Unassisted Water Splitting Using Standard Silicon Solar Cells Stabilized with Copper and Bifunctional NiFe Electrocatalysts

Abstract

Silicon photovoltaic cells functionalized with water-splitting electrocatalysts are promising candidates for unassisted water splitting. In these devices, the total surface of silicon solar cells is covered with electrocatalysts, causing issues with (i) stabilizing silicon solar cells in water and (ii) device efficiency due to parasitic optical absorption in electrocatalysts. We describe and validate a water-splitting device concept using a crystalline silicon solar cell where the front side is covered with an insulating Si3N5 antireflection coating. The Ag contacts, fired through the antireflection coating, are removed and subsequently substituted with NiFe layered double hydroxide (LDH) or Cu/NiFe-LDH electrocatalysts. In this device, only the site of Ag contacts, nearly 2% of the total device area, is covered by the electrocatalyst. We found that this small area of the catalyst does not limit device performance and the addition of a Cu interlayer between Si and NiFe-LDH improves device performance and stability. The unassisted water-splitting efficiency of 11.31%, measured without separating the evolved gases, is achieved using a device composed of three series-connected silicon solar cells and an NiFe-LDH/Cu/Ni-foam counter electrode in a highly alkaline electrolyte.

Selective, Stable, Bias‐Free, and Efficient Solar Hydrogen Peroxide Production on Inorganic Layered Materials

“…Additionally, a crucial merit of this photoelectrode is that it is easier to control the photovoltage and photocurrent using a tandem or module structure, which provides a substantial advantage in constructing a suitable photoelectrode for the generation of specific target products. [ 32 ] Comparing LDH/Ni/eu@nfOP and a two‐series‐module‐type structural photoanode (denoted as 2m‐LDH/Ni/eu@nfOP, Figure S23, Supporting Information), the onset potential of 2m‐LDH/Ni/eu@nfOP is ‐0.28 V versus RHE, as shown in Figure 3d; this corresponds to a negative shift of 0.83 V compared to the onset potential of LDH/Ni/eu@nfOP. Further, the current density of 2m‐LDH/Ni/eu@nfOP is 7.59 mA cm –2 at 1.23 V versus RHE, which is approximately twice less than that of LDH/Ni/eu@nfOP.…”

Strategies for improving photoelectrochemical water splitting performance of Si‐based electrodes

“…Dabirian et al reported an Si photocathode functionalized with Cu/NiFe-LDH electrocatalysts. 117 Due to the high catalytic activity of NiFe-LDH, the photocathode achieved STH efficiency of 11.31% under no-bias condition and stability of about 33 h in 1.0 M NaOH electrolyte.…”

“… 137 The as‐prepared n‐Si/a‐TiO 2 /NiFe LDH photoanode without the buried junction showed a high photocurrent density of 36 mA cm −2 at 1.23 V vs. RHE, and operated more stably compared to n‐Si/NiFe LDH. Dabirian et al reported an Si photocathode functionalized with Cu/NiFe‐LDH electrocatalysts 117 . Due to the high catalytic activity of NiFe‐LDH, the photocathode achieved STH efficiency of 11.31% under no‐bias condition and stability of about 33 h in 1.0 M NaOH electrolyte.…”

Selenium‐Based Solar Cell with Conjugated Polymers as Both Electron and Hole Transport Layers to Realize High Water Tolerance as well as Good Long‐Term and Thermal Stability

“…For example, the traditional Si solar cells, which have been commercially used, still need to encapsulate the active layers with glass and poly(methyl methacrylate) (PMMA) to avoid contact with water. [ 8 ] The most popular absorber at present is CH 3 NH 3 PbI 3 , which would directly react with water molecules. [ 9 ] The as‐formed perovskite films would decompose under the ambient atmosphere, and the device fabrication processes must be conducted in the inert atmosphere.…”

“…To protect the functional layers and maintain the normal operation of solar cells, the encapsulation layer has to be meticulously designed according to varied real situations, which greatly impedes large-scale industrialization applications. [3][4][5][6][7][8] Therefore, developing encapsulation-free solar cells with great water tolerance is highly desirable. However, the progress in this field is quite frustrated due to two obstacles.…”