Tuning Light‐Driven Water Splitting Efficiency of Mo‐Doped BiVO₄: Optimised Preparation and Impact of Oxygen Evolution Electrocatalysts

Abstract

We present airbrush spray-coating as a reproducible method for the preparation of Mo-doped BiVO 4 (Mo : BiVO 4 ) as photoabsorber with different layer thicknesses and Mo content. Optimisation of layer thickness is aiming on diminishing limitations by the electronic conductivity within the photoabsorber, thus increasing the incident photon to current efficiency (IPCE) of the samples. Furthermore, the Mo to V ratio leading to the highest photocurrent density was determined, and the optimised Mo : BiVO 4 samples were decorated with a variety of oxygen evolution reaction (OER) electrocatalysts such as cobalt phosphate and layered double hydroxides. A mass loading gradient of NiÀ Fe LDH was sprayed on top of the Mo : BiVO 4 photoanode for optimisation of the OER catalyst loading. The photocurrent density was enhanced by up to 5.8 times at 0.8 V vs. RHE in comparison with the pristine Mo : BiVO 4 sample in absence of any OER electrocatalyst.[a] J.

Tuning Light‐Driven Water Oxidation Efficiency of Molybdenum‐Doped BiVO4 by Means of Multicomposite Catalysts Containing Nickel, Iron, and Chromium Oxides

“…Then, a second layer was deposited containing either a suspension of Ni, Fe, and Cr oxides or a mixture of Mo:BiVO 4 precursors and Ni, Fe, Cr oxides. It is important to note that the deposition of an additional Mo:BiVO 4 layer without the addition of the multicomposite catalyst did not cause an increase in photoelectrochemical activity, in agreement with previous reports . Using this method of preparation, we were able to obtain samples with different morphology and properties, but without drastically changing the structure of the photoabsorber when including the catalyst in either of the two configurations, i. e., as a top layer or embedded within the Mo:BiVO 4 film.…”

“…In order to prepare Mo:BiVO 4 samples modified with the catalyst, photoactive films where deposited by means of a spray‐coating setup onto FTO substrates followed by heat treatment. First a standard layer of Mo:BiVO 4 was deposited as described in ref . Then, a second layer was deposited containing either a suspension of Ni, Fe, and Cr oxides or a mixture of Mo:BiVO 4 precursors and Ni, Fe, Cr oxides.…”

“…Mo‐doped bismuth vanadate electrode preparation : FTO glass substrates (1.5×2.5 cm 2 ) were cleaned with a 10 g L −1 Alconox® solution, rinsed with deionised water and ethanol, and dried under argon flow. The spray procedure for Mo‐doped BiVO 4 samples was adapted from ref …”

“…Here, we present the modification of an optimised Mo‐doped BiVO 4 (Mo:BiVO 4 ), with a Ni, Fe, and Cr oxides containing multicomposite catalyst providing enhanced O 2 evolution activity, using two different configurations, namely with either the catalyst deposited on top or embedded into the Mo:BiVO 4 film. We show that, although the same catalyst is used, its integration within the photoanode material using the two different configurations leads to significantly different results.…”

Probing the local activity of CO2 reduction on gold gas diffusion electrodes: effect of the catalyst loading and CO2 pressure

“…The ink was deposited on the substrate using the spray-coating apparatus previously described. 28,29 The H23C2 substrates were placed on a heating block at 100 °C for quickly evaporating the solvent, hence reducing the possible formation of agglomerates. A template was used to limit the sprayed area to 1 x 3 cm.…”