Tuning built-in potential of NiP/NiFe LDH p-n junction towards efficient electrocatalytic water and urea oxidation

Oxygen evolution reaction (OER) and urea oxidation reaction (UOR) are critical half-reactions to realize sustainable hydrogen production. However, the sluggish dynamics derived from the multi-electron pathways necessitate the exploration for efficient catalysts. Herein, a p-n junction nanorod array composed of Mo doped NiP nanorod and ultrathin NiFe LDH nanosheets (NiMoP/NiFe LDH) is proposed to regulate charge distribution of interface for triggering decomposition of water and urea. The p-n junction with a powerful built-in potential (E_BI) of 1.2 V at the interface facilitates the adsorption and fracture of chemical group in water and urea molecules. Consequently, the heterostructured electrode demonstrates exceptional electrochemical performance with ultralow potentials of 1.43 and 1.33 V (vs. RHE) at 10 mA cm⁻² for OER and UOR, respectively. The overall urea electrolysis driven by NiMoP/NiFe LDH needs only 1.51 V to deliver 100 mA cm⁻². This work demonstrates a promising strategy to regulate the E_BI of semiconductor heterostructure for energy conversion and sewage treatment.