Weiyin Gao

One-pot synthesis of Ag/r-GO/TiO2 nanocomposites with high solar absorption and enhanced anti-recombination in photocatalytic applications

In this paper, we reported a simple one-pot solvothermal approach to fabricate Ag/reduced graphene oxide (r-GO)/TiO2 composite photocatalyst under atmospheric pressure. Based on the experimental data, we concluded that the introduction of Ag into classical graphene-TiO2 system (i) efficiently enlarges the absorption range, (ii) improves photogenerated electron separation and (iii) increases photocatalysis reaction sites. The optimized sample exhibits prominent photocatalysis ability as compared to pure TiO2 under simulated sunlight. We further proposed that besides the above three advantages of Ag, a different size of Ag nanoparticles is also responsible for the improved photocatalysis ability, where small size Ag nanoparticles (2-5 nm) could store a photoexcited electron that was generated from TiO2, while large-size Ag nanoparticles could utilize visible light due to their localized surface plasmon resonance (LSPR) absorption. Our present work gives new insights into the photocatalysis mechanism of noble metal/r-GO/TiO2 composites and provides a new pathway into the design of TiO2-based photocatalysts and promote their practical application in various environmental and energy issues.

One-dimensional (1D) [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) nanorods as an efficient additive for improving the efficiency and stability of perovskite solar cells

We report a novel one dimensional (1D) [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) nanorod material as an efficient additive to form a wrinkle-like bicontinuous perovskite layer, where 1D PCBM nanorods can distribute homogenously throughout the film with an enlarged grain size. The resultant interconnected 1D PCBM nanorod within the perovskite material can also efficiently facilitate the photo-generated charge separation and carrier transportation process. An improved solar cell performance, from 9.5% up to 15.3%, was achieved using the optimized 1D PCBM nanorod content, along with enhanced device working stability. This work gives a new insight towards designing high performance organic–inorganic perovskite solar cells.

Employing the plasmonic effect of the Ag–graphene composite for enhancing light harvesting and photoluminescence quenching efficiency of poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene-vinylene]

In this work, we report that the Ag-graphene composite (AGC) can effectively enhance the light harvesting and photoluminescence (PL) quenching efficiency of poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene-vinylene] (MEH-PPV). Loading the AGC on MEH-PPV leads to improved light absorption ability and PL quenching efficiency, which is due to the strong interaction between localized surface plasmon resonance (LSPR)-activated Ag nanoparticles and the MEH-PPV molecule. Control experiment reveals that the combination of graphene and Ag nanoparticles achieves superior light absorptivity and PL quenching ability compared with individual graphene and Ag NPs. The exponential shape of the Stern-Volmer plot implies that both Ag and graphene in the AGC can offer the quenching pathway for the PL quenching process. We also found that the AGC with a broader LSPR absorption range is competitive in enhancing the light absorption ability and PL quenching efficiency of the MEH-PPV-AGC composite, because it can expand LSPR-induced light harvesting and PL quenching response to a wider absorption range.

A general route to enhance the fluorescence of graphene quantum dots by Ag nanoparticles

Graphene quantum dots (GQDs)/Ag nanoparticles with an unexpected quantum yield of 16.3% are synthesized by an efficient simple solvothermal method at atmospheric pressure. Experimental results show that the enhanced fluorescence is caused by the plasmonic effect of the Ag nanoparticles. The possible mechanism of this fluorescence enhancement is also proposed.

High-Quality Cs2AgBiBr6 Double Perovskite Film for Lead-Free Inverted Planar Heterojunction Solar Cells with 2.2 % Efficiency

All-inorganic double-metal perovskite materials have recently gained much attention due to their three dimensionality (3D) and non-toxic nature to replace lead-based perovskite materials. Among all those double perovskite materials, theoretical works have demonstrated that Cs2 AgBiBr6 shows high stability and possesses a suitable band gap for solar-cell applications. However, the film-forming ability of Cs2 AgBiBr6 is found to be the utmost challenge hindering its development in thin-film solar-cell devices. In this work, a high-quality Cs2 AgBiBr6 film with ultra-smooth morphology, micro-sized grains, and high crystallinity is realized via anti-solvent dropping technology and post-annealing at high temperature. After optimization, the first example of an inverted planar heterojunction solar-cell device based on Cs2 AgBiBr6 exhibits a power conversion efficiency of 2.23 % with VOC =1.01 V, JSC =3.19 mA/cm2 , and FF=69.2 %. Besides, the device shows no hysteresis and a high stability.

One-pot synthesis of stabilizer-free Ag-Graphene Nanocomposite and its potential application on photodegradation of RhB

Simultaneous reduction of graphene oxide (GO) and silver nitrate (AgNO3) into stabilizer-free Ag-Graphene Naoncomposite (AGN) using DMAc-assisted thermal reduction method with controllable density of Ag nanoparticles (Ag NPs) is reported. Microscopy techniques (scanning electron microscopy and high-resolution transmission electron microscopy) have been employed to probe the morphological characteristics of AGN and the lattice plane of Ag NPs. We observed a significant improvement on adsorption ability of AGN-P25 mixture compared with bare P25, indicating potential application on photocatalysis of AGN.

Formation of charge-transfer complex and enlarging the absorption ability of MEH-PPV by Ag-Graphene Nanocomposite

In this work, we have synthesized Ag-Graphene Nanocompostie (AGN) by a simple method under mild condition. Further, Composites of poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) participated by AGN have been studied. The interaction and photoluminescence quenching of MEH-PPV/AGN composites have been observed using UV-visible and fluorescence spectroscopy. Based on UV-visible spectrum of different concentration of AGN blending with MEH-PPV, the absorption range was markedly enlarged, indicating the formation of ground-state charge-transfer complex (CTC). Besides, photoluminescence (PL) spectra of the MEH-PPV/AGN nanocomposite show an efficient PL quenching effect. Both of these results indicate that AGN could apply in photovoltaic device as an acceptor material.