We employ operando surface-enhanced Raman scattering (SERS) empowered by density functional theory (DFT) simulations to resolve the long-standing controversy about the first step of the CO2 electroreduction to fuels in aqueous electrolytes on copper. The SERS spectra are measured for the first time on an operating Cu catalyst. Using this advanced methodology, we reveal that the first intermediate of the CO2 conversion to formate on Cu is carboxylate anion *CO2- which is coordinated to the surface with one of its C-O bonds. The character of the *CO2- stabilization can explain its formation on a negatively charged surface and is critical for the chemical versatility of *CO2- (its capacity to be transformed to either carbon monoxide or formate). These results provide new insights into the CO2 electroreduction mechanism and selectivity.

The origin of the elusive first intermediate of CO2 electroreduction

256th National Meeting (2018)

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