Catalyst poisoning 1 Cathodes 1 Critical operating condition 1 Fuel cell system 1 Fuel systems 1 Gas fuel purification 1 Hydrogen 1 Irreversible degradation 1 Mitigation strategy 1 Molecular biology 1 NO 1 Nitrogen monoxide Operating condition 1 PEM fuel cell 1 Proton exchange membrane fuel cells (PEMFC) 1 Proton-exchange membranes fuel cells 1 Recovery 1 Reversible degradation 1 Temperature 1 Voltage loss 1 Voltage recovery 1 catalyst poisoning 1 critical operating conditions 1 hydrogen 1 irreversible degradation 1 mitigation strategies 1 reversible degradation 1 voltage loss 1 voltage recovery 1