Scalable Ni-Based Diffusion Synthesis of Highly Graphitic Nanointerlaced and Photopatternable Material with Fast Charge Transfer Kinetics

Graphitic and nanostructured carbon materials exhibit exceptional properties, including high electrical conductivity and chemical stability, yet their integration into microdevices remains challenging due to costly, low-yield production methods. Carbon-MEMS (C-MEMS) technology offers a scalable alternative for fabricating carbon microdevices, though it typically yields amorphous/glassy carbon with limited conductivity. Here, we bridge this gap with a scalable method for synthesizing highly conductive graphitic micropatterns. Our approach combines electrospinning of a photosensitive SU-8/MWCNT composite with pyrolysis and catalytic graphitization using a Ni film. Raman spectroscopy confirms increased graphitization (ID/IG = 0.3 vs 0.92 for pyrolytic carbon), and HRTEM analysis reveals numerous graphitic domains with parallel lattices exhibiting an interlayer distance of 3.46–3.59 Å. These observations are consistent with the substantial decrease in the ID/IG ratio and the corresponding increase in crystallite size (La) estimated by Raman spectroscopy, confirming the evolution of disordered carbon toward a long-range preferred orientation. This structural transformation is promoted by the Ni-based diffusion mechanism specific to our porous architecture. The process results in carbon nanofiber mats with enhanced electrical conductivity (CI95% [615.0, 824.2] S/m), a significant improvement over pyrolytic mats from the same composite (CI95% [4638.1, 5625.9] S/m). Electrochemically, the material exhibits superior charge-transfer kinetics (k° = 0.064 cm/s), outperforming some conventional carbons. Our investigations reveal that the inclusion of MWCNTs reduces porosity, thereby increasing conductivity by 3 orders of magnitude, which allows for the surface area and electron-transfer tuning. Furthermore, our Ni-based diffusion synthesis enables the direct integration of micropatterned, nanointerlaced graphitic devices into silicon substrates, eliminating transfer steps or the need for mechanical treatment while enabling complex geometries. In summary, this work provides a large-scalable route for the next generation of high-performance graphitic devices with broad applicability in miniaturized sensors and energy systems.