Constructing abundant phase interfaces of the sulfides/metal-organic frameworks p-p heterojunction array for efficient overall water splitting and urea electrolysis

Designing efficient electrocatalysts to improve the overall water splitting and urea electrolysis efficiency for hydrogen generation can greatly solve the dilemma of energy shortage and environmental pollution. In this work, Co8FeS8@CoFe-MOF/NF heterojunction arrays were fabricated by embedding sulfides into the surface of metal-organic frameworks (MOFs) nanosheets as multifunctional electrocatalyst. The introduction of sulfide on CoFe-MOF/NF can not only adjust the electronic structure (electron-rich state) and change the surface properties (more hydrophilic), but also increase the active area to enhance the catalytic activity. The in situ Raman shows Co8FeS8@CoFe-MOF/NF is more easily to generate active species at low potentials and generates a higher content of active β-MOOH phase than CoFe-MOF/NF. Therefore, the Co8FeS8@CoFe-MOF/NF exhibits excellent oxygen evolution reaction (OER) performance with an overpotential of 213 mV at 10 mA cm-2. Furthermore, when used as a urea oxidation reaction (UOR), only an ultralow potential of 1.311 V at 10 mA cm-2. More importantly, the assembled two-electrode drives overall water splitting and urea electrolysis with cell voltages of 1.62 V and 1.55 V at 10 mA cm-2, respectively. This work provides insights into the preparation of electrocatalysts with multifunctional heterostructure arrays for hydrogen production.