Influence of aliovalent doping on the La2−xSrxNi1−yCuyO4 for catalytic dry reforming of methane

Abstract

Aliovalent A- and B-site co-doping of the Ruddlesden–Popper layered perovskite La2NiO4 is demonstrated as a rational strategy to tune redox properties and enhance catalytic performance in dry reforming of methane. Sr2+ substitution at the A-site of La1.6Sr0.4Ni1−yCuyO4 induces Ni2+ → Ni3+ oxidation and changes in the oxygen-deficient surface environment, enhancing surface basicity and CO2 chemisorption. Progressive Cu2+ incorporation at the B-site lowers the thermodynamic threshold for Ni reduction forming bimetallic NiCu alloy phases at substantially lower temperatures than the pure Ni exsolution. Among the catalysts, La1.6Sr0.4Ni0.7Cu0.3O4 exhibited superior performance with negligible coke deposition. In situ FTIR analysis, together with XPS results, suggested the formation of carbonate, CHx, CHxO, formate, and COOH surface intermediates, indicating the involvement of diverse surface species during DRM that may involve reactive surface oxygen species. This work establishes synergistic Sr/Cu co-doping of La2NiO4 as an effective, scalable approach for active, selective, and coke-resistant catalysts for syngas production via dry reforming of methane.