Solid state protonic conductors, present main applications and future prospects

A brief overview of the past and present state of art in the field of solid state protonic conductors is reported. Less attention is given to theoretical aspects of the proton conduction and to high temperature materials (perovskite-like oxide ceramics) because these subjects have been well-treated in recent reviews. More emphasis is instead given to proton conducting materials in the temperature range 20–350°C, including the recent hybrid membranes. Particular attention has been reserved for the latest developments on SSPC sensors at low, medium and high temperature, as well as for PEM fuel cells at low and medium temperature. Some prospects for the near future, especially for SSPC polysensors, protonic pumps and PEM fuel cells at low and medium temperature are also reported.