Iron-triggered exsolution of FeNi alloy nanoparticles via topotactic cation exchange on Pr0.7Sr0.3Cr0.9Ni0.1O3−δ perovskite for CO2 electrolysis

Perovskites with in situ exsolved metal nanoparticles have been extensively studied for CO2 electrolysis in solid oxide electrolysis cell. However, exsolution process is strongly governed by the sluggish diffusion rate of cations and poor structural stability issues. Here we present a new exsolution process on redox stable Pr0.7Sr0.3Cr0.9Ni0.1O3−δ (PSCN) perovskite by topotactic exsolution. This process tends to generate host stoichiometric Pr0.7Sr0.3Cr0.9(FeNi)0.1O3−δ perovskite, triggering Ni cations segregation from the host while maintaining structural stability via supplement of Fe guest cations. The FeNi alloy nanoparticles decorated cathode showed a current density of 1.49 A cm−2 at 800 °C and 1.6 V for CO2 electrolysis, demonstrating over 62.0 % improvement compared to the primitive PSCN cathode. Experimental studies and density functional theory calculations revealed that the activity originated from the unique ability to adsorb and activate CO2 at the metal/perovskite interfaces. This cation supplement strategy may expand the frontiers in the evolution of exsolution on perovskite catalysts for CO2 utilization and other heterogeneous catalytic reactions. [Display omitted] •Stable FeNi@PSCN cathode is constructed via topotactic cation exchange for CO2 electrolysis in solid oxide electrolysis cells.•The deposition of Fe guests cations trigger the exsolution of FeNi alloy nanoparticles via Fe cations substitution.•Fe cations supplement effectively restrains the structural collapse of the perovskite during exsolution.•Topotactic exsolved FeNi@PSCN cathode greatly promoted the CO2 electrolysis performance.