Bimetallic Cu–Zn Prussian blue analogue nanoparticles for enhanced oxygen evolution reaction

The quest for sustainable energy sources has led to the exploration of efficient electrochemical water splitting technologies. Oxygen evolution reaction (OER), a crucial process in water splitting, plays a pivotal role in the production of clean hydrogen fuel. Recently, metal hexacyanocobaltate (MHCCs) have garnered attention as OER catalysts because of their distinctive open structure, which allows for the customization of their electronic and catalytic features. Nonetheless, single-metal MHCCs, such as CuHCC and ZnHCC, have inherent shortcomings such as low stability under harsh alkaline conditions, low conductivity, and high OER overpotential, which limit their OER applications. To address these drawbacks, the synthesis and utilization of bimetallic Cu–Zn hexacyanocobaltate nanoparticles have emerged as a promising avenue for enhancing OER efficiency. The incorporation of both elements results in a catalyst with enhanced electrocatalytic activity, improved stability, and optimized OER kinetics compared to those of their individual counterparts. In this study, bimetallic Cu–Zn hexacyanocobaltate (Cu_xZn_3−xHCC) nanoparticles with different Cu to Zn ratios were synthesized using a simple hydrothermal process, and their OER catalytic activity was studied. The Cu_xZn_3−xHCC nanoparticles exhibited a lower OER overpotential and long-term OER activity with minimal changes in overpotential. Moreover, the graphite||Cu_xZn_3−xHCC couple requires a cell voltage of only 1.831 V to drive the alkali-electrolyser at the current density of 10 mA cm⁻², proving practical application of the synthesized bimetallic MHCC in the energy conversion field.