Synergistic Tuning of Oxygen Vacancies, Basic Sites, and Metal−Support Interaction in NiAlCeLa LDH-Derived Catalyst for Low-Temperature CO ₂ Methanation

Developing Ni-based catalysts for low-temperature CO 2 methanation remains challenging due to the kinetic limitation. Layered double hydroxides (LDHs) have emerged as versatile catalyst precursors enabling structural tunability through cation incorporation. Here, we report a stepwise catalyst design strategy implemented at the LDH stage, in which Ce and La are simultaneously incorporated into NiAl-LDH to engineer structural defects and catalytic functionality. A series of NiAl-LDH, NiAlCe-LDH, and NiAlCeLa-LDH materials was synthesized via a one-pot hydrothermal method with designated metal ratios (Ni/Al= 1−5, Ce/Al = 0.2−1.0, and La/Ce = 0.025−1.0). Systematic characterization reveals that oxygen vacancies (O V ), weak and medium basic sites (WBS/MBS), and metal−support interaction (MSI) govern the catalytic activity of the catalysts. Incorporation of Ce into Ni 2 Al-LDH generates abundant O V, while subsequent La introduction into Ni 2 AlCe 0.4 La 0.05 -LDH provides additional structural and electronic benefits. Upon calcination, insertion of La into the ceria lattice of Ni 2 AlCe 0.4 La 0.05 further amplifies O V formation, enriches WBS/MBS, and enhances NiO reducibility and interfacial Ni electron density. Owing to these synergistic effects, Ni 2 AlCe 0.4 La 0.05 provides 85% CO 2 conversion, a CH 4 production rate of 69.5 mmol g −1 h −1, and a TOF of 0.35 s −1 at 180 °C. In situ DRIFTS analysis reveals that OH groups and O V in Ni 2 AlCe 0.4 La 0.05 facilitate CO 2 activation into HCO 3 and b-CO 3 species, which are easily hydrogenated to CH 4 via the formate pathway. This work establishes a rational catalyst design strategy to integrate O V formation, surface basicity modulation, and MSI tuning for low-temperature CO 2 methanation.