Data supporting the publication findings (data.zip) that can reproduce figures from the main text. In text file format: Dark field scattering spectra for phenyl diisocyanide (PDI) and Ni(tpyS)₂ NPoMs. Potential-dependent SERS spectra of PDI molecule displaying isocyanide group shifts, and extracted peak positions from NPoM and roughened Au. Cyclic voltammetry for Ni(tpyS)₂ in N₂ and CO₂ purged conditions and the corresponding SERS spectra and DFT calculated spectra. In (code.zip) we include: Python 3 files (.py) for earth mover's algorithm spectral matching and DFT calculated structures for Ni(tpyS)₂ throughout the CO₂ reduction cycle (.out and .log). HOMO and LUMO calculations for two structures are included as .cub files. Experimental spectra used for matching are included as .npy and .dat files.