Solar-driven photocatalytic removal of NO over a concrete paving eco-block containing black TiO2

Abstract

A dispersion containing black TiO₂ photocatalyst was prepared and sprayed onto the concrete's surface to achieve a black TiO₂-based photocatalytic concrete paving eco-block, and its photocatalytic NO removal ratio is approximately 1.7 times as high as that of a white TiO₂-based eco-block, resulting from the enhanced optical absorption intensity, abundant oxygen vacancies, and highly produced superoxide anion radicals (˙O₂⁻) of black TiO₂. Moreover, the black TiO₂-based concrete paving eco-block exhibits significantly enhanced compressive strength and abrasion resistance when using water-glass as a binder, which could satisfy the demand for practical application. Furthermore, in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) was performed to dynamically track the reactive products and intermediates across the surface of the B-TiO₂ photocatalyst in a time sequence to investigate the reaction mechanism. It has been demonstrated that almost no harmful by-products were produced when NO was removed via photocatalysis, and the applicability of the as-prepared eco-blocks was evaluated considering the effects of various reaction conditions. Additionally, a computational fluid dynamics (CFD) model for solar-driven photocatalytic abatement of atmospheric NO in a realistic urban street coating with black TiO₂-based photocatalytic concrete paving eco-blocks was constructed and simulated to assess the real-world applicability of the developed approach. Overall, this research may offer fresh perspectives on how to create ecologically acceptable photocatalytic products for the removal of air pollutants using solar light.