New synthesis method for ternary metal oxide photoelectrodes

©  C. Lhermitte /  2020 EPFL

© C. Lhermitte / 2020 EPFL

Dr. Charles Lhermitte et al. of the LIMNO lab report the development of a mild but versatile method for thin-film synthesis as a “Very Important Paper” in ChemSUSChem.

Developing facile and environmentally friendly approaches to prepare semi-transparent ternary oxide thin film photoelectrodes is an important goal for solar fuel production via the photoelectrochemical water splitting tandem cell. However, different materials typically require very different synthesis conditions, and these conditions often require harsh solvents and processing. Herein the LIMNO lab reports a novel synthesis route that employs ethylenediamine tetra-acetic acid (EDTA) to enable compatible water solubility of diverse metal cations, which affords transparent films via solution processing. Using BiVO4 as a model material, we demonstrate a remarkable improvement in transparency quantified by the direct transmittance at 600 nm of >80% vs. the < 10% observed with state-of-the-art electrodeposited thin films while maintaining reasonable solar-driven oxidation photocurrents (1.75 mA cm-2 in the presence of a sulphite hole scavenger). Furthermore, we demonstrate that the synthesis technique can be applied in a general fashion towards the synthesis of diverse n- and p-type metal oxide materials, such as ZnFe2O4 and CuFeO2. The paper detailing the results, published in ChemSUSChem, was chosen as a Very Important Paper by the editors, based on the enthusiasm of the reviewers. Indeed, this improvement will help to rapidly advance the field of ternary oxide thin film photoelectrodes.