Electrocatalysis: Synthesis to Devices

Materials

MXenes

MXenes are a relatively new family of 2D materials (1 to 3 layers), which are made up of transition metal carbides and nitrides, produced from MAX phases by various etching processes, Figure X. A MAX phase has the general formula of Mn+1AXn where the M is an early transition metal, the A is an element from group 13 and 14 of the periodic table, and the X represents a carbon or nitrogen. During the etching process, done in a fluoride ion based solution, the element from group 13/14 is removed from the MAX structure causing the carbide layers to become terminated by OH-, O- , Cl- or F- groups which are subsequently called ‘surface groups or edge sites’.5 The resulting structure is known as a ‘MXene’. MXenes are known to be highly conductive and durable due to their structures. However, to date MXenes are not known to contain active sites for the OER, as no MXenes with metals for promoting the OER (e.g. Mn or Fe) have been successfully synthesised.  On the other hand, Transition metal oxides (TMOs) are an exciting group of materials that possess various intriguing physical properties that can change depending on the oxidation state of the material and are known to be active water splitting catalysts. By combining inexpensive, active TMO catalyst with MXenes, Our group creates catalyst layers with characteristics of a desired OER catalyst.