Double‐Side Si Photoelectrode Enabled by Chemical Passivation for Photoelectrochemical Hydrogen and Oxygen Evolution Reactions

Abstract

This paper describes a Si photoelectrode with an ultra-long minority carrier diffusion length (1940 µm) passivated by an amorphous Si layer, which provides a chemically passivated surface. With this extremely long carrier diffusion length, it is possible to separate the catalyst layer (metal) with the light absorption region on different sides of the Si photoelectrode, forming a double-side Si photoelectrode for photoelectrochemical water reduction and oxidation. The obtained photocathode exhibits a photocurrent of 39 mA cm −2 and applied bias photon-to-current efficiencies (ABPE) of 15.4% with stability up to 100 h. Meanwhile, 38.5 mA cm −2 photocurrent and ABPE of 5.8% with a 200 h stability are achieved when this structure is used as a photoanode. A monolithic unbiased artificial leaf is constructed, yielding an unbiased solar to hydrogen conversion efficiency of 3.7%. This chemically passivated Si photoelectrode breaks the trade-off between carrier transport and surface passivation in conventional Si photoelectrodes.

Unassisted Photoelectrochemical Cell with Multimediator Modulation for Solar Water Splitting Exceeding 4% Solar-to-Hydrogen Efficiency

“…An assisted PEC cell achieves a record STH efficiency of ∼5.8% for water oxidation with an applied bias of 1.0 V . However, the ultimate goal in developing high-performance photoelectrodes is to make efficient and unassisted PEC OWS devices .…”

“…Photoelectrochemical Overall Water Splitting. An assisted PEC cell achieves a record STH efficiency of ∼5.8% for water oxidation with an applied bias of 1.0 V. 56 However, the ultimate goal in developing high-performance photoelectrodes is to make efficient and unassisted PEC OWS devices. 57 Inspired by natural photosynthesis, we constructed an unassisted PEC device, composed of a BiVO 4 -based photoanode and a PIP-based photocathode with multimediator modulation for PEC OWS (Figure 5a), where the solar light passes through the front light-absorber (BiVO 4 ) before reaching the back light-absorber (PIP).…”

A Transparent, High‐Performance, and Stable Sb2S3 Photoanode Enabled by Heterojunction Engineering with Conjugated Polycarbazole Frameworks for Unbiased Photoelectrochemical Overall Water Splitting Devices

“…We, then, constructed a standalone unbiased PEC tandem cell by integrating the NiCoFe-B i /CPF-TCzB/Sb 2 S 3 photoanode with a back-illuminated Si (B-Si) photocathode (Figures S33 and S34, Supporting Information). [55,56] The detailed configuration of the device and corresponding experimental setup are shown in Figure 5a and Figure S35 (Supporting Information). The light can pass through the front NiCoFe-B i /CPF-TCzB/Sb 2 S 3 photoanode then reach the Si photocathode.…”

High‐Performance Si Photocathode Enabled by Spatial Decoupling Multifunctional Layers for Water Splitting

“…Our reported saturation photocurrents are at the intermediate range compared with the previous results. [ 3,24,32–36,38,41–44 ] For further comparison, the saturation photocurrent is 35.8 mA cm −2 based on the PEC performance of the Pt‐loaded AGLs/Si (Pt/AGLs/Si) photocathode, which is close to the values of Pt/PADs/Si photocathodes (Figure S15A, Supporting Information and Figure 3C). It is worth noting that the saturation photocurrent of Pt/AGLs/Si photocathode is lower than the short‐circuit current (38.1 mA cm −2 ) when it was tested as an as‐fabricated photovoltaic solar cell (Table S1, Supporting Information).…”