Comparative electrocatalytic behavior of mesoporous FeP and FeS2 for the hydrogen evolution reaction

FeP nanoparticles and FeS2 nanospheres with mesoporous surface are synthesized, and their performance is compared for the hydrogen evolution reaction under identical electrochemical conditions. The activity-determining characteristics of the electrodes, such as specific and electrochemically active surface area, electrochemical impedance and charge transfer resistance, Tafel slopes, number of catalytic active sites, and turnover frequency (TOF) are studied and correlated to their activity. Because of its larger surface area and reduced charge transfer resistance, the FeS2 showed superior HER performance than the FeP, despite the latter's higher intrinsic catalytic activity. The electrocatalytic stability of the electrocatalysts are also compared.