New oxometalate-based materials for catalysis and electrocatalysis

Abstract

Two series of new oxometalate-based materials are described. It is shown that numerous electronic conductors or semiconductor electrodes can be easily electromodified in the presence of various compounds of the oxometalate series. Upon modification, materials usually known to be poor hydrogen cathodes or photocathodes show strikingly high exchange current densities for the h.e.r.. The enhanced kinetics for this process is mainly attributed to the electrodeposited catalysts because it appears as largely independent from the nature of the starting electrode material. The modified surfaces are robust and very durable, and have been characterized by electrochemistry and several complementary physical techniques. The second class of materials is constituted by surfaces which are functionalized by oxometalates entrapped in polymeric matrices. Electronically-conductive as well as non-conductive polymers are suitable for this purpose. It appears that the inclusion of oxometalates generates new polymers which can be interesting by themselves. It is also shown that the entrapped oxometalates retain all their known properties and exhibit enhanced redox catalysis effects. The h.e.r. and the oxygen reduction process are taken as examples. Finally, the catalyst electrodeposited in the first class of materials is also easily obtained in polymeric matrices.