A new dry reforming of methane catalyst comprised of NiCo bimetallic nanoparticles and a Mg x (Al)O support that exhibits high coke resistance and long-term on-stream stability is reported. The structural characterization by XRD, TEM, temperature-programmed reduction, and BET analysis demonstrates that the excellent performance of this catalyst is ascribed to the synergy of various parameters, including metal-nanoparticle size, metal-support interaction, catalyst structure, ensemble size, and alloy effects.Dry reforming of methane (DRM) uses CH 4 and CO 2 (greenhouse gases) as reactants to produce H 2 and CO (syngas), the latter is an important industrial intermediate to yield other valuable chemicals and fuels, such as ammonia, methanol, dimethyl ether, and synfuel. [1] This reaction is highly endothermic and is commonly performed at high temperature (700-950 8C), under which the nickel-based DRM catalyst rapidly becomes deactivated because of sintering, oxidation, or coke formation. Compared to steam reforming of methane (SRM), DRM causes more-severe coke formation because of the increased C/H molar ratio in the feedstock. Therefore, development of a coke-resistant nickel-based catalyst constitutes the major challenge for the DRM.The DRM catalyst is commonly comprised of metal nanoparticle and oxide support. The former is assumed to be responsible for CH 4 dissociation by several elementary steps, leading ultimately to carbon and hydrogen. The metal nanoparticle may also have an impact on nucleation and growth of carbon, which possibly leads to "graphite-like materials" and causes the deactivation of catalyst. [2] The oxide support is supposedly involved in CO 2 adsorption and dissociation, in which CO 2 is activated by the reaction with the support to yield carbonate species (e.g., Pt/ZrO 2 [3] ) and then reacts with the C* or other CH x * species on the interface of metal nanoparticle and support. This reaction is recognized as a process of gasification of carbon. CO 2 may also react directly with carbon on the metal surface to generate CO through an Eley-Rideal-type mechanism (as demonstrated in the case of Rh catalyst [4] ). An ideal coke-free DRM catalyst has to contain the elements that will prevent the nucleation and growth of carbon on the metal surface and meanwhile enhance the gasification of carbon. It has been revealed that many factors, for example, metal-nanoparticle size, [5] ensemble size, [6] nature of metal, [7] acidity/basicity of support, [8] metal-support interaction, [9] and surface composition and structure of metal nanoparticle, [10] may play roles in the suppression of coke formation through directly or indirectly influencing nucleation and growth of carbon or gasification of carbon.However, a large number of experimental results have demonstrated that it is hard to achieve an ideal coke-resistant and thermally stable DRM catalyst by exclusively adjusting one single parameter. [11] For instance, we recently synthesized two silica-and alumina-supported nickel catalysts with very s...