Advances in the Development and morphological arrangement of Bismuth-Based Nanoparticles for Photoelectrocatalytic water splitting. BiVO4 : Synthesis, structural features and photoelectrocatalytic water splitting applications

Abstract

Hydrogen gas has the potential to be used as an alternative form of fuel replacing non-renewable fuels which are depleting rapidly. Conventional method for hydrogen generation involves methane steam reforming producing CO₂ as a by-product, this method involves high cost of production and immense amount of toxic environmental pollutants. Photo electrocatalytic (PEC) water splitting has gained a lot of attention in the past decade as is an efficient and economical method for producing hydrogen in an environmentally friendly manner.  Various semiconductor materials (TiO_2, ZnO, CdS and Fe₂O₃) have been used for PEC applications, but they posses two main drawbacks which includes its large energy bandgap and low rate of photo generated electron hole recombination. Bismuth based nanomaterials have attained considerable attention for PEC applications due to its low cost, high stability, minimal toxicity and high photocatalytic performance. This project aims to synthesize bismuth molybdate, bismuth vanadate and bismuth tungstate to study its photoelectrocatalytic water splitting application and document its efficiency and feasibility.

Hydrothermal method of synthesis was used to synthesize bismuth vanadate, bismuth molybdate and bismuth tungstate by using the suitable percursors for the three compounds. Hydrothermal synthesis involves a Teflon tube containing the reaction mixture enclosed in a steel autoclave. The autoclave was then subjected to heating in a hot air oven for a known time. The autoclave was removed from the hot air oven and cooled naturally to room temperature. After cooling the final product was recovered by centrifuging and drying. The obtained nanoparticles were characterized by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy to obtain the crystal structure, size, electronic state of elements and chemical composition. From the characterization, the prepared product was further investigated for photoelectrocatalytic water splitting applications. 

After X-ray diffraction (XRD) characterization it was confirmed that the synthesized compound is bismuth molybdate, bismuth vanadate and bismuth tungstate. From the XRD results, it was observed that the peaks present in the graph of intensity vs. 2θ were in accordance with that available in the standard literature. From this project, Its concluded that the hydrothermal method of synthesis is an efficient process for synthesis of bismuth molybdate, bismuth vanadate and bismuth tungstate. These prepared bismuth-based nanoparticles hold great potential in photoelectrocatalytic applications.