Investigation of morphology, electronic, and chemical structure of lignin-based graphene by XPEEM

Purpose and goal:

The main objective of this project is to understand the morphology, electronic, and chemical structures of bio-based graphene made from lignin using soft X-ray photoemission electron microscopy (XPEEM), and low energy electron microscopy (LEEM) at MAXPEEM beamline, MAX IV. We aim to identify structure characteristics linked to critical parameters, e.g., temperature and lignin source, which will help the company to broaden its application market.

Expected results and effects:

The analysis technique allows the detection of the graphene’s spatially resolved empty orbital structures, which is closely related to the local chemical structure. The XPEEM image complements lab-based scanning electron microscopy and scanning Raman spectro-microscopy with element-specified chemical sensitivity, e.g., targeted on C and O respectively, and high spatial resolution.

The results allow the company Bright Day Graphene to better understand how the processing parameters modify the chemical structure of their bio-based graphene products. Approach and implementation:

The company Bright Day Graphene produced lignin-based graphene using the lignin precursor produced and refined by RISE. The bio-based graphene samples were dispersed in acetone solutions, drop-casted on Au-coated Silicon chips, and analyzed at the MAXPEEM beamline maintained under an ultrahigh vacuum. By measuring the C and O K-edge X-ray absorption signal with spatial resolutions, we were able to map the chemical states distribution and correlated it to the processing conditions. In total, six specimens prepared via different processing had been characterized.