A Novel Conversion of Ti-Bearing Blast-Furnace Slag into Water Splitting Photocatalyst with Visible-Light-Response
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n the view of global environmental and energy issues, hydrogen (H2) production from photocatalytic water splitting is considered as a promising solar energy conversion method.[1,2] Over the past 40 years, many photocatalysts reported, such as La-doped NaTaO3,[3] La2Ti2O7,[4] Sr2M2O7 (M = Nb, Ta),[5] K2La2Ti3O10,[6] and b-Ge3N4,[7] have been reported and exhibited high photocatalytic activities for splitting the water in the ultraviolet (UV) light region. However, it is rather difficult to directly apply these photocatalysts with wide band gap (band gap energy, Eg>3.2 eV) for water splitting because it can only become effective for the H2 production under the UV light irradiation (wavelength < 420 nm). In fact, the UV light accounts for only ca. 4 pct of the incoming solar energy, whereas the visible (vis) light occupies the most part of solar spectrum (46 pct). Therefore, in order to achieve efficient water splitting under abundant visible light irradiation, two main approaches have been adopted thus far:[1] (1) narrowing band gap by doping metal and/or nonmetal ions;[8] (2) dye sensitization to induce visible-lightresponse.[9]
HUIHONG LU¨, Associate Professor, NING LI, Graduate Student, XINGRONG WU and LIAOSHA LI, Professors, ZHIFANG GAO and XINGMEI SHEN, Lecturers, are with the Key Laboratory of Metallurgical Emission Reduction & Resources Recycling, Ministry of Education, Anhui University of Technology, Ma’anshan 243002, Anhui, P.R. China. Contact e-mail: [email protected] Manuscript submitted March 19, 2013. Article published online October 22, 2013. METALLURGICAL AND MATERIALS TRANSACTIONS B
As an important valuable resource, the titanium blastfurnace slag (Ti-slag) contains about 25 pct perovskite CaTiO3 (Eg = 3.5 eV), which has a high photocatalytic activity of decomposing water into H2 and O2 under the UV light.[10,11] Although many works have been done for the applications of Ti-slag (TS),[12–15] these reported methods are aimed at recovering only one of the component. Furthermore, silicates usually show the complicated phase behavior in the solution chemical process. Therefore, it is necessary to design a method to make use of the multicomponents of TS as much as possible in a simple step. In an earlier work, we had successfully prepared the multi-doped LiFePO4 from the steel slag and converter sludge.[16,17] And in order to explore the preparation of excellent silica sol from complicated silicic acid system, the condensation behavior of silicic acid in blast-furnace slag was also studied.[18] In the present work, a novel and simple approach for fabrication of the water splitting photocatalyst from the TS is reported. The TS used was from Pangang Group Company Ltd, China. Sodium nitrate and hydrochloric acid acting as analytical reagents were provided by Sinopharm Chemical Reagent Co., Ltd, China. Commercial perovskite CaTiO3 (CPC, purity > 99 pct) and dihydrogen hexachloroplatinate (purity ‡ 99.95 pct) deployed were brought from Alfa Aesar, USA. Analytical reagent methanol was supplied by Xilong Chemical Co.
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