Room temperature 3D carbon microprinting.

Manufacturing custom three-dimensional (3D) carbon functional materials is of utmost importance for applications ranging from electronics and energy devices to medicine, and beyond. In lieu of viable eco-friendly synthesis pathways, conventional methods of carbon growth involve energy-intensive processes with inherent limitations of substrate compatibility. The yearning to produce complex structures, with ultra-high aspect ratios, further impedes the quest for eco-friendly and scalable paths toward 3D carbon-based materials patterning. Here, we demonstrate a facile process for carbon 3D printing at room temperature, using low-power visible light and a metal-free catalyst. Within seconds to minutes, this one-step photocatalytic growth yields rod-shaped microstructures with aspect ratios up to ~500 and diameters below 10 µm. The approach enables the rapid patterning of centimeter-size arrays of rods with tunable height and pitch, and of custom complex 3D structures. The patterned structures exhibit appealing luminescence properties and ohmic behavior, with great potential for optoelectronics and sensing applications, including those interfacing with biological systems.

Locally strained hexagonal boron nitride nanosheets quantified by nanoscale infrared spectroscopy.

Defect engineering in two-dimensional materials expands the realm of their applications in catalysis, nanoelectronics, sensing, and beyond. As limited tools are available to explore nanoscale functional properties in non-vacuum environments, theoretical modeling provides some invaluable insight into the effect of local deformations to deepen the understanding of experimental signals acquired by nanoscale chemical imaging. We demonstrate the controlled creation of nanoscale strained defects in hexagonal boron nitride (h-BN) using atomic force microscopy and infrared (IR) light under an inert environment. Nanoscale IR spectroscopy reveals the broadening of the in-plane phonon (E1u) mode of h-BN during defect formation while density functional theory-based calculations and molecular dynamics provide quantification of the tensile and compressive strain in the deformation.

Enhancing Infrared Light-Matter Interaction for Deterministic and Tunable Nanomachining of Hexagonal Boron Nitride.

Tailoring two-dimensional (2D) materials functionalities is closely intertwined with defect engineering. Conventional methods do not offer the necessary control to locally introduce and study defects in 2D materials, especially in non-vacuum environments. Here, an infrared pulsed laser focused under the metallic tip of an atomic force microscope cantilever is used to create nanoscale defects in hexagonal boron nitride (h-BN) and to subsequently investigate the induced lattice distortions by means of nanoscale infrared (nano-IR) spectroscopy. The effects of incoming light power, exposure time, and environmental conditions on the defected regions are considered. Nano-IR spectra complement the morphology maps by revealing changes in lattice vibrations that distinguish the defects formed under various environments. This work introduces versatile experimental avenues to trigger and probe local reactions that functionalize 2D materials through defect creation with a higher level of precision for applications in sensing, catalysis, optoelectronics, quantum computing, and beyond.