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.