Enhanced photoelectrochemical and photocatalytic properties of Mg-doped ZnMn2O4

Mg-doped spinel ZnMn2O4 was prepared by a facile sol-gel method. The textural, electrochemical and photocatalytic properties of the as-prepared compounds were investigated. The specific surface area and the porosity increase drastically with Mg content reaching 71 m2 g−1 and 23% for x = 0.1, respectively. The pore radii were mostly in the range of 7–14 nm. The electrochemical study revealed that the stability against photocorrosion increased with Mg-doping. In addition, the photocurrent (Jph) increased from 8.33 10-2 to 75.01 10-2 mA cm-2. On the other hand, the electrochemical impedance spectroscopy revealed that the recombination through the semiconductor limited the efficiency. The photoactivity gradually increased with increasing the dopant content, and 72% of photodegradation efficiency was obtained with Mg0.1-ZnMn2O4 catalyst toward Methylene Blue (MB) removal. The highest photocatalytic degradations of MB (>95%) were obtained in less than 120 min under the following optimized conditions: catalyst content 1 g L-1, 30 ppm of MB concentration, pH 10, and light flux of 102.06 10−5 kW. Under these conditions, the electrical energy per order (EEO) of 25.20 kW h m−3 was obtained. The total mineralization of MB was achieved in less than 250 min using Mg0.1-ZnMn2O4 as a catalyst under visible light. [Display omitted] •Mg-doped spinel ZnMn2O4 was prepared by a facile sol-gel method.•Specific surface area and porosity increase drastically with Mg content.•The catalysts showed stability against corrosion.•Mg-doping increases the photocurrent (Jph) of ZnMn2O4.•Mg0.1-ZnMn2O4 is the most active catalyst toward Methylene Blue removal.