Gd Active Sites Modulating the Intermediate Adsorption and Activation in Exfoliated Gadolinium Telluride for Oxygen Evolution and Reduction Reactions

This study reveals the synthesis of gadolinium telluride (Gd2Te3), a non-noble metal alloy with a two-dimensional (2D) morphology, for the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR). 2D Gd2Te3 exhibits promising electrocatalytic activity for OER with an onset potential of 1.335 V vs RHE (η = 105 mV) and an overpotential of 1.459 V vs RHE (η = 229 mV) at 10 mA/cm2, rivalling benchmark catalysts such as IrO2 and RuO2. Gd2Te3 exhibited a large turnover frequency of 3.7 s–1 (at η = 420 mV) and a mass activity of 18.69 Ag1– (at η = 470 mV). The chronoamperometric durability studies revealed a consistent current density (>20 mA cm–2) for 8 h at 1.65 V, reflecting good electrocatalytic stability of the material. The competitive OER activity of 2D Gd2Te3 can be attributed to better valence and conduction band edge alignment with water oxidation–reduction levels that is also corroborated by density functional theory (DFT) studies. 2D Gd2Te3 also exhibited good ORR performance exhibiting an onset potential of 0.72 V vs RHE at 0.1 mA cm–2. The number of electron transfers, calculated from H2O2 percentages between 0.30 and 0.50 V vs RHE, revealed that Gd2Te3 follows the 4e– ORR pathway with OH– as the major intermediate product. Using DFT calculations, we further elucidate the role and importance of Gd in stabilizing and destabilizing the intermediates that reduce the overpotentials for both the OER and ORR.