Utilizing a Siloxane-Modified Organic Semiconductor for Photoelectrochemical Water Splitting

Abstract

Weexplore the potential of employing diketopyrrolopyrrole (DPP)based pi-conjugated OSs as a hole transport layer material inheteroatom-doped hematite (Ti-Fe2O3/Ge-Fe2O3) photoanodes for efficient photoelectrochemicalwater splitting. The siloxane-modified pi-conjugated polymer(P-Si) with a high carrier mobility and crystallinity revealedgreat potential to extract holes by forming a built-in potential withhematite photoanodes while showing high stability in an alkaline electrolytefor photoelectrochemical water oxidation. Because of the easy holeextraction and subsequent fast hole transport property of the P-Si interlayer between NiFe-(OH)( x ) and Ge-doped porous Fe2O3(Ge-PH), NiFe-(OH)( x )/P-Si/Ge-PH showed a 1.8-fold increasein photocurrent density (4.57 mA cm(-2) at 1.23 V-RHE) with a cathodic shift of the onset potential (0.735 V-RHE) and good stability for 65 h compared to Ge-PH. This studydemonstrates the successful use of inherently unstable pi-conjugatedOSs as a hole extracting/transport medium in a photoanode, addressingthe intrinsic recombination issues of hematite for efficient and stablewater splitting.