Formation energy and photoelectrochemical properties of BiVO₄after doping at Bi³⁺or V⁵⁺sites with higher valence metal ions

Abstract

Photoelectrochemical water splitting is an attractive method to produce H(2) fuel from solar energy and water. Ion doping with higher valence states was used widely to enhance the photocurrent of an n-type oxide semiconductor. In this study, the different doping sites and the photoelectrochemical properties of Mo(6+), W(6+) and Sn(4+)-doped BiVO(4) were studied systematically. The results suggested that Mo(6+) or W(6+)-doped BiVO(4) had a much higher photocurrent while the photocurrent of Sn(4+)-doped BiVO(4) did not change obviously. Raman and XPS were used to identify the doping sites in the BiVO(4) crystal lattice. It was found that Mo or W substituted V sites but Sn did not substitute Bi sites. Results of theoretical calculation indicated that a higher formation energy and lower solubility of impurity ions led to serious SnO(2) segregation on the surface of the Sn(4+)-doped BiVO(4) thin film, which was the main reason for the poor performance of Sn-doped BiVO(4). The higher formation energy of Sn(4+) came from the large mismatch of ion radius and different outer shell electron distribution. These results can offer guidance in choosing suitable doping ions for other semiconductor photoelectrodes.

Textured nanoporous Mo:BiVO4 photoanodes with high charge transport and charge transfer quantum efficiencies for oxygen evolution

“…Such Mo-free, textured samples are designated ''noMo/T'' films. To assess the impact of incorporating molybdenum, an impurity known to improve the photocurrent of BiVO 4 electrodes, 18,21,26,30,31,33,34,37,40,42 we added Mo to untextured and textured BVO films (making ''Mo/U'' and ''Mo/T'' films, respectively) by spiking the spin coating solution with 2 at% MoO 2 (acac) 2 (see Experimental and Fig. 1c-e).…”

Quantitative Analysis and Visualized Evidence for High Charge Separation Efficiency in a Solid‐Liquid Bulk Heterojunction

“…[ 36 ] Bi(NO 3 ) 3 ·5H 2 O in glacial acetic acid (0.2 mol L −1 ), vanadylacetyl acetonate in acetylacetone (0.03 mol L −1 ) and Molybdenyl acetylacetonate in acetylacetone (0.01 mol L −1 ) were used as starting solutions. Proper amount of these solutions were well mixed together according to the stoichiometric ratio of Bi : V : Mo as 100 : 97 : 3, then dropped on FTO substrates (1 cm 2 × 1.5 cm 2 ), dried and then calcined at 470 °C in a muffl e furnace for 30 min to form BiVO 4 :Mo fi lms.…”

Efficient visible light-driven water oxidation and proton reduction by an ordered covalent triazine-based framework

“…14,15 Metal-oxide photocatalysts have been widely studied in water oxidation, such as BiVO 4 , which shows very promising activity, though there is a concern about the heavy metal Bi used and difficulty in changing its band positions. 6,8,16,17 For polymer based photocatalysts, up to now, there are many reports about proton reduction by either g-C 3 N 4 or g-C 3 N 4 doped by oxygen, boron, phosphorus, etc. 6,9,[18][19][20][21] For example, Wang et al reported that graphitic carbon nitride presents great potential for photocatalytic proton reduction in 2009 and platinum decorated g-C 3 N 4 shows ca.…”