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/Fe 2 O 3 p-n junction, the electrons flow from n-type Fe 2 O 3 to p-type bimetallic Co/Cu-ZIF, resulting in the band bending and inner electric field from positive Fe 2 O 3 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)/Fe 2 O 3 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. [Display omitted] • The monolithic electrode of Co/Cu-ZIF/Fe 2 O 3 p-n junction integrated OER and oxidation of 4-NP. • The doping of second Cu center induced the high-valence Co3+ active sites and the O-containing intermediates. • The band bending and Co3+ led to charge redistribution and electron transfer, boosting the electrocatalytic activities. [ABSTRACT FROM AUTHOR]