We immobilised SPy on the surface of Cu nanoparticles (NPs) through self-assembly from organic solution. Successful anchoring was initially confirmed using Fourier-transform infrared (FTIR) spectroscopy, which showed signals corresponding to the surface-bound ligand (Fig. ). X-ray photoelectron spectroscopy (XPS) was used to further verify SPy attachment (Figs. and, Table ). The N1s XPS spectrum showed three distinct environments corresponding to protonated and deprotonated forms of SPy, and the S2p spectrum showed signals arising from physisorbed thiol (164.3 eV) and covalently-bound thiolate (163.1 eV) sulfur environments, alongside small amounts of residual oxidised sulfur (168.2 & 169.4 eV), as expected for this type of immobilisation procedure. DFT calculations to determine the optimised conformation of SPy showed that the S preferentially binds two Cu atoms with the ring slightly tilted away from the Cu surface (Fig. ). We observed no obvious differences in morphology or size between unfunctionalised Cu and Cu-SPy, showing that the modification does not result in surface restructuration (Fig. ).(37) Gas diffusion electrodes (GDEs) were prepared by airbrushing a methanolic solution of ionomer (Nafion) and functionalised CuNPs onto PTFE membranes to form a porous network (approximately 10 µm thick) (Fig. ). A geometrical molecular loading of 15 nmol cm -2 was determined by UV-Vis spectroscopy after reductive desorption of SPy at -2.2 V vs. Ag/AgCl/KCl3.4M (Note S1).