NiFe Nanoparticle Encapsulated into Wood Carbon for Efficient Oxygen Evolution: Effect of Wood Delignification

Abstract

Opportunities for wood in the field of electrocatalysis can be increased by delignification because it etches cell walls and increases pore numbers. Herein, electrocatalysts were prepared by delignifying natural wood to varying degrees, to which NiFe-active nanoparticles were then adsorbed. The effect of delignification on the oxygen evolution of wood-based electrocatalytic materials was elucidated. The oxygen evolution performance of the corresponding electrocatalyst was improved by increasing the degree of wood delignification. This is due to the improved specific surface area, porosity, hydrophilicity, and air repellency of the wood substrate after delignification. Delignified wood exposed abundant hydroxyl groups and adsorbed a large number of NiFe-active nanoparticles. The catalyst prepared on the most delignified wood substrate (NiFe/DWC-3) exhibited the best oxygen evolution performance, with an overpotential of only 262 mV at a current density of 100 mA cm–2, which is lower than that of NiFe/WC prepared on a natural wood substrate (372 mV). In addition, the overpotential of NiFe/DWC-3 increased by only 3.35% after the 60 h long-term testing, indicating favorable stability. This strategy may be particularly beneficial for designing high-performance wood-derived electrocatalysts using wood substrates with maximum delignification.