Strain‐Driven In Situ Ni Exsolution on (Sr,Ca)(Ti,Ni)O ₃ (100) Facets Boosts Hydrogen Spillover and Selective CO ₂ ‐to‐C ₂₊ Photoreduction

Photocatalytic CO 2 reduction offers a sustainable route to value‐added chemicals, yet conventional systems suffer from limited efficiency and hydrocarbon selectivity due to the spatial mismatch between CO 2 adsorption and proton sources, delaying proton‐coupled electron transfer (PCET). Here, we construct a Ni/(Sr,Ca)(Ti,Ni)O 3 heterostructure (Ni/SCTNO) via molten salt exsolution and aluminothermic reduction. Ca 2+ doping introduces lattice strain, which drives the in situ exsolution of Ni nanoparticles on the (100) facet, while oxygen vacancies create a positive space charge layer. These effects synergistically form Schottky junctions that act as hydrogen spillover centers, enabling directional H* migration to CO 2 sites and spatiotemporally coordinating proton–electron transport. Under simulated sunlight, CH 4 , C 2 H 4 , and C 2 H 6 yields reach 41.89, 18.01, and 16.53 µmol·g − 1 ·h − 1 , respectively, with a total hydrocarbon selectivity of 55.03%, surpassing most reported perovskite‐based photocatalysts. This work presents an integrated strategy combining heterointerface engineering, strain regulation, and surface modification for efficient CO 2 ‐to‐multicarbon fuel conversion.