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Developments in chemistry, materials science and biology have been fuelled by our search for structure–property relationships in matter at different levels of organization. Transformations in chemical synthesis and living systems predominantly take place in solution, such that many efforts have focused on studying nanoscale systems in the liquid phase. These studies have largely relied on spectroscopic data, the assignment of which can often be ambiguous. By contrast, electron microscopy can be used to directly visualize chemical systems and processes with up to atomic resolution. Electron microscopy is most amenable to studying solid samples and, until recently, to study a liquid phase, one had to remove solvent and lose important structural information. Over the past decade, however, liquid-phase electron microscopy has revolutionized direct mechanistic studies of reactions in liquid media. Scanning electron microscopy and (scanning) transmission electron microscopy of liquid samples have enabled breakthroughs in nanoparticle chemistry, soft-matter science, catalysis, electrochemistry, battery research and biochemistry. In this Review, we discuss the utility of liquid-phase electron microscopy for studying chemical reaction mechanisms in liquid systems. Liquid-phase electron microscopy is a powerful method for the direct, real-time monitoring of chemical processes on nanometre and micrometre scales. This Review describes the liquid-phase electron-microscopy techniques available to us and their application to studying chemical processes.

A new approach for the catalytic carbon–sulfur bond formation via cross-coupling reaction is reported. For the first time nano-structured nickel organosulfides [Ni(SAr)2] n were used as a source of SAr groups in catalytic cross-coupling reaction. A unique effect of morphology control of the reactivity of SAr groups in cross-coupling reaction was found. Synthesized nano-structured particles were characterized by field-emission scanning electron microscopy and their reactivity was studied by NMR in solution. Cross-coupling reaction with Cu catalyst was shown to proceed in the liquid phase and involve leaching, whereas the reaction with Pd catalyst is more complex and may involve both—homogeneous and heterogeneous pathways.

Magnetron sputtering was successfully used to obtain nanosized metal films and metal nanoparticles, which can be useful for development of novel methods in organic chemistry. The morphology of the nanosized (5–100 nm) objects obtained was examined by SEM. The pattern of dependence of the morphology and size of the nanosized objects on the nature of the support surface, the metal, and the sputtering conditions is described.