Solar thermochemical CO2splitting with doped perovskite LaCo0.7Zr0.3O3: thermodynamic performance and solar-to-fuel efficiency

The research of thermochemical CO<INF>2</INF>splitting based on perovskites is a promising approach to green energy development. Performance evaluation was performed towards the doped perovskite LaCo<INF>0.7</INF>Zr<INF>0.3</INF>O<INF>3</INF>(LCZ-73) based two-step thermochemical CO<INF>2</INF>splitting process thermodynamically based on the experimentally derived parameters for the first time. The impacts of vacuum pump and inert gas purge to reduce oxygen partial pressure and CO<INF>2</INF>heating on the performance parameter eta<INF>solar-to-fuel</INF>have been analyzed. The results showed that at theP<INF>O<INF>2</INF></INF>of 10-5bar, non-stoichiometric oxygen delta increased by more than 3 times as the reduction temperature varied from 1000 degrees C to 1300 degrees C, however, no significant deviation of delta was observed between 1300 degrees C and 1400 degrees C. The reaction enthalpy ranged from 60 to 130 kJ mol-1corresponding to delta= 0.05-0.40. Comparing the abovementioned two ways to reduce the oxygen partial pressure, the eta<INF>solar-to-fuel</INF>of 0.39% and 0.1% can be achieved with 75% and without heat recovery with the CO<INF>2</INF>flow rate of 40 sccm under experimental conditions, respectively. The energy cost for CO<INF>2</INF>heating during the thermodynamic process as then<INF>CO<INF>2</INF></INF>/n<INF>LCZ-73</INF>increases was obtained from the perspective of energy analysis. The ratio ofn<INF>CO<INF>2</INF></INF>/n<INF>LCZ-73</INF>at lower temperature required more demanding conditions for the aim of commercialization. Finally, the ability of perovskite to split CO<INF>2</INF>and thermochemical performance were tested under different CO<INF>2</INF>flow rates. The results showed that high CO<INF>2</INF>flow rate was conducive to the production of CO, but at the cost of low eta<INF>solar-to-fuel</INF>. The maximum solar-to-fuel efficiency of 1.36% was achieved experimentally at a CO<INF>2</INF>flow rate of 10 sccm in the oxidation step and 75% heat recovery.