High Throughput Discovery of Effective Metal Doping in FeVO₄ for Photoelectrochemical Water Splitting

Abstract

FeVO4 is a potential photoanode candidate with favorable bandgap energy for absorbing visible light in the solar spectrum. However, the achieved photocurrents are still much lower than the theoretical photocurrent due to poor bulk carrier separation efficiency. Herein, the aim is to improve FeVO4 charge transport properties by searching for suitable metal doping using combinatorial methods. Thin‐film FeVO4 libraries with different doping ratios of Zn, Ni, Cr, Mo, and W are fabricated on fluorine doped tin oxide substrates using combinatorial inkjet printing and their photoelectrochemical properties screened using photoscanning droplet cell. Mo and W doping show higher current density compared with undoped FeVO4; whereas the photocurrent decreases for Ni‐ and Zn‐doped samples. The best photocurrent is achieved with 7% doping ratio of Cr. Cr is discovered as a promising dopant for the first time, which is more effective than reported Mo or W for FeVO4 photoanode. The replacement of Cr3+ to Fe3+ in FeVO4 crystal lattice helps to mainly improve the catalytic activity for charge transfer, which results in the enhancement of photoresponse of the FeVO4 photoanode.

High throughput discovery of enhanced visible photoactivity in Fe–Cr vanadate solar fuels photoanodes

“…Unlike M = (Bi, Fe), complete miscibility on the M +3 sublattice has been observed for M = (Cr, Fe), with cation ordering at the 1:1 composition resulting in the quaternary oxide CrFe(VO) 4 [35]. Similar miscibility has been observed in the M 2 V 4 O 13 system [36], motivating our exploration of Cr-Fe-V oxide photoanodes with substantial amounts of both Cr and Fe, as opposed to the more dilute-substitutions that were explored previously [27]. Since the path for outperforming BiVO 4 -based materials commences with establishing substantial photoactivity between 2 and 2.4 eV, we investigate the spectrally-resolved compositional variation in photoactivity, demonstrating that compositions near (Cr 0.5 Fe 0.5 )VO 4 are optimal for photoactivity at both 2.1 and 2.4 eV, motiving future study of these quaternary oxides to efficiently utilize the solar resource and advance solar fuels technologies.…”

“…The cation-substitution strategy for improving the photoactivity of FeVO 4 was initially demonstrated via doping with W [18] or Mo [22] and was more explored using combinatorial synthesis and screening methods by Nguyen et al [27]. Cation substituents explored in that work include Zn, Ni, Cr, Mo, and W with cation concentrations up to 10%.…”

Enhancing Photoelectrochemical Performance of the Printed Nanoporous FeVO4 Photoanode by Dual-Layer CoOx–CoPi Catalysts

“…The sample exhibits typical diffraction peaks at 25.09°and 27.75°corresponding to the triclinic FeVO 4 , which is consistent with previous reports. 20,25 No other impurity phases are seen, except the peaks of SnO 2 from the FTO substrate. The XRD patterns of other fabricated films that annealed at the lower annealing temperatures (550−400 °C) are presented in Figure S1.…”

“…into the FeVO 4 film, the bulk carrier separation efficiency was improved, but it is still lower than 0.5% (1.0 V vs RHE). 25 Consequently, more research studies are required to enhance bulk carrier separation. Morphology modification or nanostructuring is a promising approach to solving the poor carrier transport problem.…”

Angle-independent solar radiation capture by 3D printed lattice structures for efficient photoelectrochemical water splitting

“…photo-anodes/cathodes to align with the energetics of the water splitting reaction. [3][4][5][6][7][8] Some of the works also focus on the stability of these semiconductors 9,10 and on finding a suitable catalyst that can enhance the functioning of these photoanodes/cathodes. [11][12][13] These approaches are primarily driven by the search for novel materials.…”