Best Practices for the Reporting of Colloidal Inorganic Nanomaterials

Best Practices for the Reporting of Colloidal Inorganic Nanomaterials M etallic nanoparticles have been used by humanity for centuries, with the classic examples from antiquity represented by the Roman Lycergus Cup, 1 medieval stained glass windows, 2 and Faraday's work on colloidal gold in the 1870s.3 In the twentieth century, colloidal metal nanoparticles were then heavily used in the area of catalysis, long before the term "nanoparticle" was coined, an application that remains an extremely active area of research.[4][5][6][7][8] In the last three decades, since the first description by Brus and co-workers at Bell Laboratories, 9,10 semiconductor quantum dots have been the focus of a great deal of interest for optical and imaging applications 11,12 and now for energy capture in photovoltaics, among others.13 With respect to the synthesis of colloidal inorganic nanoparticles, the first well-defined and now iconic preparations of silica particles by Stober 14 and gold nanoparticles by Turkevich 15 paved the way for new routes that led to the development of a myriad of colloidal semiconductor quantum dots 16 and size-and shape-controlled metallic nanoparticles.17,18 Gold nanoparticles are now being used for a variety of applications, including medical therapies, 19 control of light (plasmonics), 20 sensing (SERS), 21 and many others.At present, thousands of papers are published every year that report new, expanded, or improved colloidal syntheses of increasing complex metallic, semiconducting, and oxide nanoparticles, with control over size, shape, composition, and surface chemistry.With increasing concerns regarding the reproducibility of new syntheses, 22 reviewers and readers of papers that describe the synthesis of colloidal nanoparticles now have rising expectations of what characterization methods need to be used when new or modified materials are reported in the literature.23 While the number of possible combinations of materials prevents us from capturing every possible scenario, we do believe that the following represent the minima that should be included; additional spectroscopic data or experimental/ procedural information will almost certainly be required by different fields.There will be cases when a specific technique cannot be performed due to limited material, high reactivity, or other reasons, and in these situations authors should be clear as to why such data cannot be provided and what the resulting uncertainties are (with regards to, for instance, composition, size, etc.).