Xufang Qian

Visible Light Assisted Heterogeneous Fenton-Like Degradation of Organic Pollutant via α-FeOOH/Mesoporous Carbon Composites

A novel α-FeOOH/mesoporous carbon (α-FeOOH/MesoC) composite prepared by in situ crystallization of adsorbed ferric ions within carboxyl functionalized mesoporous carbon was developed as a novel visible light assisted heterogeneous Fenton-like catalyst. The visible light active α-FeOOH nanocrystals were encapsulated in the mesoporous frameworks accompanying with surface attached large α-FeOOH microcrystals via C-O-Fe bonding. Assisting with visible light irradiation on α-FeOOH/MesoC, the mineralization efficiency increased owing to the photocatalytic promoted catalyzing H2O2 beyond the photothermal effect. The synergistic effect between α-FeOOH and MesoC in α-FeOOH/MesoC composite improved the mineralization efficiency than the mixture catalyst of α-FeOOH and MesoC. The iron leaching is greatly suppressed on the α-FeOOH/MesoC composite. Interestingly, the reused α-FeOOH/MesoC composites showed much higher phenol oxidation and mineralization efficiencies than the fresh catalyst and homogeneous Fenton system (FeSO4/H2O2). The XPS, XRD, FTIR, and textural property results reveal that the great enhancement comes from the interfacial emerged oxygen containing groups between α-FeOOH and MesoC after the first heterogeneous Fenton-like reaction. In summary, visible light induced photocatalysis assisted heterogeneous Fenton-like process in the α-FeOOH/MesoC composite system improved the HO• production efficiency and Fe(III)/Fe(II) cycle and further activated the interfacial catalytic sites, which finally realize an extraordinary higher degradation and mineralization efficiency.

Ion-Exchange-Induced 2D-3D Conversion of HMA1−x FAx PbI3 Cl Perovskite into a High-Quality MA1−x FAx PbI3 Perovskite

High-quality phase-pure MA1-x FAx PbI3 planar films (MA=methylammonium, FA=formamidinium) with extended absorption and enhanced thermal stability are difficult to deposit by regular simple solution chemistry approaches owing to crystallization competition between the easy-to-crystallize but unwanted δ-FAPbI3 /MAPbI3 and FAx MA1-x PbI3 requiring rigid crystallization conditions. Here A 2D-3D conversion to transform compact 2D mixed composition HMA1-x FAx PbI3 Cl perovskite precursor films into 3D MA1-x FAx PbI3 (x=0.1-0.9) perovskites is presented. The designed Cl/I and H/FA(MA) ion exchange reaction induced fast transformation of compact 2D perovskite film, helping to form the phase-pure and high quality MA1-x FAx PbI3 without δ-FAPbI3 and MAPbI3 impurity. In all, we successfully developed a facile one-step method to fabricate high quality phase-pure MA1-x FAx PbI3 (x=0.1-0.9) perovskite films by 2D-3D conversion of HMA1-x FAx PbI3 Cl perovskite. This 2D-3D conversion is a promising strategy for lead halide perovskite fabrication.

A general non-CH3NH3X (X = I, Br) one-step deposition of CH3NH3PbX3 perovskite for high performance solar cells

We demonstrate a facile non-CH3NH3I one-step fabrication of high quality CH3NH3PbI3 perovskite via direct gas/solid deposition of spin coating HI + PbI2 precursor solution in low concentration CH3NH2 atmospheres. This HI + PbI2 precursor solution was prepared by direct addition of stoichiometric aqueous HI acid into PbI2 DMF solution without any other chemicals. This novel one-step approach can be extended to fabricate different lead halide perovskites such as CH3NH3PbI2Br and C2H5NH2PbI3 by spin coating HBr + PbI2 precursor solution in CH3NH2 atmosphere or HI + PbI2 in C2H5NH2 atmosphere, respectively. In all, our novel one-step approach is a promising candidate for fabricating high performance perovskites by one-step reaction of gaseous CH3NH2 with HX and PbX2 (X = I, Br).

A simple fabrication of CH3NH3PbI3 perovskite for solar cells using low-purity PbI2 *

The CH3NH3PbI3 (MAPbI3) perovskite was usually prepared by high-purity PbI2 with high cost. The low cost and low-purity PbI2 was seldom reported for fabrication of MAPbI3 because it cannot even dissolve well in widely adopted solvent of DMF. We developed an easy method to adapt low-purity PbI2 for fabrication of high quality MAPbI3 just by the simple addition of some hydrochloric acid into the mixture of low-purity PbI2, MAI and DMF. This straightforward method can not only help dissolve the low quality PbI2 by reacting with some impurities in DMF, but also lead to a successful fabrication of high-quality perovskite solar cells with up to 14.80% efficiency comparable to the high quality PbI2 precursors.