In the bulk state, the survey spectrum obtained from Xray photoelectron spectroscopy (XPS) confirms the presence of all constituent elements in Cu23 NC (Figure ). The high-resolution binding energy spectrum further reveals that Cu exists in the +1-oxidation state, while the thiolate ligands are in the -1-oxidation state (Figure ). Given the neutral charge state of the cluster, one Cu atom must be in the 0-oxidation state. However, distinguishing Cu(0) from Cu(I) in the XPS binding energy spectrum is not possible. This differentiation is achieved using X-ray excited Cu LMM auger electron spectroscopy (XAES), which shows peaks at 915.6 eV and 918.4 eV, corresponding to Cu(I) and Cu(0), respectively, in the Gaussian-Lorentzian band (Figure ). An additional Gaussian-Lorentzian band with a peak position at ~911 eV was considered to eliminate the effect of other orbital electrons on the XAES, which appeared as a shoulder peak (Figure ). To further verify the presence of an unpaired electron, electron paramagnetic resonance (EPR) spectroscopy was conducted at 77 K. The EPR spectrum exhibited an isotropic signal with a g-value of 2.07 (Figure ). This isotropic pattern indicates the symmetric positioning of the Cu(0) atom, suggesting it resides at the fused center, the only symmetric position within the cluster unit. Further validation comes from theoretical approximation supporting the presence of the Cu(0) atom at the fused center of the cluster by both spin density and partial atomic charge calculation. We have observed the highest spin density and least positive charge for the fused center of the cluster (Figure ). The Cu23 NC exhibits a monotonic decrease in the UV-vis absorbance spectrum in the solvent medium with a small shoulder peak ~ 410 nm resemblance with other previously obtained Cu-thiolate NC (Figure ). So, there is no such contribution of the Cu(0) center in the UV-vis spectrum. At room temperature we could not detect any luminescence property of it. As we described in the introduction section that Cu NCs have garnered significant attention as catalysts for electrochemical CO2RR due to their high reactivity and unique structural architecture, which can selectively tune product formation. In this work, we aim to explore the potential of a uniquely designed Cu23 NC as a catalyst for CO2RR. To perform the electrochemical measurements, a thin film electrode was fabricated using a spray coating technique. This involved depositing a slurry of the Cu23 NCs and carbon black (CB) onto a carbon paper substrate. It is crucial to maintain the geometric and electronic structure of the NCs during this loading process to preserve their electrocatalytic properties. The stability of the Cu23 NCs during this process was assessed using X-ray absorption fine structure (XAFS) spectroscopy. The X-ray absorption near-edge structure (XANES) spectra at the Cu K-edge for both the pristine Cu23 NC and the loaded catalysts (Cu23/CB) showed significant overlap, indicating no notable changes in their electronic states (Figure ). Both samples displayed a peak ~8992 eV, confirming the presence of a mixture of Cu(I) and Cu(0) species, as this peak lies between the characteristic energies of Cu(0) and Cu(I) species.