Cu single-atoms supported on molten salt-derived N-doped nanocarbons: A highly efficient catalyst for 4-nitrophenol reduction

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Batista, Walker Vinicius Ferreira do Carmo ; Cruz, Tais Santos ; Ferrari, Jefferson Luis ; Taborda, Nestor Cifuentes ; Pereira, Fabiano Vargas ; Gabriel Filho, Jose Balena ; Torres, Herick Ribeiro ; de Lima, Guilherme Ferreira ; Santos, Dalva Ester Costa Ferreira ; Noleto, Luis Fernando Guimaraes ; Teixeira, Ivo Freitas ; de Mesquita, Joao Paulo

• Document type: Journal article
• Source: Applied Surface Science; v. 708, p. 14-pg., 2025-11-01.

Abstract

In this work, we report the synthesis of a high-performance single-atom catalyst (SAC) for the reduction of nitrophenol employing NaBH4 under ambient conditions. A simple and straightforward molten salt-based strategy was employed to create negatively charged nitrogen- and oxygen-containing functional groups, capable of anchoring and stabilizing copper ions within the aromatic structure. This approach led to the development of a novel SAC consisting of Cu(I)/Cu(II) supported on nitrogen-doped carbon synthesized at different temperatures. EDS mapping results revealed high copper dispersion on the support surface, STEMHAADF, and EPR measurements confirmed the presence of Cu single-atoms. The catalysts demonstrated high catalytic activity under ambient conditions, with NaBH4 (TOF 846.5 h- 1) as a reducing agent. In addition to their high catalytic activity, the catalyst achieved conversion and selectivity rates above 90 % within 10 min, along with remarkable reusability over ten cycles, maintaining its activity. DFT calculations reveal that undercoordinated copper centres, particularly tri- and bi-coordinated sites, exhibit enhanced ability to adsorb and activate molecular hydrogen. These findings highlight an efficient and sustainable strategy for designing nonprecious metal SACs, offering promising prospects for catalytic applications in selective reduction reactions. (AU)

• FAPESP's process: 21/12394-0 - Sustainable synthetic methods employing catalysis, benign solvents, safer reagents, and bio-renewable feedstock
• Grantee: Arlene Gonçalves Corrêa
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 23/10329-1 - Production of value-added organic compounds (C2+) through the dry electrochemical reform of CH4 in supercritical CO2.
• Grantee: José Balena Gabriel Filho
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 21/11162-8 - Multi-user equipment approved in grant 2020/14741-6: GC-MS/FID/TCD (2 injetores+Loop+Sistema valvulado)
• Grantee: Ivo Freitas Teixeira
• Support Opportunities: Multi-user Equipment Program
• FAPESP's process: 22/14652-9 - Photoreduction reactions to sustainable production of chemical commodities: a solar to chemical strategy
• Grantee: Luis Fernando Guimarães Noleto
• Support Opportunities: Scholarships in Brazil - Doctorate
• FAPESP's process: 20/14741-6 - Graphitic carbon nitrides as platforms for single-atom photocatalysis: moving towards design principles for improved performance
• Grantee: Ivo Freitas Teixeira
• Support Opportunities: Research Grants - Young Investigators Grants