Combinatorial Synthesis and High-Throughput Characterization of Fe–V–O Thin-Film Materials Libraries for Solar Water Splitting

Abstract

The search for suitable materials for solar water splitting is addressed with combinatorial material science methods. Thin film Fe-V-O materials libraries were synthesized using combinatorial reactive magnetron cosputtering and subsequent annealing in air. The design of the libraries comprises a combination of large compositional gradients (from FeVO to FeVO ) and thickness gradients (from 140 to 425 nm). These material libraries were investigated by high-throughput characterization techniques in terms of composition, structure, optical, and photoelectrochemical properties to establish correlations between composition, thickness, crystallinity, microstructure, and photocurrent density. Results show the presence of the FeVO phase from ∼11 to 42 at. % Fe (toward low-Fe region) and the FeVO phase from ∼37 to 79 at. % Fe (toward Fe-rich region). However, as a third phase, FeO is present throughout the compositional gradients (from low-Fe to Fe-rich region). Material compositions with increasing crystallinity of the FeVO phase show enhanced photocurrent densities (∼160 to 190 μA/cm) throughout the thickness gradients whereas compositions with the FeVO phase show comparatively low photocurrent densities (∼28 μA/cm). The band gap energies of Fe-V-O films were inferred from Tauc plots. The highest photocurrent density of ∼190 μA/cm was obtained for films with ∼54 to 66 at. % Fe for the FeVO phase with ∼2.04 eV for the indirect and ∼2.80 eV for the direct band gap energies.

Overcoming Phase‐Purity Challenges in Complex Metal Oxide Photoelectrodes: A Case Study of CuBi2O4

“…[17,18] This exciting prospect has generated extensive high-throughput and combinatorial efforts to accelerate the discovery and study of new complex metal oxides photo absorbers for solar water splitting. [19][20][21][22][23][24] However, with rapidly increasing efforts toward finding new ideal compositions of photoabsorbers with enhanced properties, the number of different cations is very probable to increase. The cations may vary widely in size, oxidation state, and vapor pressure under heating treatment conditions.…”

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

“…Several groups have reported the fabrication of FeVO 4 thin films using magnetron cosputtering, spray pyrolysis, dropcasting, and sol-gel methods with reported bandgap energy of 2.0-2.1 eV. [21][22][23][24][25][26][27][28][29][30][31] However, the achieved photocurrents are still very low as compared with the theoretical photocurrent based on the bandgap energy. We have previously identified that the main problem causing the low performance of FeVO 4 films is the poor bulk carrier separation.…”

Discovery of new materials using combinatorial synthesis and high-throughput characterization of thin-film materials libraries combined with computational methods

“…In this system it was found by high-throughput experimentation and ab initio calculations that the addition of Cu improves the alloy properties. 21 (copyright ACS Publications, 2014), 49 (copyright ACS Publications, 2017), 58 (copyright ACS Publications, 2017), 59 (copyright Elsevier, 2012), 60 (copyright ACS Publications 2018) and 37 (copyright RCS, 2018)…”