Metal-modified Transition Metal Carbides for Electrochemical Applications

Proton exchange membrane or anion exchange membrane water electrolyzers and fuel cells are still expensive for large-scale commercialization. It requires more investigation and research on finding more economical and efficient electrocatalysts for reactions in these devices. This thesis investigates the performance of metal-modified transition metal carbides on hydrogen evolution reaction (HER) and ethanol oxidation reaction (EOR). The catalysts screening principles for HER and EOR in acid and alkaline are examined and developed by correlating density functional theory (DFT) calculations with experimental results. Metal-modified transition metal carbides can reduce the amount of platinum group metals required for HER, but it is unclear what descriptors are relevant for these materials for the HER under alkaline conditions. Several transition metal carbides (Mo2C, NbC, TaC, WC, VC) thin films were synthesized and modified with monolayers of platinum or gold. The experimentally measured HER exchange current densities were compared with DFT calculations of adsorbed hydrogen and hydroxyl binding energies. The plot of HER activity versus hydrogen binding energy showed a volcano shape fo