Strategy for Modifying Layered Perovskites toward Efficient Solar Light-Driven Photocatalysts for Removal of Chlorinated Pollutants

Abstract

We have explored an efficient strategy to enhance the overall photocatalytic performances of layered perovskites by increasing the density of hydroxyl group by protonation. The experimental procedure consisted of the slow replacement of interlayer Rb+ cation of RbLaTa2O7 Dion-Jacobson (DJ) perovskite by H+ via acid treatment. Two layered perovskites synthesized by mild (1200 °C for 18 h) and harsh (950 and 1200 °C, for 36 h) annealing treatment routes were used as starting materials. The successful intercalation of proton into D-J interlayer galleries was confirmed by FTIR spectroscopy, thermal analyses, ion chromatography and XPS results. In addition, the ion-exchange route was effective to enlarge the specific surface area, thus enhancing the supply of photocharges able to participate in redox processes involved in the degradation of organic pollutants. HLaTa_01 protonated layered perovskite is reported as a efficient photocatalyst for photomineralization of trichloroethylene (TCE) to Cl− and CO2 under simulated solar light. The enhanced activity is attributed to combined beneficial roles played by the increased specific surface area and high density of hydroxyl groups, leading to an efficiency of TCE mineralization of 68% moles after 5 h of irradiation.

Cost-effective preparation of layered tantalum oxynitrides for visible light-driven photocatalysis

“…† The oxide precursors KLaTa 2 O 7 and KCa 2 Ta 3 O 10 are white powders with an absorption edge at around 300 nm, suggesting that they have almost no absorption ability for visible light. According to the formula (ahv) 2 = α(hv − E g ), the band gap was calculated to be 3.83 and 3.91 eV for KLaTa 2 O 7 and KCa 2 Ta 3 O 10 , respectively, using the Tauc plots (Fig. S6 †), which is consistent with our previous report.…”

“…1 Among the many types of photocatalysts, layered perovskites provide the following benefits: (i) possibility of interlayer space maintainability and (ii) nanosized reaction interlayer spaces. 2,3 However, most layered perovskites have a wide band gap, causing them to only be photoactive under UV light and have low utilization efficiency for solar energy. 4 Thus, to further address this limitation, a number of strategies including transition metal and/or anion doping have been developed to tune their band gap and achieve a visible light response.…”

Dark–Light Tandem Catalytic Oxidation of Formaldehyde over SrBi2Ta2O9 Nanosheets

“…Thermal catalytic oxidation is significantly limited with higher reaction temperatures, which is high energy-consuming and not suitable for application in a natural environment. In strong contrast, solar radiation is an inexhaustible source of clean energy, which has been widely used in H 2 production [12,13], degradation of organic pollutants in water [14][15][16], degradation of VOCs in the air [3,17], etc. By photocatalytic oxidation, HCHO can be simultaneously oxidized to CO 2 and H 2 O by light irradiation at room temperature.…”

“…Layered perovskite materials, an emerging class of photocatalysts with unique crystal structures, have attracted increasing attention due to their high chemical stability, high absorption coefficients, and long carrier-diffusion lengths [12][13][14][15][16]. At present, layered perovskite materials have been found to have excellent photocatalytic performances in H 2 production from water splitting [13], CO 2 reduction [23], conversion of NO x in air [24,25], etc., but their applications in HCHO removal are rarely studied.…”

1H NMR Study of the HCa2Nb3O10 Photocatalyst with Different Hydration Levels

“…The ability to intercalate water molecules often plays a crucial role in other intercalation reactions and photocatalysis [ 9 , 29 , 30 , 31 ]. Hydrated protonated forms may comprise protons [ 13 , 30 ] or charged complexes like H + … n ·H 2 O in their interlayer slab [ 32 , 33 , 34 ]. Obviously, water content and its state and localization should affect both the pathway and efficiency of chemical or photocatalytic reactions.…”