Demonstration of the potential for gas-tight reduced graphene oxide and graphene oxide films: From windows for X-ray devices to proton exchange membranes for fuel cells

The evaporation-assembly process of graphene oxide suspensions has been used to develop gas-tight, self-supporting films with areas spanning several tens of square centimeters, showcasing remarkable properties. A detailed analysis has been conducted on the characteristics and specific features of these laminates. The initial suspension of graphene oxide and its processing history are crucial in determining the resulting physicochemical properties of the films and the carbon-to-oxygen (C/O) ratios on their surfaces. This variability is attributed to the structural dynamism of the graphene oxide flakes. Furthermore, the thermal stability and reducibility of the surface functional groups within these laminates have been thoroughly investigated. Notably, environmentally benign reagents for reduction, such as ascorbic acid, significantly enhance the C/O ratios more than thermal treatment. While the as-prepared graphene oxide membranes demonstrate high electrical resistivity, their in-plane electrical conductivity is notably superior in films reduced with ascorbic acid compared to those produced through alternative methods. The properties of these films hold promise for a variety of applications. Reduced graphene oxide films, characterized by low in-plane electrical resistivity, have been effectively utilized in proportional counters to precisely measure low-energy X-ray emission rates, as a substitute for hazardous and fragile beryllium windows. Additionally, the developed graphene oxide membranes have been successfully implemented as proof of concept of proton exchange membranes in fuel cells. • Gas-tight cross-linked graphene oxide membranes with areas up to 100 cm 2 have been successfully synthesized and characterized in depth. • Efficient reduction of the prepared layers with an environmentally friendly reducing reagent such as ascorbic acid provides films showing outstanding conductivity values above 30000 S·m -1 . • Highly conductive and gas-tight reduced graphene oxide films are good candidates to replace fragile and toxic beryllium windows in X-ray devices. • Non-conductive gas tight graphene oxide films are able to operate as proton exchange membranes in a fuel cell constituting a promising alternative to noxious perfluoroalkyl polymers.