Redox mediators boost NO_x reduction via trade-off electron charges using a cube-shaped (cMn@rGO) catalyst; mechanism...

Gaseous pollutants like sulfur dioxide and nitrogen oxide(s) (SO₂, NO_x) have been increasing exponentially for the last two decades, which have had adverse effects on human health, aquatic life, and the environment. Recently, for air pollution taming, manganese/oxide (Mn/MnO) has become a very promising heterogeneous catalyst due to its environment-friendly, low-price, and remarkable catalytic abilities for toxic gases. In this work, cube-shaped Mn nanoparticles (cMn NPs) were decorated on the surface of reduced graphene oxide (rGO) by the solvothermal method. The resulting cMn@rGO composite was employed for electrochemical NO_x reduction. However, the microscopic (TEM/HRTEM) and structural analysis were utilised to investigate the morphology and characteristics of the cMn@rGO composite. This electrochemical-based treatment for NO_x reduction is employed by using electron shuttle or redox mediators. Here, four distinct redox mediators are used to address electrochemical obstacles, which effectively facilitate electron transportation and promoted NO_x reduction on the electrode surface. These mediators not only significantly enhanced the NO_x conversion into valuable products, i.e., N₂ and N₂O, but also made the process smooth with high performance. Among these mediators, neutral red (N.R) exhibited extraordinary potential in enhancing NO_x reduction. The obtained results indicated that the remarkable catalytic performance (∼93%) of the cMn@rGO can be attributed to several factors, including the catalyst's three-dimensional architecture structure and abundant active sites. The designed catalyst (cMn@rGO) is not only cost-effective and sustainable but also exhibits excellent potential in effectively reducing NO_x, which could be beneficial for large-scale NO_x abatement.