Graphitic Carbon Nitride as a Platform for the Synthesis of Silver Nanoclusters

Abstract

Graphitic carbon nitride (CN) synthetized by the thermal polycondensation of melamine at 550 °C for 4 h was further exfoliated by heating at 500 °C for 3 h. Silver cations were adsorbed on the exfoliated graphitic carbon nitride (CNE) and then reduced by sodium borohydride forming silver nanoclusters (NCs) with a size of less than 1 nm. The NCs were located on the CNE surface and did not change the CNE properties except for its pore size distribution and thereby specific surface area (SSA). The Ag NCs were able to collect the photoinduced electrons of CNE and thus reduce their recombination with the holes. It was also documented by the increase in the CNE photocatalytic activity in terms of the degradation of antibiotic Ofloxacin. This study demonstrates the ability of CNE to serve as a platform for a simple and fast synthesis of Ag NCs without any stabilizing compounds.

Keywords: Graphitic carbon nitride; Ofloxacin; Photocatalysis; Silver nanoclusters; Synthesis.

Fig. 1

TEM micrographs of AgCNE4 with different resolutions

Fig. 2

STEM micrographs of AgCNE4 (left) and its detail view (right)

Fig. 3

HAADF-STEM micrographs and EDS spectrum (down) of AgCNE4

Fig. 4

XRD patterns of AgCNE nanomaterials

Fig. 5

FTIR spectra of AgCNE nanomaterials

Fig. 6

XPS spectra of Ag 3d of Ag⁺ adsorbed on CNE (left) and AgCNE4 (right)

Fig. 7

XPS spectra of Auger line Ag MNN of Ag⁺CNE2 (left) and AgCNE4 (right)

Fig. 8

Nitrogen adsorption–desorption isotherms of AgCNE nanomaterials

Fig. 9

BJH pore size distribution curves of AgCNE nanomaterials

Fig. 10

SEM micrographs of CNE (left) and AgCNE4 (right)

Fig. 11

UV–Vis spectra of AgCNE nanomaterials

Fig. 12

Photoluminescence spectra of AgCNE nanomaterials. Left—(1) CNE, (2) AgCNE1, (3) AgCNE2, (4) AgCNE3, (5) AgCNE4. Right—CNE, Ag⁺CNE2 and AgCNE2

Fig. 13

Photocatalytic degradation of Ofloxacin. LED source of 420 nm and 7.1 mW cm−2; the temperature was kept at 20 °C