XPS spectra of nanocrystalline diamond films with nitrogen incorporation and hydrogen plasma exposure, acquired by monochromatic Al <i>Kα</i> x-ray source

Diamond is a wide bandgap material with outstanding structural and electronic properties, making it a promising candidate for applications in radiation detection, energy conversion, and electrochemistry. Among its characteristics, the electronic behavior of the surface plays a pivotal role. Hydrogen termination can enable efficient electron emission, whereas the incorporation of nitrogen during chemical vapor deposition (CVD) growth modifies the defect structure and electrical conductivity. Such effects are particularly relevant for electrochemical processes, where emitted electrons can become solvated in aqueous environments, acting as powerful reducing agents. In this study, we investigate CVD nanocrystalline diamond films deposited on polycrystalline diamond plates, focusing on the influence of nitrogen incorporation and post-growth hydrogen plasma treatment on their properties. Through x-ray photoelectron spectroscopy (XPS) analysis, we assess material quality and chemical states of the various C, O, and N moieties present in the target samples. Our findings may provide new insights into how surface chemistry and defect engineering control the functional response of diamond in technologically relevant environments.