High hydrogen coverage on graphene via low temperature plasma with applied magnetic fields

The chemical functionalization of two-dimensional materials is an effective method for tailoring their chemical and electronic properties with encouraging applications in energy, catalysis, and electronics. One exemplary 2D material with remarkable properties, graphene, can be exploited for hydrogen storage and large on/off ratio devices by hydrogen termination. In this work, we describe a promising plasmabased method to provide high hydrogen coverage on graphene. A low pressure (similar to 10 mtorr) discharge generates a fine-tunable low-temperature hydrogen-rich plasma in the applied radial electric and axial magnetic fields. Post-run characterization of these samples using Raman spectroscopy and X-ray photoelectron spectroscopy demonstrates a higher hydrogen coverage, 35.8%, than the previously reported results using plasmas. Plasma measurements indicate that with the applied magnetic field, the density of hydrogen atoms can be more than 10 times larger than the density without the magnetic field. With the applied electric field directed away from the graphene substrate, the flux of plasma ions towards this substrate and the ion energy are insufficient to cause measurable damage to the treated 2D material. The low damage allows a relatively long treatment time of the graphene samples that contributes to the high coverage obtained in these experiments. (c) 2021 Elsevier Ltd. All rights reserved.

Automated summary

Chemical functionalization of two-dimensional materials, such as graphene, is an effective method for tailoring their properties, with potential applications in energy, catalysis, and electronics. A promising plasma-based method has been developed to provide high hydrogen coverage on graphene, demonstrating higher coverage than previous results and showing potential for diverse applications. The use of radial electric and axial magnetic fields in low-pressure discharge generates a fine-tunable low-temperature hydrogen-rich plasma with enhanced hydrogen density, paving the way for further research and technological advancements in this field.