Solvent-free strategy of multimetallic oxide nanosheets production for dry reforming of methane

This work reports for the first time a solvent-free synthesis strategy for nickel-incorporated single-phase multimetallic oxide nanosheets (LCCN-CA) via the co-melting of citric acid with metal nitrates. The development of stable and efficient catalysts for Dry Reforming of Methane (DRM) is essential for converting methane (CH4) and carbon dioxide (CO2) into synthesis gas, which can be further processed into valuable fuels via Fischer-Tropsch synthesis. Notably, LCCN-CA exhibits exceptional stability and activity in DRM, maintaining CO2 and CH4 conversion rates of 96 % and 93 %, respectively, over 200 h at 850 °C without phase separation or significant Ni nanoparticle agglomeration (8.2 nm before the reaction to 9.5 nm after 200 h of DRM operation). Density Functional Theory (DFT) calculations reveal that La2O3 hinders both CO2 adsorption and dissociation due to weak physisorption (Er = 0.14 eV), while LCCO facilitates stronger chemisorption of CO2 (Er = -0.66 eV) to form CO32–. Furthermore, Ni supported on LCCO has a d-band center closer to the Fermi level (−1.38 eV vs. −1.49 eV for La2O3), enhancing electron donation and facilitating methane dehydrogenation. These electronic effects are critical for weakening C–H bonds during methane activation, leading to lower reaction energies and activation barriers compared to Ni/ La2O3. This facile synthesis method not only opens new avenues for preparing high-entropy material nanosheets but also holds promise for advancing sustainable energy conversion processes, addressing global challenges related to greenhouse gas emissions and energy resource scarcity.