Preparation and photoelectric properties of nitrogen-doped graphene quantum dots modified SnO2 composites

Co,N-doped GQDs/SnO2 mesoporous microspheres exhibit synergistically enhanced gas sensing properties for H2S gas detection

“…4d) is divided into three contributions at 530.4, 531.6 and 532.4 eV, which are attributed to C–O–C/C–OH and CO, respectively. 42 The high-resolution XPS spectrum of N 1s (Fig. 4e) presents two contributions at 401.71 and 400.06 eV, belonging to C–N–C and N–H, respectively.…”

“…4c) has four contributions, including CC (284.47 eV), C–C (284.97 eV), C–O/C–N (286.13 eV), and CO (288.81 eV). 42 The high-resolution XPS spectrum of O 1s (Fig. 4d) is divided into three contributions at 530.4, 531.6 and 532.4 eV, which are attributed to C–O–C/C–OH and CO, respectively.…”

“…3a, the XRD spectra of SnO 2 , Co,N-GQDs/SnO 2 and N-GQDs/SnO 2 nanocomposites have the same peaks at the Bragg intersection (2q) corresponding to the (110), (101), ( 211) and (112) planes of the tetragonal rutile SnO 2 structure (JCPDS le card number 41-1445), consistent with the SAED results; moreover, it is found that there are no diffraction peaks of GQDs in the XRD patterns, and all the diffraction peaks can be attributed to the diffraction peaks of pure SnO 2 , further conrming that the GQDs did not change the SnO 2 crystalline structure, which conformed with the results of HRTEM and SAED and previously reported results. 41,42 This phenomenon is attributed to the low content and relatively low diffraction intensity of GQDs. 32 The structures and functional groups of Co,N-GQDs are continuously characterized by Fourier transform infrared spectroscopy (FTIR).…”

“…3b, due to the O-H vibration of H 2 O in air, the sample exhibits a broad absorption peak at 3410 cm À1 and a weak absorption peak at 1307 cm À1 . 42,43 The strong absorption peak at a high wavenumber 3232 cm À1 is related to the characteristic stretching vibration of N-H. 37 The absorption peak at 1571 cm À1 is connected with the stretching vibration of the C]C bond, which is caused by the skeleton vibration of the graphene sheet. 44 The absorption peaks at 1705 This journal is © The Royal Society of Chemistry 2022 and 1408 cm À1 are relevant to the stretching vibrations of C]O and C-N bonds, respectively.…”

“…44 The absorption peaks at 1705 This journal is © The Royal Society of Chemistry 2022 and 1408 cm À1 are relevant to the stretching vibrations of C]O and C-N bonds, respectively. 37,42 The two absorption peaks at 1190 and 1069 cm À1 are attributed to the stretching vibration of C-O (carboxyl group) and C-O (alkoxy group), respectively. 28 All these results indicate the existence of multiple oxygen-containing and nitrous acid functional groups in Co,N-GQDs.…”