Shear-Assisted Compression Induced Diamane Formation in Hydrogenated Multilayer Graphene

One of the main challenges for the pressure-induced multilayer graphene to atomically thin diamond scale-up synthesis process is the requirement of high compressive pressures. Our previous studies revealed a reduction in graphene to diamane transformation stress upon shearing and fully hydrogenation separately, motivating current investigation on their combined effect on improving the synthesis conditions. We revealed that the transformation stress reduces by an order of magnitude upon the combined implementation of shear and hydrogenation. Our findings showed that a higher percentage of hydrogenation hinders the sp²to sp³ hybridization, which results in higher transformation stress due to the steric effect in the presence of shear. The comparative study of transformation stress between shear and no shear conditions proves the effect of shear on this particular phase transformation. Using machine learning models, we found that although shear and layer number significantly affect the graphene to diamond transformation stress, transformation stress is a strong function of hydrogenation amount and temperature. The presented results guide the future experimental synthesis of multilayer diamane structures.