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INVESTIGATIONS ON APPLICATION OF BiVO4 PHOTOANODE FOR GLYCEROL DEGRADATION

Rūta Baltaragytė1, Milda Malakauskaitė-Petrulevičienė2, Irena Savickaja2, Jurga Juodkazytė2, Alvydas Zagorskis1, Arūnas Ramanavičius2

1 Department of Environmental Protection and Water Engineering, Vilnius Gediminas technical university, Lithuania

2 Department of Chemical Engineering and Technology, Center for Physical Sciences and Technology, Lithuania

[email protected]

Photoelectrochemical (PEC) decomposition of organic compounds is attracting great attention from scientists and industry, because it enables to decompose various hazardous organic compounds to more environmentally friendly products. PEC system has many advantages, e.g. sustainability, because it uses sunlight energy, and flexibility - many types of organic compounds can be decomposed, moreover, this process can be coupled with production of hydrogen [1]. PEC decomposition is based on oxidation of organic compounds on the surface of photoanode under light illumination. The most widely studied photocatalysts are TiO2, ZnO, WO3, BiVO4 and Fe2O3 [2]. Bismuth vanadate (BiVO4) is a promising material, because of its ability to absorb visible light, low valence band position (2.4 V) and stability in neutral electrolytes.

In this work bismuth vanadate was used for PEC decomposition of glycerol. BiVO4 thin films were synthesized using sol-gel route and dip-coating technique. Composition and morphology of electrodes were studied using X-ray diffraction and scanning electron microscopy, respectively. Photoresponse of BiVO4 photoanode was first evaluated using cyclic voltammetry (CV) in 0.5 M Na2SO4 and 0.5 M NaCl electrolytes. Electrochemical impedance spectroscopy (EIS) measurements were performed to evaluation of charge transfer resistance of the films. Next, CV and chronoamperometric (CA) experiments were performed in 0.1 M NaCl solution with 1, 2, 3, 4 and 5 g/L of glycerol under illumination. Certain amount of charge was passed through the cell in CA experiments. After that the amount of glycerol was evaluated using Fourier-transform infrared spectroscopy (FTIR). Results of CV and CA experiments are presented in Fig. 1. It can be seen that photocurrent density was increasing with increase in concentration of glycerol. The efficiency of glycerol decomposition will be discussed at the conference.

Figure 1
Fig. 1. A) Cyclic voltammograms of BiVO4 photoanode in 0.1 M NaCl containing various concentrations of glycerol, 50 mV s-1, illumination intensity ~100 mWcm-2; B) Chronoamperograms of BiVO4 photoanode recorded in two electrode cell with Pt cathode under 1.4 V bias under chopped illumination

Acknowledgments: This project has received funding from the Research Council of Lithuania (LMTLT), agreement No S-PD-22-2

[1] Liu, D., Liu, J. C., Cai, W., Ma, J., Yang, H. B., Xiao, H., ... & Liu, B. (2019). Selective photoelectrochemical oxidation of glycerol to high value-added dihydroxyacetone. Nature Communications, 10(1), 1779.

[2] Li, Z., Luo, W., Zhang, M., Feng, J., & Zou, Z. (2013). Photoelectrochemical cells for solar hydrogen production: current state of promising photoelectrodes, methods to improve their properties, and outlook. Energy & Environmental Science, 6(2), 347-370.