Direct Laser Printing of 3D Porous Ni(OH)2/NiO Microarchitectures via Confined Interfacial Nucleation.

Transition-metal hydroxides and oxides are widely used in optoelectronic and electrochemical devices, yet precise control over their three-dimensional (3D) microarchitecture and morphology remains a major challenge for microscale device fabrication. Here, we report a laser-confined interfacial nucleation and hierarchical growth (LCING) strategy that enables direct laser printing of Ni(OH)2/NiO microarchitectures with high spatial resolution and programmable porous structures. The localized photothermal field drives interfacial nucleation and hierarchical growth, allowing conformal integration of hydroxide microstructures and flexible construction of complex 3D geometries. We further elucidate the coupled mechanisms of mass transport, heat transfer, and reaction kinetics governing the LCING process. By rationally tuning laser printing parameters, the morphology and porosity of the resulting microstructures can be precisely controlled. The printed Ni(OH)2/NiO microdevices enable high-resolution structural color patterning and enhanced sensing performance, with the 3D porous Ni(OH)2/NiO architectures showing improved gas-sensing responses compared with lower-dimensional and nonporous counterparts. This work presents a versatile and programmable approach for high-precision manufacturing of functional metal-oxide microdevices.