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

Here, cobalt-doped copper bismuth oxide (Co-CuBiO) was synthesized via a facile hydrothermal method for photoelectrocatalytic (PEC) hydrogen production. The results disclosed that the 5% Co-doped CuBiO has better PEC activity which is ∼3 fold higher than pristine CuBiO. The doping of cobalt in CuBiO 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 CuBiO photocathode further modified with TiO-P25 to form a Co-CuBiO/TiO p-n heterojunction. This Co-CuBiO/TiO photocathode displayed a photocurrent density of 330 μA cm at +0.5 V vs. RHE which was ∼2 fold higher than Co-CuBiO. 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.