image: (a) Schematic illustration of solvent recycling fabrication of ZnNC; (b) SEM; (c) HAADF STEM image of the atomically dispersed ZnNC; (d) polarization curve (solid line) and H2O2 detection current (dashed line) at the ring electrode for initial and recycled ZnNC in 0.1 mol L-1 KOH; (e) the calculated selectivity. view more
Credit: ©Science China Press
Single-atom catalysts (SACs) are recently emerging as a new frontier in catalysis science. With maximum atom-utilization efficiency and unique properties, SACs exhibit great potential for enabling reasonable use of metal resources and achieving atomic economy. However, fabricating SACs and maintaining the metal centers as atomically dispersed sites under synthesis and catalysis conditions are challenging. Moreover, their syntheses always require the use of complex precursors and tedious procedure.
A recently published work by Sun et al., reported the use of formamide as both solvent and precursor, to dissolve Zn metal and then pyrolyze together to prepare Zn singe atom catalysts coordinated with nitrogen atoms in carbon matrix (ZnNC SACs). The formamide consists of abundant C and N species to coordinate with and fix the dissolved Zn atoms (resulted in Zn2+ cations), being beneficial to the preparation of ZnNC. Furthermore, residual formamide after one batch of experiment can be used again as solvent and precursor to dissolve Zn metals, until the formamide is totally consumed, highlighting the high atomic utilization efficiency of using formamide and pure metal as precursors in attempt to prepare SACs.
To verify the consistency of the reported recycle synthesis strategy towards ZnNC SACs, H2O2 production via two-electron transfer oxygen reduction reaction is used as a probe. The H2O2 selectivity on ZnNC can maintain over 75% (84% to 77%) throughout the whole four batches of recycle synthesis, with continuous working for 10,000s, verifying the consistency of the formamide-assisted recycle synthesis of ZnNC SACs.
The authors said “we believe the formamide as a non-toxic regent, with a high polarity, can be used to dissolved various pure metals, metal salts precursors, and the resulted solution can serve as a platform for green, easy synthesis of SACs. The strategy reported in this work will inspire the motivations from both the chemistry and materials communities”
http://engine.scichina.com/doi/10.1007/s40843-022-2054-5
Journal
Science China Materials