g-C₃N₄-Mediated Synthesis of Cu₂O To Obtain Porous Composites with Improved Visible Light Photocatalytic Degradation of Organic Dyes

Abstract

A highly porous architecture of graphitic carbon nitride g-C3N4/Cu2O nanocomposite in the form of cubes with a side length of ≈ 1 μm, large pores of 1.5 nm, and a high surface area of 9.12 m2/g was realized by an optimized in situ synthesis protocol. The synthesis protocol involves dispersing a suitable “Cu” precursor into a highly exfoliated g-C3N4 suspension and initiating the reaction for the formation of Cu2O. Systematic optimization of the conditions and compositions resulted in a highly crystalline g-C3N4/Cu2O composite. In the absence of g-C3N4, the Cu2O particles assemble into cubes with a size of around 300 nm and are devoid of pores. Detailed structural and morphological evaluations by powder X-ray diffraction and field emission scanning electron microscopy revealed the presence of highly exfoliated g-C3N4, which is responsible for the formation of the porous architecture in the cube like assembly of the composite. The micrographs clearly reveal the porous structure of the composite that retains the cubic shape of Cu2O, and the energy-dispersive spectroscopy supports the presence of g-C3N4 within the cubic morphology. Among the different g-C3N4/Cu2O compositions, CN/Cu-5 with 10% of g-C3N4, which is also the optimum composition resulting in a porous cubic morphology, shows the best visible light photocatalytic performance. This has been supported by the ultraviolet diffuse reflectance spectroscopy (UV-DRS) studies of the composite which shows a band gap of around 2.05 eV. The improved photocatalytic performance of the composite could be attributed to the highly porous morphology along with the suitable optical band gap in the visible region of the solar spectrum. The optimized composite, CN/Cu-5, demonstrates a visible light degradation of 81% for Methylene Blue (MB) and 85.3% for Rhodamine-B (RhB) in 120 min. The decrease in the catalyst performance even after three repeated cycles is less than 5% for both MB and RhB dyes. The rate constant for MB and RhB degradation is six and eight times higher with CN/Cu-5 when compared with the pure Cu2O catalyst. To validate our claim that the dye degradation is not merely decolorization, liquid chromatography–mass spectroscopy studies were carried out, and the end products of the degraded dyes were identified.

A highly sensitive uric acid electrochemical biosensor based on a nano-cube cuprous oxide/ferrocene/uricase modified glassy carbon electrode

“…XRD spectra of Cu 2 O NPs showed the diffraction peaks appeared at a 2θ value of 29.48°, 36.38°, 42.20°, 61.32°, 75.26° and 76.30° corresponds to the (110), (111), (200), (220), (311) and (222) characteristic planes, and confirmed that all the diffraction peaks in the XRD spectrum correspond to the standard pattern of cuprous oxide cubic crystal system (PDF#05-0667, cell parameter a = 0.4269 nm) ( Fig. S1), and had high diffraction intensity and sharp peak shape, indicating that the products had good crystallinity 25,26 . It can also be seen from the XRD spectra that the synthesized nanoparticles had no impurity peak, indicating that the product had a single crystal shape and high crystal purity ( Fig.…”

Investigation on Cu2O Combined g-C3N4/ZnO Heterostructures For High-Performance Photocatalytic Dye Degradation Under Visible-Light Exposure

“…No substantial changes were noticed in the structures and active functional groups of the photocatalyst before and after reused, which speci es that the g-C 3 N 4 /ZnO/Cu 2 O heterostructured photocatalyst was greatly stable. The as-obtained photocatalytic activity of this work was better for with the formerly reported photo-degradation [38,[45][46][47]. Also, the photocatalytic performance of g-C 3 N 4 /ZnO/Cu 2 O composite photocatalyst was greater when compared to the commercial P25 TiO 2 NPs [48].…”

“…Based on the photo-degradation outcomes, a possible charge transfer mechanism of g-C ), and then ˙O 2 − radicals and h + are capable to openly oxidize the organic impurities (RhB dye) owing to their great oxidative ability reagents for RhB [45] dye to make it degrade eventually. Thus the synergistic separation of photo-excited e − /h + pairs could be captured on the g-C 3 N 4 surface of the PCs to yield a variety of reactive oxygen species (ROSs) to effect the desired degradation in the aqueous dye solution [58].…”

Ag-Modified g-C3N4 Prepared by a One-Step Calcination Method for Enhanced Catalytic Efficiency and Stability

“…In Figure 5 b, the high-resolution spectra of C 1s could be fitted into three peaks at about 283.2, 284.7, and 288.2 eV in Ag/CN-8, which were assigned to the aromatic carbon atom, the C–C coordination, and the N=C—N coordination, respectively. 36 − 39 Figure 5 c shows that the N 1s spectra could also be separated into two peaks centered at 398.7 and 400.3 eV in Ag/CN-8, which were ascribed to C—N=C, N–(C) 3 , and N–H, respectively. 40 − 42 Compared with CN-1, the C 1s and N 1s peak of Ag/CN-8 shifted to a higher binding energy, which could be assigned to the interaction between Ag and g-C 3 N 4 .…”