Nickel Quantum Dots Anchored in Biomass-Derived Nitrogen-Doped Carbon as Bifunctional Electrocatalysts for Overall Water Splitting

Quantum dots (QD), mixed with carbon materials, have gained increasing interest in the last few years as electrocatalysts due to their outstanding properties, such as excellent catalytic activity and good thermodynamic stabilities. However, most QD-carbon hybrids show lower catalytic activities than that theoretically predicted due to the aggregation of the QD-carbon nanostructures during processing. Herein, biomass is used as a carbon source to prepare QD carbon nanostructures (Ni@CN) to address the aforementioned issue. The cells walls and membranes in the biomass materials are usually rich in sites that could regulate the deposition and growth of Ni from a salt precursor by a simple solution impregnation method. Due to the abundance of the seeding sits and the limited supply of Ni⁺, the Ni particles size is restricted to the QD level with 3–4 nm. The formed Ni compounds QD are strongly linked to the cells walls and membranes, which could be maintained after subsequent heat treatment. The prepared 3D architecture has high catalytic activity, large surface area, strong physical integration, and rapid charge transfer capability, which collectively enhances the performance toward oxygen evolution reaction and hydrogen evolution reaction, opening the door to empower the next-generation green fuel conversion for carbon neutral.