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.

Automated summary

This study focused on the synthesis of Ca-doped narrow bandgap BiFeO3 perovskite via a simple auto combustion method, demonstrating its excellent performance in oxygen evolution reactions (OER) and wastewater treatment. By doping Ca2+ into the structure, oxygen vacancies were created and the valence state of Fe3+ was modified. The material showed promising results in the photocatalytic reduction of Cr(VI) and exhibited enhanced electrochemical OER activities in both acidic and alkaline conditions.