Nanoarchitectonics for optimization of a Ti/Au-IrOx electrode for enhanced catalytic performance pertinent to hydrogen evolution reaction

Catalytically driven electrochemical hydrogen evolution reaction (HER) holds immense promise for meeting renewable energy demands. In this study, we have reported highly efficient HER catalyst utilizing a novel electrode composed of titanium (Ti) sheet with gold and iridium oxide (Ti/Au-IrOx), compared to a conventional Pt electrode. The fabrication process involved anodizing a Ti strip to form a TiO2 film, onto which Au and IrOx particles were sequentially deposited, followed by cathodic and anodic reactions, respectively. The resulting Ti/ TiO2/Au-IrOx electrode exhibited remarkable efficiency in electrochemical HER, significantly reducing the overpotential. Notably, the catalytic onset potential was recorded at -0.10 V, markedly lower than those observed for Ti, Au, and Au-IrOx electrodes individually. This improvement can be attributed to an increase in the catalytic surface area along with a synergistic effect between the TiO2 metal sheet and the electronic state of Au, which facilitates the adsorption of hydrogen molecules onto the catalytic surface. Furthermore, the presence of IrOx supports the redox counter-reaction, enhancing overall electrochemical conversion kinetics. Electrokinetic parameters such as turnover frequency (TOF), Tafel slope, and exchange current density (jk) were calculated as 0.334 s-1, 64 mV dec- 1, and 0.12 mA cm-2, respectively, outperforming other experimental electrodes in this study and approaching values comparable to those of the Pt electrode (0.354 s-1, 36 mV dec- 1, and 1.13 mA cm-2, respectively). Additionally, the Ti/TiO2/Au-IrOx electrode exhibited lower resistance for charge transfer (Rct) during HER (0.072 k Omega) compared to other electrodes evaluated. These findings underscore the Ti/ TiO2/Au-IrOx electrode's potential as a highly efficient catalyst for HER under acidic conditions, offering insights into the intricate mechanisms driving catalytic enhancements beyond mere surface area augmentation.