Exfoliated Fe3GeTe2 and Ni3GeTe2 materials as water splitting electrocatalysts

Two dimensional layered metallic Fe3GeTe2 (FGT) and Ni3GeTe2 (NGT) are expected to be water- and air-stable. Very recently, it has been predicted that FGT possesses exposed active sites on its basal plane which can provide excellent oxygen evolution reaction (OER) activity, with a low OER overpotential of 0.30 V, following surface hydroxyl pathways. NGT has a similar chemical and crystalline structure; however, its performance as an electrochemical catalyst is not yet reported. Thus, FGT and NGT were synthesized by solid-state reaction and, for the first time, exfoliated by shear force. The prepared materials were investigated as electrocatalysts, thus comparing the catalytic performance of MGT materials, bulk and exfoliated counterparts, towards the hydrogen evolution reaction (HER) and oxygen-involving reactions (OER and the oxygen reduction reaction). Ferromagnetic transitions and Curie-Weiss contributions were noticed in FGT and NGT, respectively, in the analysis of their temperature dependent magnetic susceptibility. For the HER, exfoliated FGT has superior catalytic activity in alkaline media and for OER, improved catalytic activity was attained by using more conductive supports as compared with the glassy carbon substrate. FGT achieved the best OER performance, in agreement with the theoretically predicted value following the classical pathway in alkaline media.

Automated summary

It has been found that two-dimensional layered metallic materials Fe3GeTe2 and Ni3GeTe2 have stable water- and air-stability. Fe3GeTe2 has shown excellent oxygen evolution reaction (OER) activity, while the electrochemical catalytic performance of Ni3GeTe2 has not been reported. Single-layered FGT was obtained through exfoliation, showing superior catalytic activity in alkaline media. FGT achieved the best performance in OER, consistent with theoretical predictions.