A new carbon intercalated compound of Dion–Jacobson phase HLaNb2O7

Abstract

Carbon was successfully intercalated into the interlayer space of the Dion–Jacobson type layered perovskite HLaNb₂O₇ by pyrolysis of the precursor of a D-glucopyranose derivative of HLaNb₂O₇. Firstly, the D-glucopyranose derivative of HLaNb₂O₇ (D-glucopyranose-HLaNb₂O₇) was prepared by the grafting reaction between the n-decoxyl derivative of HLaNb₂O₇ and D-glucopyranose. The interlayer distance of D-glucopyranose-HLaNb₂O₇ was decreased to 15.4 Å, compared to that of 27.6 Å for n-decoxyl-HLaNb₂O₇. IR and solid-state ¹³C CP/MAS NMR spectra indicated that oxyalkyl chains were removed and glucopyranose rings were introduced. After pyrolysis of the D-glucopyranose derivative at 300 °C under flowing Ar, a novel intercalation compound of HLaNb₂O₇ with carbon (carbon-HLaNb₂O₇) was obtained. XRD pattern and HRTEM image both displayed the interlayer distance of about 12 Å. Raman and solid-state ¹³C CP/MAS NMR spectra revealed that the intercalated carbon was mainly polycyclic aromatic carbon. The UV-VIS-near-IR spectrum showed that the carbon-HLaNb₂O₇ appreciably absorbed light at wavelengths below 855 nm and the band gap energy was only about 0.65 eV, which was much smaller than those of HLaNb₂O₇ and its derivatives, indicating that the intercalation with carbon can effectively modify the band gaps of Dion–Jacobson type layered perovskites.