Thermochemical two-step water splitting by ZrO2-supported NixFe3−xO4 for solar hydrogen production

Functioning devices for solar to fuel conversion

“…Both systems require the quenching of the reduction products in order to prevent re-oxidation. Although the feasibility of the iron oxide based cycle has been demonstrated [73,75], the thermodynamic requirements (operating temperature for the thermal reduction >1800 • C) in combination with the material properties (melting temperatures of FeO around 1400 • C [76]) prohibit the development of possible processing schemes. The use of mixed metal ferrites (with Mn, Ni, Zn) lowers the temperature of the activation step and avoids phase transformations [77][78][79][80].…”

Modelling of solar thermochemical reaction systems

“…These calculations can provide great insight into mechanisms of the reaction pathway and the material properties that can limit or enhance active material performance. Recent works using DFT calculations to elucidate design principles for improved solar thermochemical cycle active materials have suggested that the thermodynamics of forming oxygen vacancies in a metal oxide lattice and the kinetics of conducting those vacancies (Kodama et al, 2008;Gokon et al, 2011;Kodama et al, 2005;Rydén et al, 2011;Alvani et al, 2005;Tamaura et al, 1998;Hwang et al, 2004;Miller et al, 2008;Fresno et al, 2009;Fresno et al, 2010;Arifin et al, 2012;Gokon et al, 2008b;Agrafiotis et al, 2015;Agrafiotis et al, 2012;Goikoetxea et al, 2016;Lorentzou et al, 2014;Cha et al, 2007;Kodama et al, 2002) to and from the surface are important in assessing material activity (Michalsky et al, 2015a,b;Ezbiri et al, 2015). Indeed, a study data mining first principles data from doped ceria studies identified surface oxygen vacancy formation energy as the primary descriptor that correlates with enhanced water splitting ability (Botu et al, 2016).…”

“…The studies on ferrite-based systems have shown that required reduction temperatures can be lowered by substituting metals such as manganese or nickel into ferrite based mixed metal oxides of the type M x Fe 3-x O 4 (Steinfeld, 2005). Co, Ni, Zn, Cu, and Mn substitutions into ferrite spinel structures have recently been used in successful hightemperature H 2 O/CO 2 splitting, suggesting that the M x Fe 3-x O 4 form of these mixed oxides is particularly active (Kodama et al, 2008;Gokon et al, 2011;Kodama et al, 2005;Rydén et al, 2011;Alvani et al, 2005;Tamaura et al, 1998;Hwang et al, 2004;Miller et al, 2008;Fresno et al, 2009;Fresno et al, 2010;Arifin et al, 2012;Gokon et al, 2008b;Agrafiotis et al, 2015;Goikoetxea et al, 2016;Lorentzou et al, 2014;Cha et al, 2007;Kodama et al, 2002). Other spinel structures are also of interest, such as the ''hercynite cycle" (Muhich et al, 2013 (Haussener et al, 2010c).…”

Effects of Dopant Metal Variation and Material Synthesis Method on the Material Properties of Mixed Metal Ferrites in Yttria Stabilized Zirconia for Solar Thermochemical Fuel Production

“…This adversely affects the reactivity of the redox material. Previous work has shown that ferrite particles supported by zirconium oxide (ZrO 2 ) exhibit a lesser degree of sintering and thus greater cycling longevity [15,16]. Yet, the inclusion of ZrO 2 presents a new issue.…”

“…Ferrites doped with Ni, Mn, or Co have exhibited an increase in reaction rates and have required lower temperatures for reduction [16,[23][24][25]. Moreover, these doped ferrites tend to have higher melting points, thus lowering the rate of sintering during the reduction step [26].…”