Vacancy engineering and hydrophilic construction of CoFe-MOF for boosting water splitting by in situ phytic acid treatment

Deliberate engineering of the structures and components of Metal–organic frameworks (MOFs) can provide unlimited potential for developing efficient electrocatalysts for water splitting. Herein, we develop a green strategy to synthesize CoFe–MOF@Pa via a simple and controllable phytic acid (Pa) etching technique. The Pa etching strategy can break the M−O in CoFe–MOF to create vacancies and introduce hydrophilic groups on the surface of CoFe–MOF to enhance the hydrophilicity. The obtained porous CoFe–MOF@Pa with vacancies not only creates more active sites and facilitates charge redistribution, but also the improved hydrophilicity promotes the adequate contact of electrolytes with active sites, thereby enhancing the fast electrochemical reactions. As a result, the CoFe–MOF@Pa shows excellent OER performance (203 mV at 10 mA cm−2) and low Tafel slope (57.1 mV dec-1). Furthermore, CoFe–MOF@Pa&CoFe–MOF@Pa for water splitting, it only requires a cell voltage of 1.66 V without iR compensation at 10 mA cm−2. More importantly, CoFe–MOF@Pa also shows long-term activity and stability compared to pristine CoFe–MOF. This feasible strategy in this study is expected to provide insights into the preparation of efficient and robust electrocatalysts for water splitting.