Graphite–Ni synergy unlocks a hydrogen-free pathway for carbon based integrated CO₂ capture and utilisation (ICCU)

• A carbon-based ICCU (C-ICCU) pathway is proposed to avoid hydrogen dependence. • Ni/graphite composites catalyze in-situ CO₂ conversion via the reverse Boudouard reaction. • CaCO₃ decomposition coupled with Ni/graphite achieves >95% CO₂ conversion at 600–650°C. • Optimal Ni loading is 3–5 wt.%, with no further improvement at higher loadings. • In-situ DRIFTS reveals synergistic graphite-assisted CO₂ release and Ni-catalyzed CO formation. Integrated carbon capture and utilisation (ICCU) is a promising technology to mitigate the impact of carbon emissions, as it combines sorbent regeneration and CO 2 utilisation. ICCU has been intensively studied for reverse water shift reaction (RWGS), methanation and dry methane reforming (DRM). However, ICCU-RWGS and ICCU-Methanation rely on hydrogen, which compromises economic viability and safety, and the complex synthesis of DFMs for ICCU-DRM, requiring promoters or multilayer structures. To enhance the practicality of ICCU technology, here we investigated carbon-based ICCU (C-ICCU), which utilises the reverse Boudouard reaction with carbon as the reducing agent. In this study, we explored the key operational factors influencing C-ICCU performance, specifically Ni loading, the Ni/graphite mass, and temperature. Our findings indicate that Ni/graphite is a highly effective catalyst for the in-situ conversion of CO 2 to CO. Specifically, a Ni loading of 3 wt.% or higher achieved a CO 2 conversion greater than 95% at 650°C. Furthermore, in-situ Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) analysis revealed the synergistic interactions between graphite and nickel. Specifically, graphite promotes CO 2 generation while nickel catalyses its subsequent conversion. Our research demonstrates that the C-ICCU mechanism is a complex synergistic process involving the dynamic evolution of surface species. This work offers a promising, safer, and potentially more economical pathway for industrial carbon capture and utilisation.