A lattice oxygen-free design for efficient and stable photothermal methane dry reforming

Photothermal dry reforming of methane, a promising approach to producing syngas, typically uses oxide materials and is mediated by lattice oxygen. However, it is limited by the balance of the oxygen-releasing/replenishing loop. Here, we present a methane activation pathway free of lattice oxygen on a N-Ni/NiCo@C catalyst. Direct involvement of reactive oxygen species (O*/OH*) released from CO₂ promotes effective CH₄ activation and eliminates coke deposition on oxophilic NiCo sites. Control experiments and density functional theory calculations show that forming a C-N-Ni structure is essential for improving catalytic performance. This is achieved by strengtheni ng the electronic interaction between the NiCo nanoparticles and the carbon layer, thereby boosting the elemental steps of CH₄ dehydrogenation and CH* oxidation and preventing metal oxidation. The optimal catalyst exhibits a high light-to-chemical energy efficiency of 52%, maintaining stability during 200 hours of continuous operation at a mild temperature of 540 °C. This work demonstrates that highly efficient and stable photothermal dry reforming of methane can be achieved by bypassing lattice oxygen.