Muqing Chen

Bio: Muqing Chen is an academic researcher from University of Science and Technology of China. The author has contributed to research in topics: Fullerene & Endohedral fullerene. The author has an hindex of 14, co-authored 60 publications receiving 741 citations. Previous affiliations of Muqing Chen include University of Education, Winneba & Huazhong University of Science and Technology.

Stabilizing black phosphorus nanosheets via edge-selective bonding of sacrificial C 60 molecules.

Abstract: Few-layer black phosphorus (BP) with an anisotropic two-dimensional (2D)-layered structure shows potential applications in photoelectric conversion and photocatalysis, but is easily oxidized under ambient condition preferentially at its edge sites. Improving the ambient stability of BP nanosheets has been fulfilled by chemical functionalization, however this functionalization is typically non-selective. Here we show that edge-selective functionalization of BP nanosheets by covalently bonding stable C60 molecules leads to its significant stability improvement. Owing to the high stability of the hydrophobic C60 molecule, C60 functions as a sacrificial shield and effectively protects BP nanosheets from oxidation under ambient condition. C60 bonding leads to a rapid photoinduced electron transfer from BP to C60, affording enhanced photoelectrochemical and photocatalytic activities. The selective passivation of the reactive edge sites of BP nanosheets by sacrificial C60 molecules paves the way toward ambient processing and applications of BP.

Azide Passivation of Black Phosphorus Nanosheets: Covalent Functionalization Affords Ambient Stability Enhancement.

Abstract: Two-dimensional (2D) black phosphorus (BP) has a unique band structure, but it suffers from low ambient stability owing to its high reactivity to oxygen. Covalent functionalization has been demonstrated to passivate the reactive BP effectively, however the reported covalent functionalization methods are quite limited to aryl diazonium and nucleophilic additions affording P-C and P-O-C single bonds, for which the retaining of one unpaired electron in the Group 15 phosphorus atom hampers the passivation effect. Now, covalent azide functionalization of BP nanosheets (BPNSs) is reported, leading to significant enhancement of the ambient stability of BP as confirmed by UV/Vis spectroscopic studies. The most stable configuration of the azide functionalized BPNSs (f-BPNSs) is predicted by theoretical calculations, featuring the grafting of benzoic acid moiety onto BPNSs via the unprecedented P=N double bonds formed through in situ nitrene as a reactive intermediate.

Hybrids of Fullerenes and 2D Nanomaterials.

Abstract: Fullerene has a definite 0D closed-cage molecular structure composed of merely sp2-hybridized carbon atoms, enabling it to serve as an important building block that is useful for constructing supramolecular assemblies and micro/nanofunctional materials. Conversely, graphene has a 2D layered structure, possessing an exceptionally large specific surface area and high carrier mobility. Likewise, other emerging graphene-analogous 2D nanomaterials, such as graphitic carbon nitride (g-C3N4), transition-metal dichalcogenides (TMDs), hexagonal boron nitride (h-BN), and black phosphorus (BP), show unique electronic, physical, and chemical properties, which, however, exist only in the form of a monolayer and are typically anisotropic, limiting their applications. Upon hybridization with fullerenes, noncovalently or covalently, the physical/chemical properties of 2D nanomaterials can be tailored and, in most cases, improved, significantly extending their functionalities and applications. Here, an exhaustive review of all types of hybrids of fullerenes and 2D nanomaterials, such as graphene, g-C3N4, TMDs, h-BN, and BP, including their preparations, structures, properties, and applications, is presented. Finally, the prospects of fullerene-2D nanomaterial hybrids, especially the opportunity of creating unknown functional materials by means of hybridization, are envisioned.

Pyridine-functionalized fullerene additive enabling coordination interactions with CH3NH3PbI3 perovskite towards highly efficient bulk heterojunction solar cells

Abstract: Incorporating n-type fullerene derivatives into the perovskite layer affording bulk heterojunction (BHJ) perovskite solar cells (PSCs) is an effective strategy to passivate trap states, consequently reducing the current–voltage hysteresis and improving the device performance. Herein, we report the synthesis of a novel pyridine-functionalized fullerene derivative (C60-PyP) via a 1,3-dipolar cycloaddition reaction, and the unambiguous determination of its molecular structure by X-ray single crystal diffraction. Upon incorporating C60-PyP as an additive with an optimized doping ratio of 0.13 wt% into the CH3NH3Pbl3 (MAPbI3) perovskite precursor, the regular-structure bulk heterojunction PSC devices exhibit a best power conversion efficiency (PCE) of 19.82%, which is dramatically enhanced relative to that of the control devices (17.61%). The C60-PyP additive provides heterogeneous nucleation sites, leading to the decrease of the nucleation Gibbs free energy and consequently enlarged grain size and improved crystallization of the MAPbI3 perovskite film. Besides, incorporation of C60-PyP results in enhanced crystalline orientation as confirmed by grazing-incidence X-ray diffraction (GIXRD) measurements. Meanwhile, the coordination interaction between the N atom of the pyridine moiety within C60-PyP and the Pb2+ ion within MAPbl3 leads to the passivation of the trap states of the perovskite layer, jointly contributing to the improved device performance and markedly suppressed current–voltage hysteresis. Moreover, the ambient stability of the devices is improved upon C60-PyP incorporation due to the hydrophobic nature of the C60-PyP molecule, which presumably resides at the grain boundaries.

Functionalization of fullerene materials toward applications in perovskite solar cells

Abstract: Fullerene materials exhibit high electron affinity, high electron mobility and small reorganization energy, thus they have been widely utilized as electron transport layers, cathode interfacial layers and trap passivators in constructing efficient organic–inorganic hybrid halide perovskite solar cells (PSCs). Herein, we summarize the recent progress of functionalized fullerene materials (i.e., fullerene derivatives) which have been applied in PSCs, focusing on chemical functionalization strategies. We provide exhaustive lists of all reported fullerene derivatives applied in PSCs, and categorize them based on the types of addend groups and addition patterns. In particular, we manage to unveil the correlation between the chemical structures of fullerene derivatives, especially the addend groups, and their performance in improving the PSC device efficiency and stability. Finally, we propose an outlook on the future development of fullerene derivatives in realizing high-performance PSC devices.

NHCs in Main Group Chemistry.

Abstract: Since the discovery of the first stable N-heterocyclic carbene (NHC) in the beginning of the 1990s, these divalent carbon species have become a common and available class of compounds, which have found numerous applications in academic and industrial research. Their important role as two-electron donor ligands, especially in transition metal chemistry and catalysis, is difficult to overestimate. In the past decade, there has been tremendous research attention given to the chemistry of low-coordinate main group element compounds. Significant progress has been achieved in stabilization and isolation of such species as Lewis acid/base adducts with highly tunable NHC ligands. This has allowed investigation of numerous novel types of compounds with unique electronic structures and opened new opportunities in the rational design of novel organic catalysts and materials. This Review gives a general overview of this research, basic synthetic approaches, key features of NHC–main group element adducts, and might be...