Editorial pubs.acs.org/JPCL
Physical Chemistry at the Interface Prashant V. Kamat, Deputy Editor
C
hemistry at the interfaces continues to draw significant attention because of the intriguing nature of chargetransfer processes involved. The chemical processes can be simply manipulated by changing the nature of the interface involved. For example, in the electrocatalytic reduction of CO2, the final desired product can be tailored by the type of metal electrode employed.1 While many surface chemistry techniques probe the interfacial processes at the solid surfaces, electrochemistry by far offers a simple and convenient tool to probe the heterogeneous charge-transfer processes at the metal (or semiconductor) electrode/liquid interface. The three Perspectives in this final issue of 2015 offer different aspects of interfacial chemistry. Musgrave and coworkers (J. Phys. Chem. Lett. 2015, 6, 5078−5092) provide a theoretical and experimental perspective of the catalytic reduction of CO2 to methanol using dihydropyridines as organohydride reducing agents in an electrochemical experiment. The 6e−/6H+ reduction of CO2 to methanol involves a series of electron-coupled proton-transfer steps. According to Musgrave and co-workers, a hydride-transfer and protontransfer sequence facilitates protonation of the reduced intermediates, thus avoiding the formation of radical intermediates. Although other researchers offer alternate explanations on the reduction mechanism,2,3 Musgrave and co-workers present their view of pyridinium/dihydropyridinium as a redox couple similar to NADPH/NADP+ driving the hydride-transfer reaction. Rotenberg and Salanne, in their Perspective, provide insight into the changes in ionic liquid layers adsorbed on the electrode surface and their impact on physical and electrochemical properties (J. Phys. Chem. Lett. 2015, 6, 4978−4985). Room-temperature ionic liquids that serve the role of solvent and electrolyte are important in electrochemistry as they offer a wide electrochemical window for reduction and oxidation processes. However, adsorption of multilayers of ionic liquid on metal electrodes with voltage-responsive changes in the first layer makes the interfacial chemistry more challenging to predict. Such changes bring about interfacial changes in terms of differential capacitance, redox potentials, and electrochemical processes. Synthesis and characterization of nanoparticles of different size and shape have dominated nanoscience research for last two decades. Most of these studies have relied on ex situ techniques (XRD, TEM, XPS, absorption and emission spectroscopy, etc.) to predict the nucleation and growth mechanism of nanostructure formation. A more rigorous in situ technique, however, can offer a direct window to probing the formation of different nanostructures. Ngo and Yang present in situ liquid transmission electron microscopy (LTEM) that enables the quantitative study of nanocrystal formation in solution (J. Phys. Chem. Lett. 2015, 6, 5051− 5061). By showcasing a few selected examples, they discuss the capabilities of LTEM. The availability of this and other in situ techniques should further facilitate the design of tailored nanostructures. © 2015 American Chemical Society
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University of Notre Dame, Notre Dame, Indiana 46556, United States
AUTHOR INFORMATION
Notes
Views expressed in this editorial are those of the author and not necessarily the views of the ACS.
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RELATED READINGS
(1) Peterson, A. A.; Norskov, J. K. Activity Descriptors for CO2 Electroreduction to Methane on Transition-Metal Catalysts. J. Phys. Chem. Lett. 2012, 3, 251−258. (2) Ertem, M. Z.; Konezny, S. J.; Araujo, C. M.; Batista, V. S. Functional Role of Pyridinium during Aqueous Electrochemical Reduction of CO2 on Pt(111). J. Phys. Chem. Lett. 2013, 4, 745−748. (3) Lessio, M.; Carter, E. A. What is the Role of Pyridinium in Pyridine-Catalyzed CO2 Reduction on p-GaP Photocathodes? J. Am. Chem. Soc. 2015, 137, 13248−13251.
Published: December 17, 2015 5093
DOI: 10.1021/acs.jpclett.5b02571 J. Phys. Chem. Lett. 2015, 6, 5093−5093
