Voltage- and pH-driven evolution of multi-pathway C-C coupling in CO2 electroreduction on copper.

Reducing CO2 into high-energy-density multi-carbon products is critical for addressing climate and energy challenges, with copper being the only metal capable of catalyzing this transformation. However, the fundamental mechanisms of C-C coupling on copper surfaces remain elusive. Previous models have primarily focused on *OC-CO and *OC-COH coupling steps, lacking the dynamic and comprehensive perspective towards the whole system. Addressing this gap, our microkinetic modeling systematically investigates how environmental factors modulate multi-pathway C-C coupling mechanisms. We demonstrate that voltage and pH do not simply enhance a single coupling step but dynamically regulate the accessibility and competition among multiple coupling routes, consistent with previous experimental research. These findings establish a more comprehensive understanding of C-C coupling under realistic electrochemical conditions, offering new guidance for the rational design and optimization of copper-based catalysts for sustainable multi-carbon product synthesis.