Electrochemical Study of Semiconductor Properties for Bismuth Silicate-Based Photocatalysts Obtained via Hydro-/Solvothermal Approach

Abstract

Three bismuth silicate-based photocatalysts (composites of Bi2SiO5 and Bi12SiO20) prepared via the hydro-/solvothermal approach were studied using electrochemical methods. The characteristic parameters of semiconductors, such as flat band potential, donor density, and mobility of their charge carriers, were obtained and compared with the materials’ photocatalytic activity. An attempt was made to study the effect of solution components on the semiconductor/liquid interface (SLI). In particular, the Mott–Schottky characterization was made in a common model electrolyte (Na2SO4) and with the addition of glycerol as a model organic compound for photocatalysis. Thus, a medium close to those in photocatalytic experiments was simulated, at least within the limits allowed by electrochemical measurements. Zeta-potential measurements and electrochemical impedance spectroscopy were used to reveal the processes taking place at the SLI. It was found that the medium in which measurements were carried out dramatically impacted the results. The flat band potential values (Efb) obtained via the Mott–Schottky technique were shown to differ significantly depending on the solution used in the experiment, which is explained by different processes taking place at the SLI. A strong influence of specific adsorption of commonly used sulfate ions and neutral molecules on the measured values of Efb was shown.

Constructing Heterogeneous Photocatalysts Based on Carbon Nitride Nanosheets and Graphene Quantum Dots for Highly Efficient Photocatalytic Hydrogen Generation

“…[ 4 , 5 , 10 , 11 , 12 ]. However, many of the semiconductor materials have a limited visible light-absorption range, due to the large band gaps caused by the usage of sunlight [ 13 , 14 , 15 , 16 , 17 ]. Additionally, the poor separation efficiency and rapid recombination of the photoinduced electron–hole pairs are other important factors limiting photocatalytic hydrogen production [ 18 , 19 , 20 , 21 ].…”

Bismuth Silicate/Silica-Titania Synthesis from In Situ Decomposition of Oil Palm Leaves as Silica Source

“…For example, melting (Lu et al, 2013;Back et al, 2020), mechanical (Belik et al, 2020) , hydrothermal (Jia et al, 2017) , and sintering (Bai et al, 2007) processes were developed for the purposes of reactions. Another synthetic method developed for bismuth silicate is using the hydro-/solvothermal form Bi(NO 3 ) 2 and commercial silica sources (Shabalina et al, 2022) . As can be extracted from the literature on bismuth silicate compounds synthesis, the pres-ence of SiO 2 is very important.…”