N-Doped Cu/Cuxo/C Foam Catalyst Having Multi-Crystaline Derived from Alkaline N-Coordinated HKUST-1/CMC for Enhanced 4-Nitrophenol Reduction

N-doped Cu/Cu_xO/C foam catalysts with multi-crystalline are synthesized from N-coordinated HKUST-1/cellulose for enhanced 4-nitrophenol reduction. Effect of N content and basicity on Cu morphology, crystal lattice and size, component dispersion and oxidation states in catalysts are systematically investigated. The facility of nano-catalyst synthesis from crystalline powders to robust morphology based foamed catalysts strategy is confirmed crediting to its simplicity and industrial applications. It is revealed that (1) graphitic nano-structure has been detected from carbonized N-doped HKUST-1 due to the catalysis of Cu sites towards C/N elements in HKUST-1; (2) alkaline N-doping inhibits the crystal growth of Cu species, resulting in crystal size of 3-5 nm in porous catalyst samples; (3) DFT simulation verifies that N doping will lower HOMO and LUMO energies of Cu-BTC in various degree It significantly restrains a complete reduction of Cu ions in HKUST-1, and facilitates the formation of a multi-crystalline Cu/Cu_xO/C based from HKUST-1 calcination; (4) amount of Cu₂O in N-doped Cu/Cu_xO/C gradually increases with the enhanced alkaline strength and content of the N dopant in HKUST-1. Catalysis performance exhibits that our designed N-doped Cu/Cu_xO/C based from HKUST-1s show much higher fast catalysis kinetics and better recycle performance on par with the start-of-the-art catalysts. Among which, melamine-doped Cu/Cu_xO/C foam catalyst exhibits the most outstanding activity in the reduction of 4-nitrophenol with a kinetic rate of 1.75 min^-1, 21 times faster comparing with bare Cu/C catalyst based on pristine HKUST-1, demonstrating the critical contribution of the foamed morphology and multi-crystalline of Cu/Cu_xO/C to the outstanding activity and recycle performance.