Abstract:Electrochemical technology offers an alternative solution to many environmental problems because electrons provide a versatile, efficient, cost-effective, and clean reagent. The technology includes electrocatalysis, heterogeneous photocatalysis, photoelectrocatalytic (PEC) process and so on. Birnessite electrodes were synthesized by electrochemical method in this paper. Mineral phase and morphology were studied by X-ray Diffraction (XRD) and scanning electron microscope (SEM). UV-Vis absorption spectra demonstrated that the birnessite had a significant absorption of visible light from 300 to 600 nm and a direct band gap of 2.14 eV. Moreover, the flat band potential was 1.15 V and the carrier concentration was 3.3×1019 cm-3 as evaluated by Mott-Schottky. The results demonstrate that birnessite is a great n-type visible light excitation semiconducting material. Meanwhile, a cheaper and more efficient solar cell was used to replace the traditional electrochemical devices such as electrochemical workstation, which realized an enhanced photoelectrocatalytic activity of birnessite. Methyl orange degradation rate was 90.2% at 60 min, which was higher than the sum of degradation rate of birnessitephotocatalysis (2.2%) and electrocatalysis (33.6%). Effective utilization of sunlight was realized and photoelectrocatalytic activity of birnessite was promoted. Moreover, energy was saved and the degradation efficiency was increased. Cyclic degradation showed that decrease degree of the fourth round degradation rate (86.8%) was lower than 5%, compared with the first round (90.3%), and this shows that it has a stability of long term operating. The results obtained by the authors provide a more energy saving, advantageous, and environmentally friendly technique for organic wastewater treatment in the field of environmental mineralogy.