From surface transfer doping to nitrogen-assisted charging in hydrogenated nanodiamonds

Hydrogenated nanodiamonds exhibit unusual surface polarity, positive ζ-potential, and strong interactions with water and small molecules, yet the origin of these effects remains debated due to the intertwined roles of lattice disorder and nitrogen incorporation. In particular, detonation and HPHT nanodiamonds are often discussed interchangeably despite fundamental differences in structure and impurity content. Here, we address this ambiguity by introducing low-nitrogen detonation nanodiamonds with a defective structure comparable to conventional DNDs, enabling separation of nitrogen-related and defect-driven effects. Using hydrogen annealing up to 1300 °C combined with spectroscopic, electrokinetic, and thermogravimetric analyses, we examine how hydrogen termination, nitrogen content, and structural quality jointly influence surface charging, hydration, and CO 2 interaction. The study establishes a unified framework linking work function, ζ-potential, vibrational signatures, and interfacial reactivity in hydrogenated nanodiamonds, providing a basis for interpreting their behavior in charge-transfer and environmental applications.