Engineering discarded thermoelectric legs for sustainable hydrogen evolution

With the increase in the complexity of materials used in various sophisticated electronic devices, recycling of e-waste is increasingly challenging. In the present study, we have converted thermoelectric (TE) waste into a functional hydrogen evolution reaction (HER) electrocatalyst by considering a circular-economy and low-carbon approach. The as-received TE waste was processed through ball milling (TE waste-BM) and melting-casting (TE waste-M) routes. Morphological and structural evaluations revealed that the formation of a BiSbTe₃/ZnTe heterostructure in TE-waste-M promotes HE efficiency when compared to the presence of a Bi₂Te₃/BiSbTe₃ heterostructure (TE-waste-BM). TE waste-M exhibited lower overpotential and a smaller Tafel slope than TE waste-BM and stable operation for 18 h with negligible current decay, attributed to the accelerated charge transfer, fast water dissociation steps and rapid hydrogen adsorption in TE waste-M, originating from the presence of a BiSbTe₃/ZnTe heterostructure and defect-enriched interfaces. First-principles calculations based on density functional theory (DFT) revealed that the strengthened bonding states of the heterostructures near the Fermi level aid in enhancing the HER activity of the BiSbTe₃/ZnTe heterostructure. This work simultaneously integrates waste management with green hydrogen production by offering an economically viable, scalable and low-carbon approach to HER catalysts.