Abstract
Variable valence oxides of the perovskite crystal structure have emerged as promising candidates for solar hydrogen production via two-step thermochemical cycling. Here, we report the exceptional efficacy of the perovskite CaTi0.5Mn0.5O3–δ (CTM55) for this process. The combination of intermediate enthalpy, ranging between 200 and 280 kJ (mol-O)−1, and large entropy, ranging between 120 and 180 J (mol-O)−1 K−1, of CTM55 create favorable conditions for water splitting. The oxidation state changes are dominated by Mn, with Ti stabilizing the cubic phase and increasing its reduction enthalpy. A hydrogen yield of 10.0 ± 0.2 mL g−1 is achieved in a cycle between 1,350°C (reduction) and 1,150°C (water splitting) and a total cycle time of 1.5 h, exceeding all previous fuel production reports. The gas evolution rate suggests rapid material kinetics, and, at 1,150°C and higher, a process primarily limited by the magnitude of the thermodynamic driving force.
Original language | English (US) |
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Pages (from-to) | 688-708 |
Number of pages | 21 |
Journal | Matter |
Volume | 4 |
Issue number | 2 |
DOIs | |
State | Published - Feb 3 2021 |
Funding
This research is funded by the U.S. Department of Energy , through the office of Energy Efficiency and Renewable Energy (EERE) contract DE-EE0008089 . The support from the European Union’s Horizon 2020 Research And Innovation Programme under the Marie Sklodowska-Curie grant agreement no. 746167 is also acknowledged. This work made use of the Jerome B. Cohen X-Ray Diffraction Facility and the Pulsed Laser Deposition Shared Facility at the Materials Research Center at Northwestern University supported by the National Science Foundation MRSEC program ( DMR-1720139 ) and the Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource (NSF ECCS-1542205 ). This work additionally made use of the DuPont-Northwestern-Dow Collaborative Access Team (DND-CAT) located at Sector 5 of the Advanced Photon Source (APS) supported by Northwestern University , The Dow Chemical Company , and DuPont de Nemours, Inc . The APS is a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under contract no. DE-AC02-06CH11357 . The authors acknowledge Dr. Timothy Davenport and Dr. Stephen Wilke for help in thermochemical hydrogen production measurements, and graduate student Louis Wang for assistance with Rietveld refinements and for consultation on thermogravimetric measurements. This research is funded by the U.S. Department of Energy, through the office of Energy Efficiency and Renewable Energy (EERE) contract DE-EE0008089. The support from the European Union's Horizon 2020 Research And Innovation Programme under the Marie Sklodowska-Curie grant agreement no. 746167 is also acknowledged. This work made use of the Jerome B. Cohen X-Ray Diffraction Facility and the Pulsed Laser Deposition Shared Facility at the Materials Research Center at Northwestern University supported by the National Science Foundation MRSEC program (DMR-1720139) and the Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource (NSF ECCS-1542205). This work additionally made use of the DuPont-Northwestern-Dow Collaborative Access Team (DND-CAT) located at Sector 5 of the Advanced Photon Source (APS) supported by Northwestern University, The Dow Chemical Company, and DuPont de Nemours, Inc. The APS is a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under contract no. DE-AC02-06CH11357. The authors acknowledge Dr. Timothy Davenport and Dr. Stephen Wilke for help in thermochemical hydrogen production measurements, and graduate student Louis Wang for assistance with Rietveld refinements and for consultation on thermogravimetric measurements. X.Q. performed the majority of the experiments and their analysis. J.H. and B.B performed atomistic calculations. E.M. assisted with thermal analysis and W.Y. assisted with XANES measurements. C.W. supervised atomistic computational studies. S.M.H. and C.W. designed the research plan, with S.M.H. providing overall guidance for the research work. X.Q. and S.M.H. wrote the manuscript with input from all authors. The authors declare no competing interests.
Keywords
- MAP3: Understanding
- inorganic perovskite
- oxygen non-stoichiometry
- phase transition
- solar fuel
- thermo-kinetic limit
- thermochemical hydrogen production
- thermodynamic properties
ASJC Scopus subject areas
- General Materials Science