Novel earth-abundant Cu and Fe-based chalcogenide cocatalysts for photocatalytic hydrogen evolution

While photocatalysis offers an attractive route towards the sustainable production of hydrogen (H2) and other green fuels or commodity chemicals, significant improvements in efficiency and reductions in production costs are still needed. Traditionally, noble metal cocatalysts are used to increase the activity and selectivity of a photocatalyst. In this work, we systematically investigate different nanomaterials based on the abundant and inexpensive elements Cu and Fe as cocatalysts on TiO2 (P25) for the photocatalytic hydrogen evolution reaction (HER) under simulated sunlight as well as under UV irradiation. All the investigated Cu and Fe sulfides/oxides can be obtained via simple and fast microwave-assisted synthesis. In addition, we show how further modifications, such as partial oxidation of the sulfides or doping of CuFe2O4 with Ni, can have a tremendous effect on the performance as a cocatalyst, increasing the activity by a factor of more than 15 compared to pristine TiO2 and by a factor of almost 6 compared to TiO2 equipped with undoped CuFe2O4 under AM 1.5G simulated sunlight. Under UV irradiation, an H2 evolution rate of more than 2.3 mmol h-1 was achieved. Thus, this work opens a new design platform for the synthesis of earth-abundant cocatalysts for noble metal substitution in photocatalysis.