Combinatorial synthesis and high-throughput photopotential and photocurrent screening of mixed-metal oxides for photoelectrochemical water splitting

Abstract

A high-throughput method has been developed using a commercial piezoelectric inkjet printer for synthesis and characterization of mixed-metal oxide photoelectrode materials for water splitting. The printer was used to deposit metal nitrate solutions onto a conductive glass substrate. The deposited metal nitrate solutions were then pyrolyzed to yield mixed-metal oxides that contained up to eight distinct metals. The stoichiometry of the metal oxides was controlled quantitatively, allowing for the creation of vast libraries of novel materials. Automated methods were developed to measure the opencircuit potentials (E oc ), short-circuit photocurrent densities (J sc ), and current density vs. applied potential (J-E) behavior under visible light irradiation. The high-throughput measurement of E oc is particularly significant because open-circuit potential measurements allow the interfacial energetics to be probed regardless of whether the band edges of the materials of concern are above, close to, or below the values needed to sustain water electrolysis under standard conditions. The E oc measurements allow high-throughput compilation of a suite of data that can be associated with the composition of the various materials in the library, to thereby aid in the development of additional screens and to form a basis for development of theoretical guidance in the prediction of additional potentially promising photoelectrode compositions.

Fulfilling the promise of the materials genome initiative with high-throughput experimental methodologies

“…7: (a) hypothesis-driven design and synthesis of a "library" sample with variations in the materials parameter(s) of interest [118][119][120][121] (typically composition); (b) rapid, local, and automated interrogation of the library for the properties of interest; 53,[122][123][124][125][126][127][128] and (c) analysis, mining, display, and curation of the resultant data. [129][130][131] Each step presents current challenges that must be overcome before HTE methodologies can be widely deployed.…”

Photoelectrocatalysis: principles, nanoemitter applications and routes to bio-inspired systems

“…Obviously, the developments in catalysis, electrocatalysis and water dissociation were historically far from being synchronized. It is not surprising that it took about 180 years before Fujishima and Honda published the first observation of light-induced water electrolysis 9 using rutile TiO 2 photoanodes, thereby strongly stimulating the field of photoelectrochemistry [10][11][12][13][14][15][16][17] that resulted in the first industrially produced photoelectrochemical device which operated in the photovoltaic mode.…”

Nanoscale Effects in Water Splitting Photocatalysis

“…Another approach involves the development of new metal oxide materials that combine suitable properties (visible band gap, high carrier mobilities, long carrier lifetimes) with greater chemical stability for photoelectrochemical water splitting. Such materials can be made by directed synthesis, sometimes guided by theory [47], or they can be made by combinatorial approaches, as described by Bruce Parkinson [48][49][50], Eric McFarland [51], and Nathan Lewis [52]. The third strategy is to exploit scaling laws and specific effects at the nanoscale [53][54][55][56] to overcome the limiting problems of metal oxide absorbers, such as their short electron-hole lifetimes and low mobility.…”