Decorating Cu2O with Ni-doped metal organic frameworks as efficient photocathodes for solar water splitting

Severe photocorrosion and fast photoexcited charges recombination hinder the application of Cu 2 O in photoelectrochemical (PEC) water splitting. In this work, Ni-doped metal-organic frameworks is firstly applied to improve the performance of electrodeposited Cu 2 O. A decorative layer of Ni-doped Cu 3 (BTC) 2 (Ni-CuBTC) was in-suit constructed on Cu 2 O through solvothermal followed by ion-exchange. Cu 2 O/Ni-CuBTC photocathodes increase absorption edge to ∼800 nm, positive shift flat band position to 0.4 V, and decrease Tafel value to 74 mV/dec. These results confirm the decorative layer can extend light absorption, facilitate photoexcited charge separation and transfer, and enhance HER activity. A photocurrent density of −1.51 mA/cm 2 at 0 V RHE is obtained with the decoration of Ni-CuBTC, which is 3.4 times of pristine Cu 2 O photocathode. Here, the PEC water splitting performance of electrodeposited Cu 2 O has been significantly improved with noble-metal-free decorations, which provides a new idea for solving the defects of Cu 2 O based photocathode.