Uplifting the charge carrier separation and migration in Co-doped CuBi2O4/TiO2 p-n heterojunction photocathode for enhanced photoelectrocatalytic water splitting

Abstract

Here, cobalt-doped copper bismuth oxide (Co-CuBi₂O₄) was synthesized via a facile hydrothermal method for photoelectrocatalytic (PEC) hydrogen production. The results disclosed that the 5% Co-doped CuBi₂O₄ has better PEC activity which is ∼3 fold higher than pristine CuBi₂O₄. The doping of cobalt in CuBi₂O₄ improves the interfacial charge transfer at an electrode/electrolyte interface and reduces the recombination rate of photogenerated electron-hole pairs. This higher performed 5% Co-doped CuBi₂O₄ photocathode further modified with TiO₂-P25 to form a Co-CuBi₂O₄/TiO₂ p-n heterojunction. This Co-CuBi₂O₄/TiO₂ photocathode displayed a photocurrent density of 330 μA cm^-2 at +0.5 V vs. RHE which was ∼2 fold higher than Co-CuBi₂O₄. Because this p-n junction affords inner electric field in the space charge region that helps for further minimization of electron-hole recombination, which facilitate efficient charge separation and transport thereby enhance the PEC water reduction.

Keywords: CuBi(2)O(4)/TiO(2); Hydrogen production; Photoelectrocatalysis; Water splitting; p‐n heterojunction.