A green blowing strategy toward massive synthesis of P, N, S-codoped carbon nanosheets incorporated with metal phosphides and the lithium storage application

We present a green and scalable chemical blowing strategy toward the mass production of two-dimensional (2D) P, N, S-codoped carbon nanosheets incorporated with CoP nanoparticles (CoP@PNS-CNS) through annealing a gel precursor. And the precursor is simply prepared via the gelation reaction among Co²⁺, L-cysteine (LC), and phytic acid (PA). It is noted that LC is a common amino acid in eggs, milk, and living organisms, and PA can be derived from plants or seeds, both of which are eco-friendly. The amino (-NH₂)/sulfhydryl (-SH) groups in LC and the phosphate groups (-H₂PO₄) in PA have dual functions in one go: they not only ensure the formation of the cross-linked gel precursor but also serve as N, S, and P sources for the doping of carbon nanosheets and phosphating process. To demonstrate their potential application, the resultant CoP@PNS-CNS is used as the anode material for reversible Li-ion storage. Owing to the presence of 2D PNS-CNS and uniformly dispersed CoP nanoparticles, CoP@PNS-CNS exhibits a high capacity of 595.3 mAh g⁻¹ at 100 mA g⁻¹, superior rate capability, and long-term cycling stability. Moreover, the specific capacity has high consistency with the theoretical value calculated from the density functional theory. This green and efficient chemical blowing technique is versatile and provides insights into the fruitful engineering of active composites at the nanoscales and macroscales to design phosphide-carbon hybrids.