NiCo Alloy Catalysts for Low-Temperature Solar-Driven Methane Dry Reforming: Insights into CH₄ Activation and Carbon Accumulation

Solar-driven dry reforming of methane (DRM) offers a milder, more cost-effective, and promising environmentally friendly pathway compared to traditional thermal catalytic DRM. Numerous studies have extensively investigated inexpensive Ni-based catalysts for application in solar-driven DRM. However, these catalysts often suffer from activity loss due to carbon accumulation. In this study, we enhanced the Ni-based catalyst by introducing a secondary cobalt active component. The Al 2 O 3 supporting NiCo alloy catalyst (NiCo/Al 2 O 3 ), synthesized from layered double hydroxides (LDH), exhibits superior light-absorbing properties. This catalyst demonstrates enhanced resistance to carbon accumulation and greater stability compared to Ni monometallic catalysts in solar-driven DRM. Under the extremely demanding conditions of low light irradiation intensity (1.34 W·cm –2 ), the yields of H 2 and CO from the Ni 2 Co 1 /Al 2 O 3 catalysts in DRM were 596.6 and 499.1 μmol·g –1 ·h –1, respectively. In addition, in the light-assisted thermal-driven catalytic DRM test, the H 2 and CO yields of Ni 2 Co 1 /Al 2 O 3 catalysts increased by 44.5% and 29.2%, respectively, with the application of only 0.28 W·cm –2 of light irradiation during heating at 350 °C. In situ infrared spectroscopy revealed that the reaction pathways of solar-driven DRM closely resemble those of thermally catalytic DRM, suggesting that the NiCo/Al 2 O 3 absorbed light and converted it into heat and drived the DRM reaction. Furthermore, the in situ infrared spectroscopy tests showed that light irradiation could suppress the reverse water–gas shift reaction. The photothermal catalysts developed in this work provide a green industrial route to the production of DRM.