Electrocatalysis fundamental parameters

Dr. Horanyi reviews a fundamental area of electrocatalysis, one in which there is a solid-fluid boundary. He presents a thorough review of the key parameters in this field and provides background information and nomenclature for the uninitiated. 

The main basic parameter of catalyst evaluation is the specific exchange current density which, by definition, is normalized to the unit surface area of the electrocatalyst. This property is the target of many fundamental studies in electrocatalysis, too numerous to be listed (Adzic et al., 2007 Debe, 2013 Gasteiger and Markovic, 2009 Kinoshita, 1992 Paulus et al., 2002 Stamenkovic et al., 2007a,b Tarasevich et al., 1983 Zhang et al., 2005, 2008). 

In conclusion, the main challenge in the design of nanoporous materials for UTCLs is to fine-tune the proton concentration in order to optimize the interplay of ORR and Pt dissolution. This fundamental principle has not been widely realized, as most efforts in fuel cell electrocatalysis compare candidate catalyst materials at identical and normally high proton concentration. Proton concentration is usually not considered a parameter to tinker with although it is the key card in the game. 

It is well known that the maximum efficiency of electrochemical devices depends upon electrochemical thermodynamics, whereas real efficiency depends upon the electrode kinetics. To understand and control electrode reactions and the related parameters at an electrode and solution interface, a systematic study of the kinetics of electrode reactions is required. When ILs are used as solvents and electrolytes, many oftheelectrochemical processes will be differentandsomenewelectrochemical processes may also occur. For example, the properties of the electrode/electrolyte interface often dictate the sensitivity, specificity, stability, and response time, and thus the success or failure of the electrochemical detection technologies. The IL/electrode interface properties will determine many analytical parameters for sensor applications. Thus, the fundamentals of electrochemical processes in ILs need to be studied in order to have sensor developments as well as many other applications such as electrocatalysis, energy storage, and so on. Based on these insights, this chapter has been arranged into three parts (1) Fundamentals of electrode/electrolyte interfacial processes in ILs (2) Experimental techniques for the characterization of dynamic processes at the interface of electrodes and IL electrolytes and (3) Sensors based on these unique electrode/IL interface properties. And in the end, we wiU summarize the future directions in fundamental and applied study of IL-electrode interface properties for sensor applications. 

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