Integrated Capture and Electroreduction of Low-Concentration CO2 to CO Using Geopolymer|Graphene-Cobalt Phthalocyanine Composite

Abstract

Green electricity-driven electrocatalytic CO₂ reduction (e-CO₂RR) has emerged as a promising approach to upcycle CO₂ into valuable chemicals and fuels, paving the way for a carbon-neutral economy. The success of such a device relies on the development of cost-effective catalysts that can efficiently and selectively catalyze e-CO₂RR. In the present contribution, the high activity and selectivity of graphene-supported CoPc (graphene-CoPc) are demonstrated toward CO generation from e-CO₂RR by encapsulating graphene|CoPc into Perlite–Metakaolin-based geopolymer (geopolymer|graphene-CoPc). The high electric conductivity (3.52 ± 0.4 S m⁻¹) and CO₂ adsorption capability (0.16 mmol CO₂ g⁻¹) of the geopolymer matrix, obtained through the systematic investigation and optimization of synthetic conditions, facilitate the charge transfer and provide high local CO₂ concentration. Consequently, this significantly enhancing both turnover frequency (2.3 ± 0.3 s⁻¹) and Faradaic efficiency (93.7 ± 3.1%) of geopolymer|graphene-CoPc for CO production from the low-concentration CO₂ (≈40%) in simulated biogas atmosphere at a low η of 0.69 V as compared to the pristine graphene-CoPc (turnover frequency: 1.37 ± 0.1 s⁻¹ and Faradic efficiency: 46.3 ± 2.0%).