Enhanced PEC Activity\nof Hematite\nPhotoanodes Driven by Improved Charge-Transfer Dynamics Investigated\nUsing IMPS/IMVS

Solar energy is one of the most effective and promising\noptions\namong the renewable energy sources and has nearly unlimited availability;\nhowever, it is challenging to harvest it in a sustainable manner.\nThe generation of hydrogen and oxygen using solar light to split water\nis a prominent way to harvest solar energy and use hydrogen as the\nfuel, subjected to the development of cost-effective and efficient\nhydrogen evolution and oxygen evolution catalysts. Catalysts composed\nof noble metals are efficient for the hydrogen evolution reaction\n(HER) and oxygen evolution reaction (OER), but their use is economically\nnot viable for commercial applications. The material should therefore\nbe from earth-abundant sources; iron oxide scores the best as a promising\nphotoelectrochemical (PEC) catalyst with the highest earth abundance\nindex. The evaluation of the PEC catalytic performance involves measurements\nof several kinetic and efficiency parameters. The present manuscript\nfocuses on the investigation of such kinetic parameters using two\nimportant spectroscopic tools: intensity-modulated photocurrent spectroscopy\nand intensity-modulated photovoltage spectroscopy. Iron oxide photoanodes\nwith different thicknesses generated using an electrochemical deposition\nroute are used as the photoanode material. These two spectroelectrochemical\ntools are used to explain the enhanced catalytic performance at 1\nμm thickness of the hematite film through the measurement of\nthe charge transfer and recombination kinetics to explain the thickness-dependent\nPEC catalytic performances.