2 protection layer.
“…The CdS layer, which is ntype typically, plays a role as an electron transfer layer by forming pn-junction with the chalcopyrite layer, but not as a protection layer. Direct contact with a n-type TiO 2 protection layer typically struggles to provide an efficient charge separation as shown by Azarpira et al 72 On the other hand, Ros et al 70…”
Photoelectrochemical (PEC) solar-fuel conversion is a promising approach to provide clean and storable fuel (e.g., hydrogen and methanol) directly from sunlight, water and CO. However, major challenges still have to be overcome before commercialization can be achieved. One of the largest barriers to overcome is to achieve a stable PEC reaction in either strongly basic or acidic electrolytes without degradation of the semiconductor photoelectrodes. In this work, we discuss fundamental aspects of protection strategies for achieving stable solid/liquid interfaces. We then analyse the charge transfer mechanism through the protection layers for both photoanodes and photocathodes. In addition, we review protection layer approaches and their stabilities for a wide variety of experimental photoelectrodes for water reduction. Finally, we discuss key aspects which should be addressed in continued work on realizing stable and practical PEC solar water splitting systems.
“…RHE. To the best of our knowledge, this value is the highest efficiency among solution-processed CIGSSe films and comparable with vacuum-processed CIGSSe films 47–49 . Considering that relatively poor quality films are produced in the solution process, the PEC performance of these films is superior, indicating that the double-graded bandgap structure within the absorber film is very important in CIGSSe photocathode applications.Figure 9 I-V curves of Pt deposited PVA-CIGSSe and EC-CIGSSe photocathodes.…”
Surface modification of a Cu(In,Ga)(S,Se)2 (CIGSSe) absorber layer is commonly required to obtain high performance CIGSSe photocathodes. However, surface modifications can cause disadvantages such as optical loss, low stability, the use of toxic substances and an increase in complexity. In this work, we demonstrate that a double-graded bandgap structure (top-high, middle-low and bottom-high bandgaps) can achieve high performance in bare CIGSSe photocathodes without any surface modifications via a hetero-materials overlayer that have been fabricated in a cost-effective solution process. We used two kinds of CIGSSe film produced by different precursor solutions consisting of different solvents and binder materials, and both revealed a double-graded bandgap structure composed of an S-rich top layer, Ga- and S-poor middle layer and S- and Ga-rich bottom layer. The bare CIGSSe photocathode without surface modification exhibited a high photoelectrochemical activity of ~6 mA·cm−2 at 0 V vs. RHE and ~22 mA·cm−2 at −0.27 V vs. RHE, depending on the solution properties used in the CIGSSe film preparation. The incorporation of a Pt catalyst was found to further increase their PEC activity to ~26 mA·cm−2 at −0.16 V vs. RHE.
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