The boosting electrocatalytic OER and 4-nitrophenol oxidation over bimetallic ZIF-67/Fe2O3 p-n conjunction: Experiments and DFT calculations

In the Co/Cu-ZIF/Fe2O3 p-n junction, the electrons flow from n-type Fe2O3 to p-type bimetallic Co/Cu-ZIF, resulting in the band bending and inner electric field from positive Fe2O3 to negative Co/Cu-ZIF. The density function theory calculation uncovered that such an electronic property change could boost the water oxidation performance. Experiments reveal that the obtained Co/Cu-ZIF(1/1)/Fe2O3 heterojunction achieves a low overpotential of 273 mV and a small Tafel slope of 133.6 mV·dec-1 at 10 mA·cm-2 current density, which are significantly lower than that of monometallic Co-ZIF and FC substrate. Moreover, the p-n conjunction can promote the electrocatalytic degradation of 4-nitrophenol, and the removal rate reaches 80%, current efficiency (23.97%) and low energy consumption (79.5 Wh·L-1) at 50 mA·cm-2. Therefore, it is expected that MOFs-based p-n conjunction with modulation of electron configuration is a promising alternative to boost the electrochemical water oxidation.