Synergistic Tuning of Oxygen Vacancies, Basic Sites, and Metal−Support Interaction in NiAlCeLa LDH-Derived Catalyst for Low-Temperature CO2 Methanation

Abstract Developing Ni-based catalysts for low-temperature CO2 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 (OV), weak and medium basic sites (WBS/MBS), and metal−support interaction (MSI) govern the catalytic activity of the catalysts. Incorporation of Ce into Ni2Al-LDH generates abundant OV, while subsequent La introduction into Ni2AlCe0.4La0.05-LDH provides additional structural and electronic benefits. Upon calcination, insertion of La into the ceria lattice of Ni2AlCe0.4La0.05 further amplifies OV formation, enriches WBS/MBS, and enhances NiO reducibility and interfacial Ni electron density. Owing to these synergistic effects, Ni2AlCe0.4La0.05 provides 85% CO2 conversion, a CH4 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 OV in Ni2AlCe0.4La0.05 facilitate CO2 activation into HCO3 and b-CO3 species, which are easily hydrogenated to CH4 via the formate pathway. This work establishes a rational catalyst design strategy to integrate OV formation, surface basicity modulation, and MSI tuning for low-temperature CO2 methanation.