Layer-by-Layer Modified Screen-Printed Carbon Electrode using Zirconium-Based Metal–Organic Framework, Quantum Dots, and Graphene for Enhanced Oxygen Evolution Reaction Performance

Electrocatalysts for the oxygen evolution reaction (OER) must be effective, inexpensive, and long-lasting if electrochemical water splitting technologies are to advance. In this study, screen-printed electrodes containing ZIF-67—a zirconium-based metal–organic framework (Zr-MOF) composed of trimesic acid, carbon quantum dots (CQDs), and graphene nanoplatelets (GNPs)—were created using a layer-by-layer modification process. Increased number of active sites, increased surface area, and improved electron transport were demonstrated in structural and electrochemical testing of hybrid electrocatalyst systems. In comparison to reported electrodes, the ZIF/MOF/GNP-modified screen-printed carbon electrode (SPCE) performed significantly better at OER, with a reduced overpotential of 280 mV at 10 mA cm⁻² and a Tafel slope of 40 mV dec⁻¹. Electrochemical impedance spectroscopy (EIS) confirms a significant reduction in charge transfer resistance due to the improved interfacial conductivity. After 18 h of operation, the system displayed excellent performance with little drift, according to chromatopotentiometry testing. Because the MOF framework was made more conductive by the combined effects of conductive GNPs and CQDs, EIS revealed a reduction in charge transfer resistance. These findings suggest that a hybrid system consisting of ZIF, MOF, and GNP might be an effective electrocatalyst for cost-effective, scalable, and environmentally friendly water splitting applications. They additionally demonstrate that this SPCE-based layer modification method may be utilized for extensive, cost-effective water-splitting applications.