Xiong Gao

Bio: Xiong Gao is an academic researcher from Tianjin University. The author has contributed to research in topics: Organic semiconductor & Thin film. The author has an hindex of 5, co-authored 8 publications receiving 261 citations.

Effective and Selective Catalysts for Cinnamaldehyde Hydrogenation: Hydrophobic Hybrids of Metal-Organic Frameworks, Metal Nanoparticles, and Micro- and Mesoporous Polymers.

Abstract: As for heterogeneous catalysis, the activity and selectivity are two key factors for evaluating catalysts. Metal-organic frameworks (MOFs) as selectivity regulators for catalytic reaction have attracted much attention, especially MOFs and metal nanoparticles (NPs) shelled structures, e.g., MOFs@NPs@MOFs. Nevertheless, the hydrophilic MOFs shell is challenging to gather hydrophobic reactants. Here, we innovate a new and viable approach to solve this problem. By employing conjugated micro- and mesoporous polymers with iron(Ⅲ) porphyrin (FeP-CMPs) as the new shell, MIL-101@Pt@FeP-CMP was fabricated firstly, which not only is hydrophobic and porous to enrich reactants, but also possesses iron sites to activate C=O bond and thereby regulate the selectivity for cinnamyl alcohol in hydrogenation of cinnamaldehyde. Interestingly, MIL-101(Cr)@Pt@FeP-CMPsponge can reach ultrahigh turnover frequency (TOF) as high as 1516.1 h-1 with 97.3 % selectivity towards cinnamyl alcohol and 97.6 % conversion. The results open up a new avenue for decorating and protecting MOFs and will play an important role in both academia and industry.

Solution‐Processed Centimeter‐Scale Highly Aligned Organic Crystalline Arrays for High‐Performance Organic Field‐Effect Transistors

Abstract: Solution-printed organic single-crystalline films hold great potential for achieving low-cost manufacturing of large-area and flexible electronics. For practical applications, organic field-effect transistor arrays must exhibit high performance and small device-to-device variation. However, scalable fabrication of highly aligned organic crystalline arrays is rather difficult due to the lack of control over the crystallographic orientation, crystal uniformity, and thickness. Here, a facile solution-printing method to fabricate centimeter-sized highly aligned organic crystalline arrays with a thickness of a few molecular layers is reported. In this study, the solution shearing technique is used to produce large-area, organic highly crystalline thin films. Water-soluble ink is printed on the hydrophobic surface of organic crystalline films, to selectively protect it, followed by etching. It is shown that the addition of a surfactant dramatically changes the fluid drying dynamics and increases the contact line friction of the aqueous solution to the underlying nonwetting organic crystalline film. As a result, centimeter-scale highly aligned organic crystalline arrays are successfully prepared on different substrates. The devices based on organic crystalline arrays show good performance and uniformity. This study demonstrates that solution printing is close to industrial application and also expands its applicability to various printed flexible electronics.

Scalable Fabrication of Highly Crystalline Organic Semiconductor Thin Film by Channel-Restricted Screen Printing toward the Low-Cost Fabrication of High-Performance Transistor Arrays.

Abstract: Control over the morphology and crystallinity of small-molecule organic semiconductor (OSC) films is of key importance to enable high-performance organic optoelectronic devices. However, such control remains particularly challenging for solution-processed OSC devices because of the complex crystallization kinetics of small-molecule OSC materials in the dynamic flow of inks. Here, a simple yet effective channel-restricted screen-printing method is reported, which uses small-molecule OSCs/insulating polymer to yield large-grained small-molecule OSC thin-film arrays with good crystallization and preferred orientation. The use of cross-linked organic polymer banks produces a confinement effect to trigger the outward convective flow at two sides of the channel by the fast solvent evaporation, which imparts the transport of small-molecule OSC solutes and promotes the growth of small-molecule OSC crystals parallel to the channel. The small-molecule OSC thin-film array produced by screen printing exhibits excellent performance characteristics with an average mobility of 7.94 cm2 V-1 s-1 and a maximum mobility of 12.10 cm2 V-1 s-1 , which are on par with its single crystal. Finally, screen printing can be carried out using a flexible substrate, with good performance. These demonstrations bring this robust screen-printing method closer to industrial application and expand its applicability to various flexible electronics.

High-performance optical memory transistors based on a novel organic semiconductor with nanosprouts

Abstract: Here, we developed a novel organic semiconductor of 2,7-di(anthracen-2-yl)naphthalene (2,7-DAN), which not only exhibits outstanding hole-transport with a mobility of 3.3 cm2 V-1 s-1 but also shows a high photoresponsivity of 8000 A W-1 with detectivity as high as 1.2 × 1014 Jones. Most importantly, optical memory transistors (OMTs) based on it display an excellent memory effect due to the inhomogeneity (nanosprouts) of the 2,7-DAN film only, different from traditional strategies towards memory devices like the application of a floating gate layer, an electret layer or a photochromic molecule. The findings distinctly make 2,7-DAN an excellent candidate for high performance nonvolatile OMTs with a simpler structure.

