Boosting tribo-catalytic conversion of H ₂O and CO ₂ by Co ₃O ₄ nanoparticles through metallic coatings in reactors

In recent years, more and more metal oxides have been finding critical tribo-catalytic applications. Presently, we have explored the tribo-catalytic conversion of H₂O and CO₂ using Co₃O₄ nanoparticles and obtained some surprising results. In an as-received 150 mL glass reactor enclosed with 10 mL H₂O, 0.10 g Co₃O₄ nanoparticles, 1 atm CO₂, and a Teflon magnetic rotary disk, we observed the production of as much as 57.41 µmol/L of H₂, and 0.15 µmol/L of CH₄, 0.21 µmol/L of CO after 5 h magnetic stirring. Metallic coatings of Cu, Ni, SUS316, Ti, Nb, Mo, and W were further introduced on reactor bottoms separately. For those coatings of Ni, SUS316, Ti, and Nb, the reduction of CO₂ was dramatically enhanced and C₂₊ products of C₂H₆ and C₂H₄ were observed. Especially for Ti coating, the amounts of H₂ and CH₄ were increased by 2 and 26 times from those for the glass bottom, respectively, and the amounts of C₂H₆ and C₂H₄ were very impressive. Co₃O₄ nanoparticles were proven chemically stable under magnetic stirring in water, and hydroxyl radicals and superoxide radicals have been detected for Co₃O₄ nanoparticles under magnetic stirring through fluorescence spectroscopy and electron paramagnetic resonance spectroscopy analyses. These findings not only reveal an outstanding capability of Co₃O₄ to generate multicarbon products from H₂O and CO₂ through tribo-catalysis but also highlight a promising potential of tribo-catalysis as a whole to harness mechanical energy for addressing energy shortages and environmental pollution.