A broad spectrum absorption photocatalytic system has been expected for a long time, especially for catalysts where the absorption mainly concentrates on the ultraviolet region, like TiO2. Here, dye sensitization was used to realize this expectation for TiO2. Anatase TiO2 was prepared by a hydrothermal method and then modified with Cu nanoparticles (NPs) by chemical reduction reaction. The highest H2 production rate was 3.33 mmol g−1 h−1 for Cu(3%)–TiO2 (content of Cu NPs was 3 wt%) and for pure TiO2 was only 0.356 mmol g−1 h−1. Next, the Cu(3%)–TiO2 photocatalyst was sensitized with various amounts of Erythrosin B (ErB) and the highest H2 production rate was 13.4 mmol g−1 h−1 with 3 mg of ErB in the photoreaction system. Under monochromatic light irradiation (500, 550, 600 and 650 nm), no photocatalytic activity was detected for Cu(3%)–TiO2 and some photocatalytic activities were obtained for sensitized Cu(3%)–TiO2, indicating that ErB sensitization can extend the visible light harvesting ability efficiently. Through photoelectrochemical analysis, electron–hole separation and transfer processes were promoted significantly by modification with Cu NPs and then sensitization by ErB. A possible ErB sensitization mechanism is proposed between ErB and Cu–TiO2 for the improvement of the photocatalytic activity.
Lejun Chen,Yonggang Lei,Yue Yang,Jianying Huang,Weiying Zhang,Kim Hoong Ng,Yuekun Lai
Metal-doping is a common strategy for establishing active sites on photocatalyst, but appropriately exposing them for maximized atomic utilization remains a great challenge in photocatalytic research. Herein, we propose a metal organic framework (MOF)-assisted approach to synthesis copper-modified titania (Cu-TiO 2 /Cu) photocatalyst with homogenously distributed and highly accessible active sites in its matrix. Significantly, an MOF precursor, namely NH 2 -MIL-125, with co-chelation of titania (Ti) and copper (Cu) was subjected to mild calcination, subsequently results in Cu-modified TiO 2 with highly accessible channels to its inner surface. These channels provide not only a large reactive surface (>400 m 2 g -1 ); they also enable facile modifying route for the pre-deposited Cu in prior to photoreaction. Specifically, NH 3 treatment was applied to partially reduce deposited Cu ions (Cu + and Cu 2+ ) into Cu nanoparticles, where their interplays realize improved optical properties and charge separation during photoreactions. Furthermore, the NH 3 -induced Cu nanoparticles could also serve as the adsorptive site for H + , thereby enabling 5629 μmol h -1 g -1 H 2 generation over the optimum photocatalyst of Cu 20 /TiO 2 /Cu 500 . Such performance is associated to 35.44 and 1.71-fold improvements compared to pure TiO 2 (Cu 0 /TiO 2 ) and untreated Cu-ion modified TiO 2 (Cu 20 /TiO 2 ), respectively. This work offers a new synthetic strategy for obtaining photocatalyst with evenly distributed and highly accessible active sites, thus improving the commensurability of photocatalytic H 2 generation from the industrial perspective.
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