The Role of PEG 6000 and PVP as Stabilizing and Surfactant Agents in the Photoelectrochemical Properties of BiVO4 Monoclinic Structure

Marcelo Pelissari,Luiz Henrique Dall’Antonia,Luis Vicente Scalvi

doi:10.21577/0103-5053.20210076

Marcelo Pelissari, Luiz Henrique Dall’Antonia + Show 1 more

Open Access

https://doi.org/10.21577/0103-5053.20210076

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Abstract

Nanocrystalline BiVO4 on monoclinic phase was obtained by a modified-solution combustion synthesis (SCS) using poly(ethylene glycol) (PEG 6000) and polyvinylpyrrolidone (PVP) as stabilizing and surfactant agents, respectively. An active photoanode was built using a simple procedure by dip-coating deposition process on fluorine-doped tin dioxide (FTO). The structure, morphology and optical properties of FTO/BiVO4 photoanode were evaluated by means of X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM) and diffuse reflectance UV-Vis spectroscopy. The photoelectrochemical performance measurements were carried out by linear sweep voltammetry (LSV), chronoamperometry and electrochemical impedance spectroscopy (EIS) under InGaN blue light emitting diode (LED) illumination condition (about 450 nm). In Na2SO4 electrolyte solution, the electrode has presented better photoelectroactivity than in NaNO3 solution, as evidenced by photoelectrochemical parameters such as: the highest photocurrent density (js) value, cathodic shifts of the onset potential (OP) and lower charge-transfer resistence (Rct). In the methyl orange (MO) degradation reaction the FTO/BiVO4 electrode has presented high photoelectroactivity, where the estimated kinetic constant rate (kobs) is 4.74 × 10−3 and 7.54 × 10−3 min−1 in NaNO3 and Na2SO4 solutions, respectively. This remarkable performance of the as-prepared electrode is due to the morphological BiVO4 structure,with elongated-shape nano-sized domain particles, besides the considerable porosity and roughness levels on electrode surface.

Highlights

Monoclinic bismuth vanadate (BiVO4) structure in the thin films configuration presents high technological potential, and may be used as electrode material, playing as photoanode in a wide range of systems.[1]
PVP does not appear in equation 1 and, in addition to stabilizing agent role, it plays a fundamental role as surfactant agent, acting as viscosity regulator in the solution.[25]
A shift of 100 mV to more cathodic potential is observed in Na2SO4 solution compared to NaNO3 solution, showing a better photoelectrochemical where jt is the photocurrent at time t, the transient decay time is defined as the time at which ln D = −1.44-47 The estimated values of decay time for the sample BiVO4 (4) are 10.70 and 17.22 s in Na2SO4 and NaNO3, respectively

Summary

Introduction

Monoclinic bismuth vanadate (BiVO4) structure in the thin films configuration presents high technological potential, and may be used as electrode material, playing as photoanode in a wide range of systems.[1]. The Raman shift (Figure 1b), shows that the average V-O bond length evaluated for this sample is 1.696 Å, which is little larger than for the other samples, and may cause a relaxed state in this V-O bond, which favors the enhancement of the activity of oxygen evaluation reaction.[39,41] In addition, and maybe the most important parameter due to its direct relation with the photoelectrochemical properties, is the homogeneity distribution, which in the case of sample BiVO4 (4) consists of particles with rods-shape format and nano-sized domain on the electrode surface, as can be seen in the SEM images in the Figure 2d.

Results

Conclusion