Speaker
Description
Hydrogen is one of the most promising green energy carriers. H2 can be produced without greenhouse gas emission via renewable energy-fueled electrolysis . However, in real electrochemical cells, the sluggishness of the multi-electron transfer mechanism at the cathodic and, particularly, at the anodic sites (oxygen evolution reaction, OER) increases the electrical power required to perform the reaction. For this reason, industrial electrolysis process requires effective catalysts, which are currently based on rare materials such as Ir or Ru in the OER case . Transition metal oxide (TMO) based catalysts are nowadays a valid, cost-effective alternative. TMOs with tailorable band structures are excellent candidates as photoanode materials; this option is particularly appealing, since it allows a direct solar photon-to-electron conversion, limiting the intermediate losses and the use of resources .
The synthesis of more cost-effective catalysts passes through precise doping engineering of the functional materials, combined with adequate setups capable of probing the electronic and structural dynamics of the catalyst under operando conditions. A special importance must be assigned to the catalyst/electrolyte interface. Several approaches are available. The stringent experimental requirement imposed by imaging methods or vibrational spectroscopies often makes the investigation challenging, with respect to the more straightforward approaches allowed by X-ray absorption spectroscopy (XAS).
We will describe the photoanodic performances of ultra-thin Ni-doped γ-Fe2O3 films (111) epitaxially grown on Pt (001) single crystal. The role of Ni concentration on the γ-Fe2O3 photocatalytic performances for the OER is discussed. The catalytic mechanism is investigated using the results obtained from a custom-made cell for operando XAS measurements . To unravel tiny surface-bound electronic effects, we also propose a novel pump-and-probe approach to the XAS experiments under operando conditions.
