The supporting information section of the article provides detailed experimental details and supplementary data for the study on the photoelectrochemical (PEC) conversion of solar CO₂ using atomically precise metal nanoclusters (Auₓ NCs) and MXene. The materials used, including various chemicals and powders, are sourced from reputable suppliers. The photoelectrochemical measurements were conducted using electrochemical workstations in a three-electrode quartz cell setup, with FTO glass coated with the samples serving as the working electrode. The zeta potential, UV-vis absorption spectra, FESEM images, XRD patterns, and other characterization techniques were employed to analyze the properties of the samples. Additional figures and tables provide visual and numerical data on the stability, chemical bonding, and electrochemical performance of the samples.The supporting information section of the article provides detailed experimental details and supplementary data for the study on the photoelectrochemical (PEC) conversion of solar CO₂ using atomically precise metal nanoclusters (Auₓ NCs) and MXene. The materials used, including various chemicals and powders, are sourced from reputable suppliers. The photoelectrochemical measurements were conducted using electrochemical workstations in a three-electrode quartz cell setup, with FTO glass coated with the samples serving as the working electrode. The zeta potential, UV-vis absorption spectra, FESEM images, XRD patterns, and other characterization techniques were employed to analyze the properties of the samples. Additional figures and tables provide visual and numerical data on the stability, chemical bonding, and electrochemical performance of the samples.