Cu:NiO as a hole-selective back contact to improve the photoelectrochemical performance of CuBi₂O₄ thin film photocathodes

Abstract

Cu doped NiO (Cu:NiO) back contact layers are inserted between FTO substrates and CuBi2O4 thin films to improve the performance of CuBi2O4 photocathodes.

Pure CuBi2O4 Photoelectrodes with Increased Stability by Rapid Thermal Processing of Bi2O3/CuO Grown by Pulsed Laser Deposition

“…Figure a compares the transmittance and reflectance of a PLD/RTP‐grown CuBi 2 O 4 film with a CuBi 2 O 4 film fabricated by spray‐pyrolysis. [ 9 ] Both films are deposited on FTO glass and have a similar thickness of ≈250 nm. The transmittance of the CuBi 2 O 4 produced by combined PLD and RTP differs by two features.…”

“…Despite its favorable characteristics, the development of CuBi 2 O 4 photocathodes suffers from two critical drawbacks: i) photocurrents densities are still well below the theoretical limit due to poor charge separation and transport in the bulk of the films, [ 9 ] and ii) poor photo‐electrochemical stability in aqueous solutions, a common challenge in photocathodes containing Cu. [ 10 ] Efforts to overcome these drawbacks include modifying the FTO/CuBi 2 O 4 interface, [ 9,11,12 ] creating a gradient self‐doping in the CuBi 2 O 4 layer to improve the charge separation efficiency, and using thin protection layers. [ 5,13,14 ] To further improve the study and development of CuBi 2 O 4 photocathodes and to improve their photocurrent densities and stability, [ 15 ] it is necessary to fabricate them with high quality and purity, minimizing impurities and defects.…”

“…Deposition techniques such as spray‐pyrolysis, spin coating, drop‐casting, inkjet printing, and electrochemical deposition are widely used to fabricate CMO photoelectrodes, and CuBi 2 O 4 in particular. [ 1,3,5,9,11,28–30 ] These chemical techniques rely on the use of a solvent, molecular precursors, and stabilizers, which are known to affect the formation mechanism, the films' morphology, and therefore its electronic properties. However, these films typically consist of particles with ill‐defined shapes, different roughness (porosity), and crystallinity, as well as fluctuations in stoichiometry.…”

“…The phase‐pure CuBi 2 O 4 films comprised of micron‐sized particles, and their optical, electronic, and photo‐electrochemical properties were investigated and compared to porous CuBi 2 O 4 photoelectrodes made by the spray‐pyrolysis technique, which is currently the benchmark technique to fabricate CuBi 2 O 4 photoelectrodes. [ 5,9,28 ] The phase‐pure CuBi 2 O 4 photoelectrodes made by combined PLD and RTP demonstrate superior electronic properties and unprecedented photo‐electrochemical stability without protection layers and catalysts.…”

Benchmark performance of low-cost Sb2Se3 photocathodes for unassisted solar overall water splitting

“…the formation of undesirable detrimental phases during processing, could pose a major obstacle to large-scale commercialisation. In recent years, various low-cost semiconductors have emerged, such as Cu 2 S (E g~1 .5 eV) 13 , CuFeO 2 (E g~1 .5 eV) 14 , CuBi 2 O 4 (E g~1 .7 eV) 15 , CuSbS 2 (E g~1 .5 eV) 16 , and SnS (E g~1 .3 eV) 17 . However, none of them have satisfied all the requirements for an ideal semiconductor for PEC water splitting.…”