Expediting CH₄ combustion process over Ni-Ce composite oxide catalysts via a modulator-assisted synthesis strategy

Aiming at controllably fabricating Ni-Ce composite oxide catalysts for low-concentration methane combustion, a modulator-aided solvothermal tactics was employed. This was driven by that formic acid and terephthalic acid (1,4-BDC) as modulators differed in nucleophilicity towards metal centers and steric hindrance, which could tune the nucleation and crystallization process for Ce-Ni-BDC precursors, manipulating the synergism between NiO and Ce_1-zNi_zO_2-δ sosoloid over the derived Ni-Ce composite oxides. Consequently, the dimensions of NiO and Ce_1-zNi_zO_2-δ particles over the tailor-made catalyst were lowered, and more oxygen vacancy defects and interfaces were established, accelerating the transport for mobile oxygen from Ce_1-zNi_zO_2-δ to surface nickel centers. The capacity for surface lattice oxygen to extract H atoms and O-vacancy to activate aerial O₂ were augmented; the desorption of water became easier and accessible NiO sites were enriched. These benefits helped the catalyst to fulfil a redox circulation in CH₄ combustion, thus giving enhanced activity, and desirable reusability, stability and moisture-resistance.