Improving the photoactivity of bismuth vanadate thin film photoanodes through doping and surface modification strategies

Abstract

2 Graphical abstract HIGHLIGHTS La and Ce doping greatly improves the photoresponse of BiVO4 photoanodes for PEC water oxidation.  Ce and La doping triggers a significantly shift of the flat band potential to more negative values.  Surface modification of the pristine and doped BiVO4 photoanodes with Au nanoparticles further enhances the photocurrent.  Gold nanoparticles act solely as co-catalytic centers without a contribution from visible sensitization. ABSTRACTCurrently, one of the most attractive and desirable ways to solve the energy challenge is harvesting energy directly from the sunlight through the so-called artificial photosynthesis. Among the ternary oxides based on earth-abundant metals, bismuth vanadate has recently emerged as a promising photoanode. Herein, BiVO4 thin film photoanodes have been successfully synthesized by a modified metal-organic precursor decomposition method, followed by an annealing treatment. In an attempt to improve the photocatalytic properties of this semiconductor material for photoelectrochemical water oxidation, the electrodes have been modified (i) by doping with La and Ce (by modifying the composition of the BiVO4 precursor solution with the desired concentration of the doping element), and (ii) by surface modification with Au nanoparticles potentiostatically electrodeposited. La and Ce doping at concentrations of 1 and 2 at% in the BiVO4 precursor solution, respectively, enhance significantly the photoelectrocatalytic performance of BiVO4 without introducing important changes in either the material structure or the electrode morphology, according to XRD and SEM characterization. In addition, surface modification of the electrodes with Au nanoparticles further enhances the photocurrent as such metallic nanoparticles act as co-catalysts, promoting charge transfer at the semiconductor/solution interface. The combination of these two complementary ways of modifying the electrodes has resulted in a significant increase in the photoresponse, facilitating their potential application in artificial photosynthesis devices.

Experimental and Computational Investigation of Lanthanide Ion Doping on BiVO4 Photoanodes for Solar Water Splitting

“…21 Compared to investigations of vanadium and oxygen sites of monoclinic BiVO4, studies on the composition tuning of Bi sites have been relatively empirical; although changes in properties were reported after Bi-site doping, no elucidations have been made regarding how the dopants caused the observed modifications. [22][23][24][25][26] To accurately elucidate the doping effect on the Bi site, confirmation of dopant incorporation in the lattice must be obtained first, so as to exclude the case of dopants accumulating at the surface. Another important prerequisite for a rigorous doping study is to ensure that the pristine and doped samples have comparable morphologies.…”

Core-substituted naphthalenediimides anchored on BiVO4 for visible light-driven water splitting

“…[11][12][13][14][15] Morphology control (heterojunction, homojunction, nanocasting, etc.) [16][17][18] and doping techniques [19][20][21][22] have been investigated with the aim to enhance the BiVO4 photocatalytic efficiency by improving both surface area and electron/hole mobility, which are necessary to minimize recombination loses and facilitate the superficial charge transfer.…”

Controlling the amount of co-catalyst as a critical factor in determining the efficiency of photoelectrodes: The case of nickel (II) hydroxide on vanadate photoanodes

“…BiVO4 thin film photoanodes were obtained following the same procedure described above, but incorporating the doping element in the BiVO4 precursor solution at the desired concentration (in at% with respect to either Bi or V content) [70]. In this case,…”