CuO/CuBi2O4 heterojunction photocathode: High stability and current densities for solar water splitting

Global energy crisis escalates the emphasis on ways to find green and sustainable solutions. Photoelectrochemical (PEC) conversion is one of the key technologies to fulfill the energy demand by converting solar energy into chemical fuels. Binary copper oxides suffer from severe photocorrosion and ternary copper oxides such as copper bismuth oxide (CuBi2O4) exhibit poor charge separation and transfer. In this work, a composite consisting of CuO annealed at 450 °C and CBO electrodeposited for 5 min on top of it (CuO-450/CBO-5) showed the best performance with a positive shift of 0.2 V in onset potential, a high current density of −0.9 mA cm−2 at 0.1 V vs RHE and high stability over pure CuO. The systematic deposition of CBO on CuO leads to intimate contact between the two semiconductors wherein, CuO acts as a hole carrier and CBO accommodates the hydrogen evolution reaction (HER).