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The development of cost-effective electrocatalysts with a high electrochemically active surface area (ECSA) is essential for the efficient electrochemical reduction of CO2 (eCO2RR) into multicarbon products. Bimetallic catalysts present a promising approach due to their adjustable structure and synergistic effects, yet they remain insufficiently explored. In this study, we report the controlled electrodeposition of bimetallic Cu-In particles on a glassy carbon substrate from a 70:30 (v/v) acetonitrile-water solution containing 0.01 M CuCl2 and 0.01 M InCl3 at various temperatures. Analysis of the potentiostatic current transients using the Scharifker-Hills model revealed a temperature- and potential-dependent nucleation mechanism, involving a hybrid 2D instantaneous and 3D progressive growth. A transition from instantaneous to progressive nucleation was observed with an increase in deposition potential at 25 °C and 45 °C, while at 65 °C, the nucleation process was predominantly progressive. X-ray diffraction analysis identified the presence of Cu, In, Cu2O, In2O3, and CuIn alloy phases. Scanning electron microscopy analysis indicated the formation of temperature-controlled morphologies such as broccoli, wires, and dendrites. Pb underpotential deposition (Pb-UPD) and cyclic voltammetry demonstrated that the Cu-In broccoli morphology exhibited the highest ECSA and eCO2RR activity, with a current density of 41 mA cm−2 and a reduced Tafel slope of 168 mV dec−1. This study enhances our understanding of the influence of deposition parameters on structure-property relationships in bimetallic electrocatalysts for CO2 conversion.
Bekey et al. (Wed,) studied this question.