Tailoring the Ca-doped bismuth ferrite for electrochemical oxygen evolution reaction and photocatalytic activity

The development of perovskite-based materials with a narrow bandgap for oxygen evolution reactions (OER) and wastewater treatment have much attention in recent years. Herein, a narrow bandgap of Ca-doped BiFeO3 (BCFO) is synthesized by a simple auto combustion method. To create oxygen vacancies by doping Ca2+ the place of Bi3+, the amount of Fe3+ valence state is changed as well. 0.15% of Ca doped BiFeO3 (BCFO-15) indicate a high content of Fe4+ state with a conduction band and valence band located at 0.615 V and 2.46 V vs. NHE, respectively. The electrochemical OER of BCFO-15 observed a lower onset potential of 2.13 V vs. RHE, in acidic with a current density of 25.64 mA cm−2. In alkaline electrolyte, onset potential was observed at 2.10 V vs. RHE, with a current density of 65.87 mA cm−2. Furthermore, the photocatalytic performance of the perovskites in aqueous solution was demonstrated through photocatalytic reduction of Cr(VI) as a model pollutant, resulting in an 89.92% reduction of 50 ppm of Cr(VI) in 210 min under the irradiation of a 35 W Xe arc lamp. These findings suggest that simple divalent doping of Ca into pure BiFeO3 results in excellent photocatalytic and electrocatalytic perovskites.