Contribution of polytetrafluoroethylene to the atmosphere-dependent synthesis of Cu-based nanomaterials through ion–dipole interactions

Abstract

A simple, but efficient, method for the preparation of a series of Cu-based nanomaterials including Cu, CuCl, CuO, Cu@CuCl and CuCl@CuO was developed. Initially, we prepared a novel precursor consisting of a Cu(II)-urea complex (CUC, a coordination compound) and polytetrafluoroethylene (PTFE, a waterinsoluble polymer) using the technique of solid-solid grinding. Subsequently, the Cu-based materials were synthesized by sintering the precursor at different atmospheres and temperatures. This approach provides an environmentally friendly and green alternative towards creating Cu-based materials by generating complex-polymer binary systems without the use of solvents. Our results indicated that the effect of PTFE played a crucial role in the formation of the materials. Further, the role of PTFE was found to be associated with sintering atmospheres: the reduction of CuCl to Cu in nitrogen was delayed;contrarily its oxidation to CuO in air was advanced. The nature of this role was ascribed to an ion-dipole interaction between the partial negative charges on the fluorine atoms (F dÀ ) on the PTFE chains and the Cu(II) ions in the coordination centers [Cu(II)-urea] induced by a solid-solid mixing process, leading to the CUC complex decomposing later in nitrogen and earlier in air. Also, the presence of CUC drastically affects the thermal pyrolysis pattern of PTFE, resulting in a remarkable decrease, and even disappearance of the etching signals of PTFE. Finally, our data suggested that the as-prepared Cu@CuCl nanomaterial induced a strong surface-enhanced Raman scattering effect for several model compounds, including rhodamine 6G and crystal violet. We believe that this study represents a significant step towards the development of practical synthesis of Cu-based nanomaterials and opens up exciting opportunities for the design and construction of a wide range of transition metal-based nanomaterials through the link between polymers and coordination compounds.

Modulation of Exposed Active Sites and Electronic Structure of Co-Doped Carbon Nitride Achieving Enhanced Activity toward Peroxymonosulfate Activation for Antibiotic Degradation

“…First, CoSO 4 and urea are dissolved in the mixed solvent of water and ethanol. After the complete evaporation of the solvent under stirring, the Co 2+ -urea complex is formed during this recrystallization process, , which ensures the homogeneous distribution of Co 2+ ions in the precursor. When NH 4 Cl is added, it acts as a gaseous templating agent and releases NH 3 and HCl during the polymerization of urea to CN.…”

“…The atomic percentages of Co and Cl calculated according to XPS spectra are 0.12% and 0.19%, respectively. The high-resolution C 1s spectrum (Figure a) can be deconvoluted into two peaks at 284.3 and 287.8 eV, which are attributed to the graphitic carbon (C–C/CC) and sp 2 hybridized carbon (N–CN) in the aromatic ring, respectively . For the N 1s spectrum shown in Figure b, the three peaks at 398.2, 399.7, and 400.6 eV are attributed to the sp 2 hybridized nitrogen (CN–C), the tertiary nitrogen moiety (N–C 3 ), and the amino group (C–NH x ), , respectively.…”

“…The HRTEM image and the corresponding elemental mapping images of CoCN-6NH 4 Cl (Figure 3d-h) reveal that the elements C, N, Co, and Cl are uniformly distributed in the catalyst. 32 For the N 1s spectrum shown in Figure 5b, the three peaks at 398.2, 399.7, and 400.6 eV are attributed to the sp 2 hybridized nitrogen (C�N−C), the tertiary nitrogen moiety (N−C 3 ), and the amino group (C−NH x ), 31,41 respectively. The presence of Co and Cl in the sample can be identified by high-resolution Co 2p and Cl 2p XPS spectra.…”