Carbon diffusion mechanism as an effective stability enhancement strategy: The case study of Ni-based catalyst for photothermal catalytic dry reforming of methane

Photothermal catalytic methane dry reforming (DRM) technology can convert greenhouse gases (i.e. CH4 and CO2) into syngas (i.e. H2 and CO), providing more opportunities for reducing the greenhouse effect and achieving carbon neutrality. In the DRM field, Ni-based catalysts attract wide attention due to their low cost and high activity. However, the carbon deposition over Ni-based catalysts always leads to rapid deactivation, which is still a main challenge. To improve the long-term stability of Ni-based catalysts, this work proposes a carbon-atom-diffusion strategy under photothermal conditions and investigates its effect on a Zn-doped Ni-based photothermal catalyst (Ni3Zn@CeO2). The photothermal catalytic behavior of Ni3Zn@CeO2 can maintain more than 70 h in DRM reaction. And the photocatalytic DRM activity of Ni3Zn@CeO2 is 1.2 times higher than thermal catalytic activity. Density functional theory (DFT) calculation and experimental characterizations indicate that Ni3Zn promotes the diffusion of carbon atoms into the Ni3Zn to form the Ni3ZnC0.7 phase with body-centered cubic (bcc) structure, thus inhibiting carbon deposition. Further, in-situ diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy and DFT calculation prove Ni3Zn@CeO2 benefits the CH4 activation and inhibits the carbon deposition during the DRM process. Through inducing carbon atoms diffusion within the Ni3Zn lattice, this work provides a straightforward and feasible strategy for achieving efficient photothermal catalytic DRM and even other CH4 conversion implementations with long-term stability. Published by Elsevier B.V. All rights reserved.