Tailoring the Pore Size, Basicity, and Binding Energy of Mesoporous C₃N₅ for CO₂ Capture and Conversion

We investigated the CO₂ adsorption and electrochemical conversion behavior of triazole-based C₃N₅ nanorods as a single matrix for consecutive CO₂ capture and conversion. The pore size, basicity, and binding energy were tailored to identify critical factors for consecutive CO₂ capture and conversion over carbon nitrides. Temperature-programmed desorption (TPD) analysis of CO₂ demonstrates that triazole-based C₃N₅ shows higher basicity and stronger CO₂ binding energy than g-C₃N₄. Triazole-based C₃N₅ nanorods with 6.1 nm mesopore channels exhibit better CO₂ adsorption than nanorods with 3.5 and 5.4 nm mesopore channels. C₃N₅ nanorods with wider mesopore channels are effective in increasing the current density as an electrocatalyst during the CO₂ reduction reaction. Triazole-based C₃N₅ nanorods with tailored pore sizes exhibit CO₂ adsorption abilities of 5.6–9.1 mmol/g at 0 °C and 30 bar. Their Faraday efficiencies for reducing CO₂ to CO are 14–38% at a potential of −0.8 V vs. RHE.