H Induced Metal-Insulation Transition Boosts the Stability of High Temperature Polymer Electrolyte Membrane Fuel...

High temperature polymer electrolyte membrane fuel cells (HT-PEMFCs) have garnered significant attention due to their expanded range of hydrogen sources and simplified management systems. However, the frequent start-up and shut-down (SU/SD) caused fuel starvation operation condition seriously deteriorates the performance and lifetime of the fuel cell. In this manuscript, VO₂ was incorporated in the anode to restrain fuel starvation of the electrode. Under the operation condition, the insulative VO₂ would reversibly transform into metallic H_xVO₂ by intercalating hydrogen, and H_xVO₂ can automatically release hydrogen, which could act as the hydrogen buffer and suppress reverse-current degradation. After the hydrogen release, the generated insulating VO₂ would prevent the side reactions during fuel starvation. Compared to the traditional Pt anode, the electrode with VO₂ showed much higher output power and greatly improved durability after fuel starvation. This work demonstrates the in situ reversible hydrogen storage/release-controlled metal-insulator phase transition strategy to enhance the durability of fuel cells.