Thermal Solid–Solid Transformation Synthesis of Zinc Anchored in Hierarchical Porous N-Doped Carbon for Efficient CO₂ Applications

A facile method was developed from solid precursors to obtain zinc anchored in a nitrogen-doped carbon matrix (Zn-NCx) via the solid-solid thermal (SST) route. The applied method, to synthesize Zn-NCx, was completed under single-step and solvent-free conditions. Regarding the synthesis mechanism, the zeolitic-imidazole framework (ZIF-8) was first fabricated from solid mixed precursors at a low temperature of the SST process. In a continuous mode, the fabricated ZIF-8 was sacrificed at a high temperature of the SST process to obtain Zn-NCx. Detailed characterization was performed to investigate the solid-solid transformation of precursors during the SST route. This characterization confirmed that Zn-NCx consists of zinc anchored in the nitrogen-doped carbon matrix. Also, due to the high porosity and N-functionalization, Zn-NCx exhibited excellent adsorption properties for CO2 and was helpful in CO2/CH4 separation. Furthermore, the chemical properties in hierarchical porous Zn-NCx were demonstrated to act as a catalyst for CO2 fixation. Interestingly, since the current method (SST) is solvent-free, this is a promising environmental route. The procedure has the potential for upscaling, revealing vast prospect for applications based on these carbon materials.