A contact-electro-catalysis process for producing reactive oxygen species by ball milling of triboelectric materials

Abstract Ball milling is a representative mechanochemical strategy that uses the mechanical agitation-induced effects, defects, or extreme conditions to activate substrates. Here, we demonstrate that ball grinding could bring about contact-electro-catalysis (CEC) by using inert and conventional triboelectric materials. Exemplified by a liquid-assisted-grinding setup involving polytetrafluoroethylene (PTFE), reactive oxygen species (ROS) are produced, despite PTFE being generally considered as catalytically inert. The formation of ROS occurs with various polymers, such as polydimethylsiloxane (PDMS) and polypropylene (PP), and the amount of generated ROS aligns well with the polymers’ contact-electrification abilities. It is suggested that mechanical collision not only maximizes the overlap in electron wave functions across the interface, but also excites phonons that provide the energy for electron transition. We expect the utilization of triboelectric materials and their derived CEC could lead to a field of ball milling-assisted mechanochemistry using any universal triboelectric materials under mild conditions

Fabrication of Magnetic Core–Shell CZ/Fe₃O₄ Catalysts for Catalytic CO-SCR

Transition metal catalysts exhibit great promise for application in the field of CO-SCR owing to their exceptional performance and cost effectiveness. The metal oxides generated by traditional synthesis methods often have irregular morphology and small pore sizes, leading to the problems of uneven loading and difficult recycling. Hence, we utilized a two-step hydrothermal methodology to fabricate CexZr1–xO2/Fe3O4 hollow core–shell structured nanocomposites with a high specific surface area and robust paramagnetic properties. These nanostructures exhibit exceptional efficacy in simultaneous elimination of NO and CO. Catalysts with varying molar ratios of Ce/Zr were introduced, resulting in diverse Ce3+/Ce4+ and Fe2+/Fe3+ ratios, abundant oxygen vacancies, and exceptional reducibility, in which the Ce0.7Zr0.3O2/Fe3O4 catalyst achieves 100% NO conversion at 300 °C because it has a large specific surface area, abundant oxygen vacancies, and active sites. In addition, in situ DRIFTS analysis of the samples before and after the magnetization treatment showed that the magnetic field promoted NO adsorption