Solar hydrogen production by two-step thermochemical cycles: Evaluation of the activity of commercial ferrites

Functioning devices for solar to fuel conversion

“…Many redox pairs have been considered in the past [10,68,69]. It was concluded that the most feasible pairs are the ZnO/Zn as well as Fe 3 O 4 /FeO redox cycles [69], having theoretical energy efficiencies of up to 82% [10] and 76% [70], respectively, considering a complete heat recovery from the quenching procedure.…”

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).…”

Hydrogen production via thermochemical water splitting

“…With respect to materials composition, the current consensus seems to be that among the many ferrite materials tested for the targeted application, Zn-containing ones exhibit Zn-volatilization problems and Mn-containing ones have phase stability problems under air atmosphere at high temperatures (Agrafiotis et al, 2012;Fresno et al, 2009;Rosmaninho et al, 2011;Tsuji, Togawa, Wada, Sano, & Tamaura, 1995). These facts leave only NiFe 2 O 4 and CoFe 2 O 4 as the most robust ferrites capable of operating reliably at the real conditions of a solar-aided process.…”