A new carbon intercalated compound of Dion-Jacobson phase HLaNb2O7

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 angstrom, compared to that of 27.6 angstrom for n-decoxyl-HLaNb2O7. IR and solid-state C-13 CP/MASNMRspectra indicated that oxyalkyl chains were removed and glucopyranose rings were introduced. After pyrolysis of the D-glucopyranose derivative at 300 degrees 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 angstrom. Raman and solid-state C-13 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.