Qiaoqi Guo,Jun Xu,Ying Luo,Yang Yang,Zheng Wang,Hong He
The concept of photocatalytic CO2 conversion provides simultaneous solutions for global warming mitigation and fuel generation, while the lack of efficient photocatalysts restrains the development of photocatalytic CO2 conversion. AgTaO3 with the appropriate band position for CO2 reduction has been used as an active photocatalyst for one-step excitation overall water splitting. Therefore, if there are suitable reduction active sites on the surface, AgTaO3 can be expected to conduct photocatalytic reduction of CO2. Herein, we first discovered the photocatalytic activity of AgTaO3 for CO2 conversion with H2O. Through the optimization of synthesis conditions and surface modification with various cocatalysts by different approaches, AgTaO3 with Ag cocatalyst loaded by photodeposition showed the highest activity for CO production among those with Pt, Rh, or Cu cocatalysts. When combining core/shell structured metal nanoparticles and Cr2O3, AgTaO3 photocatalyst exhibited CH4 evolution activity in photocatalytic conversion CO2, indicating Cr2O3 species promoted the hydrogenation process of CO2 reduction. This study demonstrated that cocatalyst decoration controlled the conversion products and played an important role in the multielectron photoreduction of CO2.
Starting from two wide band gap semiconductors AgTaO 3 and SrTiO 3 , we managed to reduce the band gap by forming their solid solutions, i.e. (AgTaO 3 ) 1-x (SrTiO 3 ) x (0.0 ≤ x ≤ 1.0). These solid solutions all adopt cubic perovskite structure similar to SrTiO 3 and high temperature phase of AgTaO 3 , suggesting that SrTiO 3 is helpful to stabilize AgTaO 3 in its high temperature cubic phase. Substantial improvements over photocatalytic hydrogen production were realized in these solid solutions which clearly outperform their parent compounds AgTaO 3 and SrTiO 3 . In-situ exolution of silver nanoparticles at the surface of solid solutions (x = 0.2) substantially strengthen the visible light absorption due to localized surface plasmons of these silver nanoparticles . This contributes to further improvements on both photocatalytic hydrogen and oxygen production under visible light illumination (λ ≥ 400 nm). Apparent quantum efficiency as high as ˜ 2.02% and ˜ 0.11% was achieved at solid solutions (x = 0.2) decorated with silver nanoparticles for full range (λ ≥ 250 nm) and visible light (λ ≥ 400 nm) illumination respectively. Photoelectrochemical analysis suggests that solid solutions own a better charge separation conditions than their parent compounds. Furthermore, the band edge positions of solid solutions (x = 0.2) lie approximately in the middle between AgTaO 3 and SrTiO 3 , being ideal for solar water splitting reactions.
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