Enhanced Zn/ZnO Heterointerfaces via Pulsed-Potential Electrochemical Reconstruction for Highly Selective CO₂ Reduction

The electrochemical carbon dioxide reduction reaction (CO₂RR) demands advanced low-cost cathodes that can overcome the intrinsic scaling limits of single-phase metals. Accordingly, we report a pulsed-potential-based square wave voltammetry (SWV) strategy to reconstruct ZnO nanoparticles into metallic Zn nanoislands embedded on the ZnO wurtzite surface, generating an enhanced density of Zn/ZnO heterointerfaces. TEM/FFT and XPS analyses confirmed more finely discrete metallic Zn domains with a balanced Zn(0)/Zn(II) ratio for the SWV-ZnO electrocatalyst. At these heterojunctions, they preferentially stabilized the *COOH intermediate and weakened *H adsorption, thereby suppressing the competing hydrogen evolution reaction. The SWV-ZnO delivered a peak CO Faradaic efficiency of 90% with a CO partial current density of 5.3 mA/cm² at -1.05 V versus RHE in the H-cell, outperforming the pristine zinc nanoparticles and the previously reported potentiostatic reconstruction strategies (CA-ZnO). This work demonstrated that pulsed-potential electrochemical reconstruction offered a rapid and scalable route to engineer heterointerfaces, providing a practical blueprint for advancing sustainable CO₂-to-CO conversion technologies.