Haihua Hu

Silver nanoparticles modified reduced graphene oxide wrapped Ag3PO4/TiO2 visible-light-active photocatalysts with superior performance

Silver nanoparticles (Ag NPs) modified reduced graphene oxide wrapped Ag3PO4/TiO2 (Ag3PO4/TiO2/Ag-rGO, Ag-ATG) photocatalysts have been developed through a rational design that combines the optimization of charge generation, separation and transfer in the composites, which helps to increase the photocatalytic performance. The Ag-ATG composites possess novel microstructure, in which TiO2 mesoporous spheres of hundreds of nanometers in size are decorated with dense nano-sized Ag3PO4 to form pinecone-liked Ag3PO4/TiO2 particles, which were further wrapped by rGO sheets that are selectively decorated with Ag NPs. The Ag-ATG composites exhibit improved photocatalytic performance toward degradation of methylene blue (MB) and methyl orange (MO) under visible light compared to bare Ag3PO4 and Ag3PO4/TiO2/rGO (ATG). The underlying mechanism has been studied based on the results of reactive oxygen species capture experiment, photoluminescence (PL) spectra, and photocurrent measurements under visible light and monochromatic lights. The improved photocatalytic performance is mainly ascribed to the efficient spatial separation of photo-induced electrons and holes in Ag-ATG, i.e., the electrons in Ag3PO4 transfer to Ag-rGO, meanwhile the holes in Ag3PO4 transfer to TiO2. Ag NPs play an important role in the hybrid structure owing to the synergistic effect of Ag NPs and rGO, which not only enhance the light harvest but also increase the capacity of electron accepting from Ag3PO4. Meanwhile, active photo-induced electrons at the plasmonic Ag NPs can facilitate the formation of O2˙− radicals for photocatalysis. As a result, both the stability and photocatalytic active of Ag-ATG are significantly improved.

CH3NH3PbBr3 Quantum Dot-Induced Nucleation for High Performance Perovskite Light-Emitting Solar Cells

Solution-processed organometallic halide perovskites have obtained rapid development for light-emitting diodes (LEDs) and solar cells (SCs). These devices are fabricated with similar materials and architectures, leading to the emergence of perovskite-based light-emitting solar cells (LESCs). The high quality perovskite layer with reduced nonradiative recombination is crucial for achieving a high performance device, even though the carrier behaviors are fundamentally different in both functions. Here CH3NH3PbBr3 quantum dots (QDs) are first introduced into the antisolvent in solution phase, serving as nucleation centers and inducing the growth of CH3NH3PbI3 films. The heterogeneous nucleation based on high lattice matching and a low free-energy barrier significantly improves the crystallinity of CH3NH3PbI3 films with decreased grain sizes, resulting in longer carrier lifetime and lower trap-state density in the films. Therefore, the LESCs based on the CH3NH3PbI3 films with reduced recombination exhibit improved electroluminescence and external quantum efficiency. The current efficiency is enhanced by 1 order of magnitude as LEDs, and meanwhile the power conversion efficiency increases from 14.49% to 17.10% as SCs, compared to the reference device without QDs. Our study provides a feasible method to grow high quality perovskite films for high performance optoelectronic devices.