Perovskites with exsolved nanoparticles (P-eNs) have immense potentials for carbon dioxide (CO2) reduction in solid oxide electrolysis cell. Despite the recent achievements in promoting the B-site cation exsolution for enhanced catalytic activities, the unsatisfactory stability of P-eNs at high voltages greatly impedes their practical applications and this issue has not been elucidated. In this study, we reveal that the formation of B-site vacancies in perovskite scaffold is the major contributor to the degradation of P-eNs; we then address this issue by fine-regulating the B-site supplement of the reduced Sr2Fe1.3Ni0.2Mo0.5O6-δ using foreign Fe sources, achieving a robust perovskite scaffold and prolonged stability performance. Furthermore, the degradation mechanism from the perspective of structure stability of perovskite has also been proposed to understand the origins of performance deterioration. The B-site supplement endows P-eNs with the capability to become appealing electrocatalysts for CO2 reduction and more broadly, for other energy storage and conversion systems.

The in situ exsolution technique of nanoparticles has brought new opportunities for the utilization of perovskite-based catalysts in solid oxide cells. However, the lack of control over the structural evolution of host perovskites during the promotion of exsolution has restricted the architectural exploitation of exsolution-facilitated perovskites. In this study, we strategically broke the long-standing trade-off phenomenon between promoted exsolution and suppressed phase transition via B-site supplement, thus broadening the scope of exsolution-facilitated perovskite materials. Using carbon dioxide electrolysis as an illustrative case study, we demonstrate that the catalytic activity and stability of perovskites with exsolved nanoparticles (P-eNs) can be selectively enhanced by regulating the explicit phase of host perovskites, accentuating the critical role of the architectures of perovskite scaffold in catalytic reactions occurring on P-eNs. The concept demonstrated could potentially pave the way for designing the advanced exsolutionfacilitated P-eNs materials and unveiling a wide range of catalytic chemistry taking place on P-eNs.

The in situ exsolution technique of nanoparticles has brought new opportunities for the utilization of perovskite‐based catalysts in solid oxide cells. However, the lack of control over the structural evolution of host perovskites during the promotion of exsolution has restricted the architectural exploitation of exsolution‐facilitated perovskites. In this study, we strategically broke the long‐standing trade‐off phenomenon between promoted exsolution and suppressed phase transition via B‐site supplement, thus broadening the scope of exsolution‐facilitated perovskite materials. Using carbon dioxide electrolysis as an illustrative case study, we demonstrate that the catalytic activity and stability of perovskites with exsolved nanoparticles (P‐eNs) can be selectively enhanced by regulating the explicit phase of host perovskites, accentuating the critical role of the architectures of perovskite scaffold in catalytic reactions occurring on P‐eNs. The concept demonstrated could potentially pave the way for designing the advanced exsolution‐facilitated P‐eNs materials and unveiling a wide range of catalytic chemistry taking place on P‐eNs.

Controlling the chemical environment of the atomically dispersed central atoms doped in the graphene lattice is critical to achieve desirable catalytic performances in carbon dioxide reduction reaction (CO2RR), however, how the local structures of non-transition metal-based single atom (SAs) affect the catalytic performances of CO2RR remains less understood. This study reports the immobilization of bismuth single atom catalysts (SACs) on pristine and nitrogenated graphene nanosheets with switchable catalytic selectivity in the carbon dioxide reduction reaction (CO2RR). Based on systematic physical characterizations and electrochemical analysis, it has been demonstrated that the Bi atom coordinated with four adjacent nitrogen atoms (Bi-N-C) selectively produces carbon monoxide (CO) with high selectivity at low overpotential, whereas Bi SACs bounded with carbon atoms (Bi-C) almost exclusively generate formate (FA). Theoretical investigations reveal that the Bi-N-C catalyst displays the lowest activation barrier for the first hydrogenation step of CO2 to produce *COOH, while Bi-C shows the most preferable pathway towards the formation of *OCHO, which is considered as the important intermediate species to generate FA. The controllable product distributions are dictated by the different local structures of Bi centers in Bi-N-C and Bi-C, and such differences could induce distinct electronic properties of Bi centers and subsequently switch the CO2RR products from CO to FA. This work has substantiated the importance of the fine-regulation of the coordination environment of one of the representative p-blocking SAs to steer the selectivity of CO2RR.