State of the Art and Prospects in Metal-Organic Framework (MOF)-Based and MOF-Derived Nanocatalysis.

Abstract: Metal-organic framework (MOF) nanoparticles, also called porous coordination polymers, are a major part of nanomaterials science, and their role in catalysis is becoming central. The extraordinary variability and richness of their structures afford engineering synergies between the metal nodes, functional linkers, encapsulated substrates, or nanoparticles for multiple and selective heterogeneous interactions and activations in these MOF-based nanocatalysts. Pyrolysis of MOF-nanoparticle composites forms highly porous N- or P-doped graphitized MOF-derived nanomaterials that are increasingly used as efficient catalysts especially in electro- and photocatalysis. This review first briefly summarizes this background of MOF nanoparticle catalysis and then comprehensively reviews the fast-growing literature reported during the last years. The major parts are catalysis of organic and molecular reactions, electrocatalysis, photocatalysis, and views of prospects. Major challenges of our society are addressed using these well-defined heterogeneous catalysts in the fields of synthesis, energy, and environment. In spite of the many achievements, enormous progress is still necessary to improve our understanding of the processes involved beyond the proof-of-concept, particularly for selective methane oxidation, hydrogen production, water splitting, CO2 reduction to methanol, nitrogen fixation, and water depollution.

Metal–Organic Frameworks in Heterogeneous Catalysis: Recent Progress, New Trends, and Future Perspectives

Abstract: More than 95% (in volume) of all of today’s chemical products are manufactured through catalytic processes, making research into more efficient catalytic materials a thrilling and very dynamic rese...

The role of the third component in ternary organic solar cells

Abstract: Ternary organic solar cells (TSCs) contain a single three-component photoactive layer with a wide absorption window, which is obtained without the need for multiple stacks. Subsequently, TSCs have attracted great interest in the photovoltaics field. Through careful selection of the three (or more) active components that form the photoactive layer, all photovoltaic parameters can be simultaneously enhanced within a TSC — a strategy that has resulted in record efficiencies for single-junction solar cells. In this Review, we outline key developments in TSCs, with a focus on the central role of the third component in achieving record efficiencies. We analyse the effects of the third component on the nanomorphology of the bulk heterojunction and the photovoltaic parameters of TSCs. Moreover, we discuss the charge-transfer and/or energy-transfer mechanisms and nanomorphology models that govern the operation of TSCs. We consider both polymer and small-molecule donors as well as fullerenes and recently developed non-fullerene acceptors. In addition, we summarize the recent success of TSCs in mitigating the stability issues of binary solar cells. Finally, we provide a perspective on the advantages of ternary blends and suggest design strategies for highly efficient and stable devices for commercial photovoltaics. Adding a third component into a binary blend is a promising strategy for simultaneously improving all photovoltaic parameters in organic solar cells. In this Review, we discuss the role of the third component in influencing the energetics, charge-carrier recombination and stability in ternary solar cells.

Metal-Organic Frameworks Encapsulating Active Nanoparticles as Emerging Composites for Catalysis: Recent Progress and Perspectives.

Abstract: Beyond conventional porous materials, metal-organic frameworks (MOFs) have aroused great interest in the construction of nanocatalysts with the characteristics of catalytically active nanoparticles (NPs) confined into the cavities/channels of MOFs or surrounded by MOFs. The advantages of adopting MOFs as the encapsulating matrix are multifold: uniform and long-range ordered cavities can effectively promote the mass transfer and diffusion of substrates and products, while the diverse metal nodes and tunable organic linkers may enable outstanding synergy functions with the encapsulated active NPs. Herein, some key issues related to MOFs for catalysis are discussed. Then, state-of-the art progress in the encapsulation of catalytically active NPs by MOFs as well as their synergy functions for enhanced catalytic performance in the fields of thermo-, photo-, and electrocatalysis are summarized. Notably, encapsulation-structured nanocatalysts exhibit distinct advantages over conventional supported catalysts, especially in terms of the catalytic selectivity and stability. Finally, challenges and future developments in MOF-based encapsulation-structured nanocatalysts are proposed. The aim is to deliver better insight into the design of well-defined nanocatalysts with atomically accurate structures and high performance in challenging reactions.

Metal-Organic Framework Composites for Catalysis

Abstract: Metal-organic frameworks (MOFs) have emerged as a promising class of materials with several unique properties, such as high porosity, diverse composition, tunable pore structures, and versatile functionality. These characteristics enable MOFs to show potential in the field of heterogeneous catalysis. To satisfy the practical applications of MOFs, controllable integration of MOFs and functional materials (e.g., metal nanoparticles, quantum dots, polyoxometalates, molecular species, enzymes, silica, and polymers) can enhance the characteristics of MOFs through activity improvement and framework stabilization. In MOF composites/hybrids, functional materials can cooperatively work with MOFs to show enhanced catalytic activity, selectivity, and stability in a variety of chemical transformations. This review provides an overview of the significant advances in the development of diverse MOF composites/hybrids with special emphases on the preparation and catalytic applications.