In-situ introduction of CePO4 for stabilizing electrocatalytic activity of quasi-MOF with partially missing C≡N skeleton

Hydrogen (H2) is considered one of the most promising green energy sources due to its high combustion heat value and non-polluting byproducts after combusting. Electrolysis of water to product H2 is a safe and stable way. Nevertheless, the current commercially available electrocatalysts suffer from high cost and slow reaction kinetics, hindering the widespread application of electrocatalytic water splitting. Metal-organic framework (MOF) have been concerned widespread as materials with high activity sites in the field of electrocatalyst. However, the presence of organic frameworks in MOF results in slow electron transfer rates and weak catalytic activity. To address this issue, this research has constructed a novel CePO4/quasi-MOF heterostructure with partial amorphous phase. The partial absence of organic frameworks in this heterostructure exposes more active metal sites, while the presence of the amorphous phase enhances the porosity of material. The overpotentials (η10) of CePO4/Ce-PBA-2 for the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) are 242 and 192 mV, respectively. The density functional theory (DFT) calculations demonstrate that constructing the CePO4/Ce-PBA-2 heterostructure with missing C≡N frameworks partially accelerates the electron transfer between metal ions, improving the reaction kinetics of HER and OER effectively. On the other hand, CePO4/Ce-PBA-2 exhibited a specific capacitance of 1346.7F g−1 at 1 A/g. The CePO4/quasi-MOF heterostructure achieves efficient electrocatalytic water splitting and energy storage in supercapacitors simultaneously. This study further paves the way for the application and development of MOF in the field of electrochemistry.