The science and technology of catalysis is of fundamental importance to a national economy. Today about 90% of all technical chemicals are manufactured by the use of catalysts. Nanoparticles of noble metals are extremely important materials in the catalysis industry due to cost issues and properties that are not found in their bulk state. An efficient way to produce and stabilise noble metal nanoparticles is by dispersion on a suitable support. Carbon-based supports, such as carbon nanotubes, carbon spheres, carbon fibres, etc., have been found to be good supports for metal nanoparticles. However, to be used effectively, the carbon surface must be modified either by functionalisation or doping. This review discusses the synthesis and the possible applications of nitrogen-doped carbon nanotubes as supports for metal nanoparticles in heterogeneous catalysis.

The pollution of the environment by plastics is a global problem that is real and needs to be resolved urgently. The authors argue that banning the use of plastic is not a reasonable and rational solution for the problem because plastics have many useful applications. Solutions to the problem must involve developing scientific approaches as well as global efforts and strategies. The world’s approach needs to be guided by an economic model that eliminates or minimizes the amount of plastics in the waste stream. As long as most plastic materials are not made from a single polymer, then the idea of “recycling 100% of plastics” is so far an unrealistic solution. The development of biodegradable plastics is still far from being an effective solution because besides being expensive and having limitations in engineering applications when compared to petroleum-based ones, biodegradable plastics still require specific conditions for their biodegradation. Comprehensive studies on microplastic particles are needed, focusing mainly on the source of the particles, their distribution, transport, fate in different environments, and toxicological effects and mechanisms. Since plastic pollution is a global problem, its minimization will require an increased international cooperation platform and partnerships at a global level. While current technologies and strategies are not solving the environmental problem caused by waste plastic, the most effective solution would be to adopt the first two levels of the waste management hierarchy, which are “reduce” and “reuse”.

This review covers recent advances on production techniques, unique properties and novel applications of nitrogen-doped graphene oxide (NGO). The focal point is placed on the evaluation of diverse methods of production for NGO and reduced nitrogen-doped graphene oxide (NrGO) nanosheets using GO and graphite as carbon precursors. Variation in chemical composition of GO with variable N content, C–N bonding configurations and chemical reactive functionalities of NGO allow tuneable properties that render NGO a suitable material for various applications such as lithium-ion batteries, biosensors, supercapacitors and adsorption processes. NGO and NrGO exhibit significantly different performances compared to GO even with small amounts of N-doping. The type of C–N bonding and surface chemistries on the NGO are responsible for their unique electrical, mechanical, adsorption, chemical reactivity, photocatalytic activity, and optical properties. Various investigative techniques used to study NGO nanomaterials are also reviewed. Finally, future perspectives of NGO in this rapidly developing area are discussed. Graphical abstract Methods of synthesis of N-doped graphene oxide nanosheets and their advantages and disadvantages.