3D/2D photocatalyst fabricated from Pt loading TiO2 nanoparticles and converter slag-derived Fe-doped hydroxyapatite for efficient H2 evolution

Abstract

H2 generation for partially substituting coke by the photocatalysts fabricated from steel slag presents a desirable approach to on-site carbon footprint reduction in the iron and steel-making industry, both environmentally and economically. However, achieving high photocatalytic H2 production activity is primarily limited by the scarcity of active sites due to a small specific surface area, inefficient charge transfer, and partly restricted by slow kinetics of the H2 generation reaction. In this study, 1 wt% Pt clusters are photo-reduced onto sub-15 nm TiO2 nanoparticles (TiO2-Pt) in 20 vol% methanol. Subsequently, the electrostatic assembling method has been employed to combine steel-making converter slag-derived Fe-doped hydroxyapatite (FeHAp) with TiO2-Pt, forming a type II 3D/2D TiO2-Pt/FeHAp heterojunction. Excellent connectivity between these two phases contributes to efficient charge separation, forming a built-in electric field that drives the photo-generated electrons to flow from FeHAp to the Pt cocatalyst on TiO2 nanoparticles through the type-II path. By the synergistic effects, including the large specific surface of sub-15 nm TiO2, Pt cocatalyst-offered rapid H2 generation kinetics,. and the heterostructure-provided enhancement of interfacial charge migration and separation, 60 mg TiO2-Pt/5FeHAp presents an enhanced H2 production activity in 120 mL of 10 vol% triethanolamine (TEOA), enabling the H2 generation rate (3026 μmol·g−1·h−1) to reach 1.85 and 75.78 times greater than that of pristine TiO2-Pt (1638 μmol·g−1·h−1) and FeHAp-Pt (40 μmol·g−1·h−1), respectively, under UV–visible light irradiation for 3 h at 8 °C and obtaining an apparent quantum yield of 4.72 % at 370 nm. This study provides a promising strategy for green hydrogen-based steel-making in the sustainable development of the steel industry.