Integration of Molybdenum-Doped, Hydrogen-Annealed BiVO₄ with Silicon Microwires for Photoelectrochemical Applications

Abstract

H-BiVO4–x:Mo was successfully deposited on microwire-structured silicon substrates, using indium tin oxide (ITO) as an interlayer and BiOI prepared by electrodeposition as precursor. Electrodeposition of BiOI, induced by the electrochemical reduction of p-benzoquinone, appeared to proceed through three stages, being nucleation of particles at the base and bottom of the microwire arrays, followed by rapid (homogeneous) growth, and termination by increasing interfacial resistances. Variations in charge density and morphology as a function of spacing of the microwires are explained by (a) variations in mass transfer limitations, most likely associated with the electrochemical reduction of p-benzoquinone, and (b) inhomogeneity in ITO deposition. Unexpectedly, H-BiVO4–x:Mo on microwire substrates (4 μm radius, 4 to 20 μm spacing, and 5 to 16 μm length) underperformed compared to H-BiVO4–x:Mo on flat surfaces in photocatalytic tests employing sulfite (SO32–) oxidation in a KPi buffer solution at pH 7.0. While we cannot exclude optical effects, or differences in material properties on the nanoscale, we predominantly attribute this to detrimental diffusion limitations of the redox species within the internal volume of the microwire arrays, in agreement with existing literature and the observations regarding the electrodeposition of BiOI. Our results may assist in developing high-efficiency PEC devices.

Organosilicon uptake by biological membranes

“…For AES and IR, gold-coated substrates were used. ITO and gold coatings were deposited in the cleanroom of the MESA+ Institute for Nanotechnology by sputtering a layer of ∽100 nm on fused-silica substrates 41 . Thereafter, substrates were cut by dicing to a size of 1 × 1 cm 2 .…”

Stable and efficient self-sustained photoelectrochemical desalination based on CdS QDs/BiVO4 heterostructure

“…As seen from the enlarged view of the dominant peak at 830 cm -1 in Fig. S2b, after doping with Mo, the Ag mode of V-O bond shifts to lower frequency which is interpreted as an increase of V-O bond lengths by a substitution of Mo for V into the lattice of BiVO 4 [61,62]. Moreover, the Bg stretching mode of V-O at 712 cm -1 is related to the oxygen vacancies.…”

In-plane synthesis of silicon microwires array for optoelectronic and microelectronic applications; a TCAD study

“…The resulting device shows improved photoelectrochemical performance compared to the individual components. The presented experimental results demonstrate the effectiveness of the method and the potential of the integrated BiV O 4 /Si MW device for solar water splitting and other photoelectrochemical applications [13]. Si MW photocathodes with a nickel silicide interlayer were used in strongly alkaline solutions for energy conversion technologies.…”