Ni2FeS4 as a highly efficient earth-abundant co-catalyst in photocatalytic hydrogen evolution

Abstract

The earth abundant sulphide Ni₂FeS₄ was used as a highly efficient co-catalyst for the hydrogen evolution reaction (HER) over TiO₂, boosting the activity of pure TiO₂ (P25) by a factor of more than 8 under AM 1.5G simulated sunlight, thus presenting a promising alternative to platinum or rhodium co-catalysts. Low metal-sulphide loadings of only 0.5 wt% (0.29 wt% of metals) could be realised, thereby rivalling common loadings of noble metal co-catalysts at significantly lower material costs. The performance was stable under 1 sun irradiation and no decrease in the activity was observed over 20 h of irradiation. The synthesis of Ni₂FeS₄ is based on low-cost precursors and can be completed after only 1 min at 200 °C in the microwave, without need for toxic H₂S, presenting an energy efficient and cost-effective possibility to obtain large amounts of such co-catalysts in a short time. This combination of a fast and cheap synthesis together with a high efficiency and stability makes Ni₂FeS₄ an outstanding candidate for the use as co-catalyst for the HER with sunlight.