High‐Performance Si Photocathode Enabled by Spatial Decoupling Multifunctional Layers for Water Splitting
Zongwei Mei, Yongji Chen, Shengfu Tong, Yang Li, Jian Liu, Lizhi Sun, Wu Zhong, Xinyan Dong, Yuchen Ji, Yuan Lin, Haibiao Chen, Feng Pan
Abstract
Abstract Spatial decoupling of light absorption and catalytic reaction is a promising approach to improve the efficiency and stability of Si photoelectrodes. Herein, patterned Ag dots (PADs) are fabricated as the front electrode on a glass layer on commercial SiN x ‐coated monocrystalline p‐n + Si by an industrial manufacture strategy. It is found that the electron tunneling glass layer offers excellent protection to Si photocathode in an acidic electrolyte (0.5 M H 2 SO 4 ). The SiN x layer for antireflection and surface passivation also resists the corrosive electrolyte. Under 1 sun (AM 1.5G) illumination, PADs‐decorated photocathode with a 0.75 mm dot‐spacing exhibits a saturation photocurrent of 36.1 mA cm −2 and a photovoltage of 0.61 V when Pt is electrodeposited as the hydrogen evolution catalyst on PADs. The applied bias photo‐to‐current conversion efficiency (ABPE) reaches 9.7%. This performance is enabled by the simultaneous optimization of light absorption and collection of photoexcited electrons. The photocurrent can remain stable for about 100 h at 0 V versus the reversible hydrogen electrode (RHE). This study identifies a new combination of multifunctional spatial‐decoupling layers that is efficient in both light absorption, transfer of photoexcited electrons, and stable in an acidic electrolyte.