Ni-doped 3D-printed honeycomb carbon microlattices: Sustainable fabrication and functionalization of microarchitected carbon.

We developed composite photoresins for sustainable production of microarchitected carbon electrodes via stereolithography (SLA) 3D printing. The composite resins contain 20-25 mass% water that decreases the amount of organic waste. After printing, the scaffolds were pyrolyzed into honeycomb carbon microlattices (hCMLs) at 1,000°C in vacuum. hCMLs show reduced density as the water content increases, inferring subnanoscale structural changes within the constituent carbon. Ni added to photoresin thrusts graphitization at 1,000°C so reduces thermal energy conventional graphitization requires, especially when water delivers individual Ni ions. The homogeneously dispersed Ni ions, in contrast to Ni nanoparticles that aggregate, interconnected graphitized zones in hCMLs to lower electrical resistivity by ∼50%. The Ni-doped hCMLs readily serve as a bifunctional electrocatalyst for water splitting, inspiring design of functional microarchitected carbon composites. Our results can reduce waste and save energy in fabricating carbon microarchitectures, benefitting a wide range of electrical, electrochemical and other applications.