sentences:  Platinum black powder is used as a catalyst in proton-exchange membrane fuel cells.In common practice, the platinum black is either sprayed using an ultrasonic nozzle or hot pressed onto the membrane or gas diffusion layer.A suspension of platinum black and carbon powder in ethanol-water solutions serves to optimize the uniformity of the coating, electrical conductivity, and in the case of application to the membrane, to prevent dehydration of the membrane during the application.