BiVO4-Polyoxometalate Composite Film Photoanode for Photoelectrochemical Phenol Sensing
Authors: Xu Lin , Zhang Qian 
Published: May 2020

Currently widespread environmental pollutants have caused serious risks to the health of living things and humans. In particular, various toxic pollutants resulting from industrial factories were constantly discharged into environment. Phenol is natural or anthropogenic origin and usually obtained from petroleum or coal tar and are widely used in chemical, petro-chemical as well as pharmaceutical industries. Phenol as pollutant in water is also related with these industrial processes. The presence of phenols in the environment creates health concerns due to their toxicity; e.g., phenol is acting corrosively in contact with skin and mucosal membranes. Also, phenol is highly water-soluble leading to increased environmental risks. Therefore, it is vital to develop a facile and efficient analysis method to detect phenol concentration in aqueous solution. Photoelectrochemical sensing is a new-fashioned analytical method, which may find promising application in sensing in virtue of its high response, low cost and easy fabrication.
Recently, bismuth vanadate (BiVO4) as an n-type semiconducting material of narrow band gap has attracted wide attention owing to its superior properties of non-toxic, low-cost, high stability and excellent photoelectrochemical performance. Polyoxometalates (POM), a class of molecular metal-oxo cluster compounds based mainly on Mo, W, and V elements, have shown promising application prospect in fields of catalysis, medicine, and materials science owing to their superior physicochemical properties. Especially, POM clusters can act as efficient electron acceptor dopant in semiconductor composite materials, and then POM have the ability to capture and transport photogenerated electrons from the conduction band (CB) of semiconductor; this thus reduces the electron-hole recombination and enhances photoelectric conversion efficiency of semiconductor materials.
In this work, combining the advantages of both BiVO4 and POM, we prepared the BiVO4/PW12 composite film photoanode, and investigated its performance for photoelectrochemical phenol sensing. Bismuth vanadate nanotubes were prepared by heating reflux method. PW12 was introduced to BiVO4 and BiVO4/PW12 composite film electrode sensors by means of electrodeposition. At room temperature, a three-electrode system was used to test the concentration of phenol in the sensing solution by using BiVO4 and BiVO4/PW12 composite film electrodes as working electrodes. Through the experiment, it was found that both BiVO4 and BiVO4/PW12 sensor composite film electrodes were responsive to the concentration of phenol in solution. The BiVO4/PW12 composite film sensor showed excellent performance of sensing phenol concentration in aqueous solution, and the linear correlation reached 99.16%. When the concentration of phenol was 100 mg•L, the response of BiVO4/PW12 composite film electrode to the solution was 1.778, which was about 3.6 times higher than that of the pure BiVO4 electrode. The results from this work show an effective photoelectrochemical sensing method of phenol detection.

Figure 1