Intense Visible-Light Absorption in SrRuO3/C3N4 Heterostructures for the Highly Efficient Reduction of Hg(II)

Strontium ruthenium oxide (SrRuO3) is recognized as a metallic itinerant ferromagnet and utilized as a conducting electrode in heterostructure oxides with unforeseen optical characteristics, including remarkably low-reflection and high-absorption visible-light spectrum compared to classical metals. By coupling mesoporous SrRuO3 nanoparticles (NPs) with porous g-C3N4 nanosheets for the first time, we evidence remarkably promoted visible light absorption and superior photocatalytic performances for Hg­(II) reduction under illumination with visible light. The photocatalytic performance of g-C3N4 increased upon boosting the SrRuO3 percentage to 1.5%, and this (1.5% SrRuO3/g-C3N4 heterostructure) is considered the optimum condition to obtain a high photocatalytic efficiency of about 100% within 50 min. It was promoted 3.68 and 5.75 times compared to SrRuO3 and g-C3N4, respectively. Also, a Hg­(II) reduction rate of 1.5% SrRuO3/g-C3N4 was enhanced3.84- and 6.28-fold than those of pure SrRuO3 NPs and g-C3N4, respectively. Such a high photocatalytic performance over SrRuO3/g-C3N4 photocatalysts was explained by the characteristics of SrRuO3 NPs incorporated on porous g-C3N4 layers, which demonstrate strong absorption of visible light with a narrow band gap, a large photocurrent density of ∼9.07 mA/cm2, well-dispersed and small particle sizes, and cause facile diffusion of HCOOH and Hg­(II) ions and electrons. The present work provides a dramatic novel approach to the challenge of constructing visible-light photosensitive photocatalysts for wastewater remediation.