Exploiting the synergistic effect of Ag and Cu doping in eco-friendly quantum dots for boosted photoelectrochemical performance

Abstract

Manipulating the intrinsic properties of colloidal quantum dots (QDs) offers a promising pathway to achieve efficient solar-driven photoelectrochemical (PEC) hydrogen evolution toward carbon neutrality. In this work, a novel environmentally benign light-harvesting material of silver (Ag) and copper (Cu) co-doped zinc–indium–sulfide/zinc selenide (Zn–In–S/ZnSe) core/shell QDs was developed, wherein the co-dopants establish a synergistic charge transfer pathway of Ag-mediated hole migration to Cu acceptor states in the QDs, thus creating a stabilized donor–acceptor configuration for enhanced charge carrier extraction. As a consequence, the PEC devices fabricated using the optimized Ag, Cu-ZIS/ZnSe QDs delivered a maximum photocurrent density of 8.9 mA cm⁻² at 0.6 V versus the reversible hydrogen electrode (vs. RHE) under 1 sun AM 1.5G illumination (100 mW cm⁻²), representing a 6.4-fold improvement over the undoped ZIS/ZnSe QD PEC systems. Moreover, the fabricated Ag, Cu-ZIS/ZnSe QD-based PEC device exhibited a hydrogen production rate of 105.8 μmol cm⁻² h⁻¹ with a faradaic efficiency (FE) of 72.4%, which is 8.5 times higher than the control device based on the undoped QDs. Our work presents a synergistic dopant engineering technique to optimize the charge kinetics of eco-friendly QDs for highly efficient PEC applications, showing great potential for constructing environment-friendly, low-cost and high-efficiency solar energy conversion systems.