Self-generated Ni nanoparticles/LaFeO3 heterogeneous oxygen carrier for robust CO2 utilization under a cyclic redox scheme

High reaction temperature and low impurity-tolerance of traditional oxides challenges the application of CO2 reduction via chemical looping. Here, we report a robust and stable cyclic redox scheme with a self-generated Ni nanoparticles/LaFeO3 heterogeneous structure to efficiently utilize CO2. At a low temperature of 800 celcius, the LaNi0.05Fe0.95O3_delta exhibited stable and superior performance: 98% CO selectivity during the half cycle of methane oxidation; 98.5% CO2 conversion in another cycle of CO2 reduction even with other oxidative impurities, which were maintained for 100 redox cycles. Through a combination of catalyst characterizations, the existence of exsolved Ni metal nanoparticles from the bulk lattice was confirmed on the perovskite surface. The CO productivity only decreased by 1.5% when feeding the gas mixture (O2/CO2 = 25 at%) over the LaNi0.05Fe0.95O3_delta sample for CO2 reduction, much better than that in pure LaFeO3. It was verified that exsolved metal Ni served as catalytically active sites for both methane conversion and the activation of C-O bonds during CO2 reduction via the density functional theory calculation. The stable performance tolerant to oxygen gas enables Ni-modified LaFeO3 to effectively reduce cheap CO2 with impure oxidative gases. The proposed cyclic redox scheme offers an economic pathway of utilizing directly carbon sources from air capture without energycosting purifications.

Automated summary

A cyclic redox scheme with self-generated Ni nanoparticles/LaFeO3 heterogeneous structure was reported for efficient CO2 utilization at a low temperature of 800 degrees Celsius. The modified LaFeO3 sample showed stable and superior performance with high CO selectivity and CO2 conversion rates, even in the presence of impurities, over 100 redox cycles. The exsolved Ni metal nanoparticles on the perovskite surface served as catalytically active sites for methane conversion and activation of C-O bonds during CO2 reduction.