Symmetrical distribution of P sites on thorn assembled Graphite carbon nitride microtube for photocatalytic conversion of CO2

Photocatalytic conversion of CO2 to form value-added fuels is a promising strategy to simultaneously mitigate climate changes and achieve carbon neutral. Graphite carbon nitride (g-C3N4) is one of the potential candidates for photocatalytic CO2 reduction, but limited by its low specifical surface area and absence of active sites. Here, we design a thorn grown tubular g-C3N4 (ThCN) with P sites by pyrolysis of supramolecular precursors prepared from melamine and hexachlorocyclo-triphosphonitrile (HCCP). ThCN offers an extraordinary photocatalytic activity in CO2 conversion with a yield of 442.2 μmol g−1 (170.1 μmol g−1 for CH4 and 272.1 μmol g−1 for CO) under AM 1.5G irradiation. The technique of in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) enables the identification of a series of key intermediates involved in the production of CO and CH4 with high activity. Density functional theory (DFT) calculations reveal that ThCN with rich N-P-N sites reduce barrier energy from CO2 to COOH* and CHO* intermediate, which is beneficial to subsequent reduction process to produce CO and CH4. This work provides a significant insight into regulating molecule structure and morphology of g-C3N4 photocatalysts to promote the CO2 conversion process.