Breaking symmetry with bipolar electrochemistry: Concepts and applications Laurent Bouffier Université de Bordeaux, Institut des Sciences Moléculaires, UMR CNRS-5255, FRANCE The concept of bipolar electrochemistry (BPE) has been known for decades, but was only exploited with respect to very specific industrial applications such as electrolysis, corrosion or batteries. More recently, this technique has attracted an increasing interest in broader areas such as materials fabrication or analytical sensing [1,2]. Unlike conventional electrochemistry, BPE occurs when a conducting object is immersed into an electrolyte solution and submitted to an external electric field. If the strength of the field is large enough, redox processes can take place on both side of the object even if there is no direct contact with the power supply. It is therefore a very unique wireless approach that can be advantageously used to address electrochemically conducting objects in solution. We will first show that BPE can be used for preparing asymmetric Janus-type materials based on the selective deposition of various chemical species at one extremity of a conducting object . This could be achieved under several experimental conditions in order to tailor the chemical nature, composition and structure of the corresponding deposited layers . In some cases, the deposition of electro-inactive precursors could equally be achieved by BPE based on the generation of pH gradients at the vicinity of a bipolar electrode . Moreover, the control of the deposition mechanism allows the bulk production of smart particles exhibiting an original morphology that cannot be obtained by other physical chemistry approaches . Actually, any kind of redox reactions can be promoted on a bipolar electrode. This will be illustrated by using additional chemical species capable to emit light following a series of reactions initiated by an electron transfer step (electrochemiluminescence, ECL) . The potentialities of this approach will be illustrated with two applications. The first one is the design of dynamic systems where the motion of a bipolar electrode is driven by BPE concomitantly with ECL light emission [8-10]. Secondly, increasing the number of bipolar emitters addressed simultaneously by BPE leads ultimately to a bulk ECL emission in the whole volume of the solution, which can potentially open the door to high-sensitivity analytical applications [11,12]. Fig. Carbon/Gold Janus particle prepared by site-selective bipolar electrodeposition (left); Copper morphology gradient on a carbon microfiber (center) and 3D bulk electrochemiluminescence generated by wireless addressing of thousands of conducting emitters (right). References     G. Loget, D. Zigah, L. Bouffier, N. Sojic, A. Kuhn, Acc. Chem. Res., 2013, 46, 2513. S. E. Fosdick, K. N. Knust, K. Scida, R. M. Crooks, Angew. Chem. Int. Ed., 2013, 52, 10438. Z. Fattah, P. Garrigue, V. Lapeyre, A. Kuhn, L. Bouffier, J. Phys. Chem. C, 2012, 116, 22021. G. Tisserant, Z. Fattah, C. Ayela, J. Roche, B. Plano, D. Zigah, B. Goudeau, A. Kuhn, L. Bouffier, Electrochim. Acta, 2015, 179, 276.  G. Loget, J. Roche, E. Gianessi, L. Bouffier, A. Kuhn, J. Am. Chem. Soc., 2012, 134, 20033.  J. Roche, G. Loget, D. Zigah, Z. Fattah, B. Goudeau, S. Arbault, L. Bouffier, A. Kuhn, Chem. Sci., 2014, 5, 1961.  L. Bouffier, S. Arbault, A. Kuhn, N. Sojic, Anal. Bioanal. Chem., 2016, DOI 10.1007/s00216-0169606-9  L. Bouffier, V. Ravaine, N. Sojic, A. Kuhn, Curr. Opin. Colloid. Interface Sci., 2016, 21, 57.  L. Bouffier, D. Zigah, C. Adam, M. Sentic, Z. Fattah, D. Manojlovic, A. Kuhn, N. Sojic, ChemElectroChem, 2014, 1, 95.  M. Sentic, S. Arbault, B. Goudeau, D. Manojlovic, A. Kuhn, L. Bouffier, N. Sojic, Chem. Commun., 2014, 50, 10202.  M. Sentic, S. Arbault, L. Bouffier, D. Manojlovic, A. Kuhn, N. Sojic, Chem. Sci., 2015, 6, 4433.  A. De Poulpiquet, B. Diez-Buitrago, M. Milutinovic, B. Goudeau, L. Bouffier, S. Arbault, A. Kuhn, N. Sojic, ChemElectroChem, 2016, 3, 404.