Ru single atoms and nanoparticles on carbon nanotubes as multifunctional catalysts

• Published in: Dalton transactions : an international journal of inorganic chemistry 2020-08, Vol.49 (29), p.125-126
• Main Authors: Fernandes, Diana M, Rocha, Mariana, Rivera-Cárcamo, Camila, Serp, Philippe, Freire, Cristina
• Format: Article
• Language: English
• Subjects: Carbon nanotubes; Catalysts; Catalytic activity; Chemical Sciences; Coordination chemistry; Histograms; Hydrogen peroxide; Nanoparticles; Nitrophenol; Oxygen evolution reactions; Oxygen reduction reactions; Rate constants; Reducing agents; Room temperature; Ruthenium; Size distribution; Stability tests
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/d0dt02096f

In the last decade we have witnessed increasing interest in the production of renewable energy and value-added chemicals through sustainable and low-cost technologies where catalysts play a crucial role. Herein, we report the application of a Ru/CNT material containing a mixture of Ru single atoms and Ru nanoparticles as a multifunctional catalyst for both the catalytic reduction of nitroarenes and the electrocatalytic oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). The catalytic activity of the Ru-CNT material was evaluated in the reduction of 4-nitrophenol (4-NP), 4-nitroaniline (4-NA) and 2-nitrophenol (2-NP) in the presence of sodium borohydride as a reducing agent at room temperature, showing high catalytic activity with normalized rate constants ( k nor ) of 19.0 × 10 3 , 57.7 × 10 3 and 16.6 × 10 3 min −1 mmol −1 respectively. Furthermore, the catalyst could be reused in at least 10 cycles without catalytic activity loss, confirming the high stability and robustness of the material. The Ru/CNT material also showed good ORR electrocatalytic activity in alkaline medium with E onset of 0.76 V vs. RHE, a diffusion-limited current density of 3.89 mA cm −2 and ñ O 2 of 3.3. In addition, Ru/CNT was remarkably insensitive to methanol with a current retention of 93% (51% for Pt/C) and competitive electrochemical stability of 80% after 20 000 s. Moreover, Ru/CNT was active for the OER with j max = 29.5 mA cm −2 at E = 1.86 V vs. RHE, η 10 = 0.50 V and good stability ( η 10 changed to 0.01 V and j max only decreased by 12% after 500 cycles). We report the application of Ru/CNT for the catalytic reduction of nitroarenes and the electrocatalytic oxygen reactions (ORR/OER).