Laser-Induced Graphitic Carbon with Ultrasmall Nickel Nanoparticles for Efficient Overall Water Splitting

Metal nanoparticles encapsulated in graphitic carbon can show high catalytic efficiency and stability, yet the production method remains improved. Herein, it is demonstrated that a Ni-based metal–organic framework EG-MOF-74(Ni)] can be rapidly transformed into ultrasmall Ni-nanoparticles with different sizes (4–11 nm) encapsulated in graphitic carbon via the laser-scribing method. The synthesized sample shows the best electrocatalytic performances with excellent stability in alkaline electrolyte for oxygen/hydrogen evolution reactions with overpotentials of 0.35/0.18 V at a current density of 10 mA cm^?2 when the Ni particle size is ≈6 nm. This is because of its well-developed micro/mesoporous structure, high electronic transport, and large electrochemical active surface area. An electrolyzer with Ni-nanoparticles encapsulated in the graphitic carbon shows a current density of 10 mA cm^?2 at a voltage of 1.6 V, which is comparable to the Pt/C and RuO₂ counterparts. The laser-based synthesis can serve as a powerful tool for the size-controlled synthesis of various catalysts out of MOFs.