Correlative surface analysis across different information depths of covalently functionalized Graphene oxide and Black phosphorus

Le résumé fourni par la source

Covalent functionalization of two-dimensional (2D) materials often produces layered structures where surface layers mask the underlying substrate for many surface-sensitive analytical techniques. However, it remains unclear how the measured signals obtained by surface-sensitive techniques of different information depths relate to the functional layer and the underlying substrate. Here, we present a correlative characterization strategy for covalently functionalized graphene oxide (GO) and black phosphorus (BP) sheets with complementary techniques of different information depths. The strategy is particularly well suited for layered materials and thin films, where depth-resolved information is more relevant compared to lateral resolution. Four model systems are investigated, comprising GO and BP functionalized either with small triazine derivatives or with larger biomolecules (bovine serum albumin and fucoidan). The materials are characterized by X-ray photoelectron spectroscopy (XPS), hard X-ray photoelectron spectroscopy (HAXPES), time-of-flight secondary ion mass spectrometry (ToF-SIMS), near-edge X-ray absorption fine structure spectroscopy (NEXAFS), and Raman spectroscopy. Small-molecule functionalization allows simultaneous detection of both the functional layer and the underlying substrate across the investigated techniques. In contrast, modification with macromolecules suppresses substrate-related signals in XPS and ToF-SIMS measurements, whereas HAXPES and Raman spectroscopy allow deeper analysis and detection of underlying 2D substrate. The presented approach provides a general strategy to interpret the results obtained from complementary surface-sensitive techniques and is broadly applicable to functionalized layered materials and thin films.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.