Laser-Induced Graphene from Wood Impregnated with Metal Salts and Use in Electrocatalysis

The hybridization of graphene with other inorganic nanostructures has endowed graphene with enhanced and varied functionalities. Here we demonstrate a facile and improved approach to convert biodegradable cedar wood into graphene embedded with various metal nanocrystals (cedar-LIG-M, LIG is laser-induced graphene, M = Cu, Co, Ni, Fe, NiFe) by sonication-assisted soaking and one-step CO₂ laser scribing. Organic biomass was transformed to hierarchical porous graphene via laser induction, whereas metal salts were reduced to elemental metals simultaneously by the carbothermal reaction and reducing atmosphere generated during the lignocellulose decomposition. The as-prepared cedar-LIG-M possesses an ordered porous structure, good conductivity, unique ferromagnetic behavior and excellent electrochemical catalytic performance. As a demonstration, the cedar-LIG-NiFe electrode has a low overpotential of 296 mV at a current density of 10 mA cm^-2 for oxygen evolution reactions. The performance of the electrode continued to improve at the initial testing stage due to the in situ activation as a result of the increased oxidation states of nickel and iron during electrochemical oxygen evolution. In addition, the cedar-LIG-NiFe could also serve as an electromagnetic interference shielding material with shielding effectiveness up to 54 dB. The simplicity and versatility of this technique provides a route for the synthesis of various carbon-based hybrid materials with potential applications of the products in many different fields, such as energy storage, electrocatalysis, electromagnetic interference shielding, and water treatment.