Physical and chemical properties of graphene can be tailored by nitrogen doping. As a consequence of the continuous race to achieve the highest possible amount of doping there is a growing tendency to assume that all N species are incorporated within the graphene lattice (doping). Here we show that this is not always the case and employ several complementary techniques that allow a proper assessment of the type of nitrogen present. The nature of the nitrogen atoms has been tuned by ammonolysis of graphene oxide in the range of 100 °C–800 °C. This allows us to expand the capabilities of the synthetic approach to afford not only N-doping (at high temperature) but also to introduce amine and amide moieties at 100 °C; the latter presenting a much higher dispersability in aqueous media than graphene oxide. Interestingly, the sample with the highest amount of nitrogen (14.7 wt. %) cannot be referred to as N-doped graphene since it also contains N-bearing aliphatic moieties.We acknowledge financial support from MINECO (grants ACI2009-0861 and MAT2014-53500-R, Spain) and Department of Science and Technology (DST, India). This work has been carried out under the Materials Science PhD program of the Universitat Autònoma de Barcelona (UAB). The XPS data were acquired at the Laboratorio de Microscopías Avanzadas (LMA) - Instituto de Nanociencia de Aragón (INA), and EA in the Centres Científics i Tecnològics - Universitat de Barcelona, both in Spain.Peer reviewe

Over the last few years, research on silica nanoparticles has rapidly increased. Particularly on mesoporous silica nanoparticles (MSNs), as nanocarriers for the treatment of various diseases because of their physicochemical properties and biocompatibility. The use of MSNs combined with therapeutic agents can provide better encapsulation and effective delivery. MSNs as nanocarriers might also be a promising tool to lower the therapeutic dosage levels and thereby to reduce undesired side effects. Researchers have explored several routes to conjugate both imaging and therapeutic agents onto MSNs, thus expanding their potential as theranostic platforms, in order to allow for the early diagnosis and treatment of diseases. This review introduces a general overview of recent advances in the field of silica nanoparticles. In particular, the review tackles the fundamental aspects of silicate materials, including a historical presentation to new silicates and then focusing on the key parameters that govern the tailored synthesis of functional MSNs. Finally, the biomedical applications of MSNs are briefly revised, along with their biocompatibility, biodistribution and degradation. This review aims to provide the reader with the tools for a rational design of biocompatible MSNs for their application in the biomedical field. Particular attention is paid to the role that the synthesis conditions have on the physicochemical properties of the resulting MSNs, which, in turn, will determine their pharmacological behavior. Several recent examples are highlighted to stress the potential that MSNs hold as drug delivery systems, for biomedical imaging, as vaccine adjuvants and as theragnostic agents.

Thermal analysis is widely employed for the characterization of nanomaterials. It encompasses a variety of techniques that allow the evaluation of the physicochemical properties of a material by monitoring its response under controlled temperature. In the case of carbon nanomaterials, such as carbon nanotubes and graphene derivatives, thermogravimetric analysis (TGA) is particularly useful to determine the quality and stability of the sample, the presence of impurities and the degree of functionalization or doping after post-synthesis treatments. Furthermore, TGA is widely used to evaluate the thermal stability against oxidation by air, which can be, for instance, enhanced by the purification of the material and by nitrogen doping, finding application in areas where a retarded combustion of the material is required. Herein, we have evaluated key parameters that play a role in the data obtained from TGA, namely, gas flow rate, sample weight and temperature rate, used during the analysis. We found out that the heating rate played the major role in the process of combustion in the presence of air, inducing an increase in the temperature at which the oxidation of CNTs starts to occur, up to ca. 100 °C (from 1 °C min⁻¹ to 50 °C min⁻¹). The same trend was observed for all the evaluated systems, namely N-doped CNTs, graphene produced by mechanical exfoliation and N-doped reduced graphene samples. Other aspects, like the presence of impurities or structural defects in the evaluated samples, were analyzed by TGA, highlighting the versatility and usefulness of the technique to provide information of structural aspects and properties of carbon materials. Finally, a set of TGA parameters are recommended for the analysis of carbon nanomaterials to obtain reliable data.

This work compares various methods to prepare polymer/carbon nanotube (CNT) composites for\ud thermoelectric applications, focusing on the different doping mechanisms. We\ud first look at the general\ud trends observed in the Seebeck coefficient and power factor for a large number of composites as a\ud function of electrical conductivity. Then we discuss two methods of nitrogen doping the carbon\ud nanotubes in these composites, namely either during synthesis, or afterwards by ammonolysis. Finally,\ud we discuss doping of the carbon nanotubes through charge transfer from the polymer counterpart,\ud including photo-induced switching of the majority carrier type. As a general remark, we note that\ud processability is negatively influenced by some doping procedures. Best results were achieved for\ud unfunctionalized single-walled carbon nanotubes with a high content of semiconducting CNT species.The authors would like to thank Prof. Michael L. Chabinyc, Prof.\ud Christian Müller and Prof. Alejandro R. Goñi for useful discussions.\ud We are grateful to John D. Craddock, Prof. Matthew C. Weisen-\ud berger and Prof. John E. Anthony for providing the n-MWCNTs. The\ud authors would also like to acknowledge\ud financial support from the\ud Ministerio de Economía y Competitividad of Spain through\ud projects CSD2010–00044 (Consolider NANOTHERM), MAT2015-\ud 70850-P and MAT2014-53500-R; and the European Research\ud Council (ERC) under grant agreement no. 648901. S. Sandoval\ud acknowledges a contract though PIE 201660E013 and P. Kankla the\ud Development and Promotion of Science and Technology Talents\ud Project (DPST). We are grateful to Thomas Swan Co. Ltd for\ud supplying Elicarb1 SWCNTs.Peer reviewe