Iron Nanoparticles Confined in Periodic Mesoporous Organosilicon as Nanoreactors for Efficient Nitrate Reduction

Continuous accumulation of nitrate in water will lead to the imbalance of the nitrogen cycle in nature, which brings about great threat to the human health and social environment. Therefore, it is urgent to develop a simple and effective technology to repair nitrate-polluted water. Due to the rapid development of nanomaterials, electrocatalytic nitrate reduction technology has been widely used. Among them, iron-based materials with low price and high catalytic activity are in high demand. Herein, we report a highly active zero-valence iron@periodic mesoporous organosilicon (Fe@PMO) nanocomposite with spherical Fe nanoparticles as the basic structural unit and phenylene-bridged mesoporous organosilica as silicon and carbon sources. PMO shows the characteristic of a rigid organic–inorganic hybrid skeleton, which plays an important role in the spatial confinement of Fe nanoparticles and avoids the corrosion of the electrolyte to the active sites in the process of electrocatalysis. The obtained Fe@PMO catalyst exhibits an excellent nitrate conversion efficiency of 90% and a nitrogen selectivity of 99%. This study provides an innovative strategy to construct efficient electrocatalysts for nitrate reduction.