Surface functionalization of metallic and semiconducting 2D transition metal dichalcogenides (TMDs) have mostly relied on physi- and chemi-sorption at defect sites, which can diminish the potential applications of the decorated 2D materials, as structural defects can have substantial drawbacks on the electronic and optoelectronic characteristics. Here, we demonstrate a spontaneous defect-free functionalization method consisting of attaching Au single atoms to monolayers of semiconducting MoS2(1H) via S-Au-Cl coordination complexes. This strategy offers an effective and controllable approach for tuning the Fermi level and excitation spectra of MoS2 via p-type doping and enhancing the thermal boundary conductance of monolayer MoS2, thus promoting heat dissipation. The coordination-based method offers an effective and damage-free route of functionalizing TMDs and can be applied to other metals and used in single-atom catalysis, quantum information devices, optoelectronics, and enhanced sensing.

Graphene oxide (GO) with their interesting properties including thermal and electrical conductivity and antibacterial characteristics have many promising applications in medicine. The prevalence of resistant bacteria is considered a public health problem worldwide, herein, GO has been used as a broad spectrum selective antibacterial agent based on the photothermal therapy (PTT)/photodynamic therapy (PDT) effect. The preparation, characterization, determination of photophysical properties of two different sizes of GO is described. In vitro light dose and concentration-dependent studies were performed using Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus bacteria based on the PTT/PDT effect used ultra-low doses (65 mW cm −2 ) of 630 nm light, to achieve efficient bacterial decontamination. The results show that GO and nanographene oxide (nGO) can sensitize the formation of 1 O 2 and allow a temperature rise of 55 • C to 60 • C together nGO and GO to exert combined PTT/PDT effect in the disinfection of gram-positive S. aureus and gram-negative E. coli bacteria. A complete elimination of S. aureus and E. coli bacteria based on GO and nGO is obtained by using a dose of 43-47 J cm −2 for high concentration used in this study, and a dose of around 70 J cm −2 for low dose of GO and nGO. The presence of high concentrations of GO allows the bacterial population of S. aureus and E. coli to be more sensitive to the use of PDT/PTT and the efficiency of S. aureus and E. coli bacteria disinfection in the presence of GO is similar to that of nGO. In human neonatal dermal fibroblast, HDFs, no significant alteration to cell viability was promoted by GO, but in nGO is observed a mild damage in the HDFs cells independent of nGO concentration and light exposure. The unique properties of GO and nGO may be useful for the clinical treatment of disinfection of broad-spectrum antimicrobials. The antibacterial results of PTT and PDT using GO in gram-positive and gram-negative bacteria, using low dose light, allow us to conclude that GO and nGO can be used in dermatologic infections, since the effect on human dermal fibroblasts of this treatment is low compared to the antibacterial effect.

Imidazolium groups were successfully prepared and grafted on the surface of SBA-15 mesoporous silica. The ion-exchange properties of the functionalized porous solid (SBA-15/R(+)Cl(-)) toward AuCl(4)(-) anions were evaluated through an ion-exchange isotherm. The calculated values of the equilibrium constant (log β = 4.47) and the effective ion-exchange capacity (t(Q) = 0.79 mmol g(-1)) indicate that the AuCl(4)(-) species can be loaded and strongly retained on the functionalized surface as counterions of the imidazolium groups. Subsequently, solids containing different amounts of AuCl(4)(-) ions were submitted to a chemical reduction process with NaBH(4), converting the anionic gold species into supported gold nanoparticles. The plasmon resonance bands, the X-ray diffraction patterns, and transmission electron microscopy images of the supported gold nanoparticles before and after thermal treatment at 973 K indicate that the metal nanostructures are highly dispersed and stabilized by the host environment.

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The rich plasmon resonance modes and local field enhancements of two-dimensional (2D) noble metal nanostructures have boosted their application in distinct areas like catalysis, photonics, medicine and sensing. Here, we develop a unique strategy for the controlled growth of asymmetric 2D gold nanostructures in aqueous media using graphene oxide as a template. By performing mild reduction of gold ions on the surface of Au seeds (∼2 nm) attached to graphene oxide nanosheets, the anisotropic growth of 2D gold nanostructures can be carried out through a simple procedure with a tunable control of the final size, shape and thickness, and consequently on their optical properties, without using surfactants.

Nanometric ceria-decorated SBA-15 was prepared using a route involving the impregnation of SBA-15 pores by a solution of cerium(III) 2-ethylhexanoate, followed by its thermal decomposition. According to XRF analysis, the number of successive impregnation-decomposition cycles (IDC) allows control of the CeO 2 /SiO 2 ratio in the final material, and also the tailoring of the nanoparticle size of the fluorite CeO 2 nanoparticles supported in the SBA-15, as confirmed by XRD, Raman and UV-Vis spectroscopies. The mean pore size of the SBA-15 decreases with successive IDC, as observed by N 2 adsorption-desorption, suggesting that CeO 2 nanoparticles are located inside the SBA-15 mesopores, as confirmed by TEM and HRTEM analyses. The degree of oxygen storage capacity (OSC) was measured by the number of hydrogen uptake from the temperature programmed reduction (H 2 -TPR). It was found that the value of hydrogen uptake of SBA-15 submitted to one IDC corresponds to 3344 mmol of O 2 per gram of CeO 2 , whereas those of SBA-15 submitted to five and ten IDC were 1324 and 2769 mmol of O 2 per gram of CeO 2 , respectively.

This work presents an in situ route to electrochemically prepare an oxidized carbon surface from glassy carbon electrodes (GCEs), which generates a material with a similar electrochemical response as graphene oxide. The proposed in situ route is fast, simple, environmentally friendly and consists in applying a potential of +1.8 V vs. SCE to a GCE. The oxidized electrode surface (GCEOS) and its subsequent electrochemical reduction (GCEERS) can be accomplished easily and efficiently by electrochemical techniques. GCEOS and GCEERS were characterized by electrochemical, spectroscopic and microscopy techniques, revealing the in situ origin of the material and confirming its chemical similarity to the graphene oxide prepared by the Hummers and Tour methods. The presence of a 2D atomically thick material was not observed, which strongly indicates that the electrochemical response of graphene oxide resides only in the oxygenated functional groups. The remaining oxygenated groups in GCEERS show a drastic cathodic shift of potential (542 mV) for nicotinamide adenine dinucleotide (NADH) electrooxidation.