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. The pore size, basicity, and binding energy of triazole‐based C3N5 nanorods were tailored to investigate the effects of the parameters on CO2 capture and conversion using a single material of carbon nitride. Its large basicity and strong binding energy are beneficial for the adsorption of large amounts of CO2, whereas the wide pore size is good for mass transport in electrocatalytic CO2 conversion.