As a fascinating conjugated polymer, graphitic carbon nitride (g-C3N4) has become a new research hotspot and drawn broad interdisciplinary attention as a metal-free and visible-light-responsive photocatalyst in the arena of solar energy conversion and environmental remediation. This is due to its appealing electronic band structure, high physicochemical stability, and “earth-abundant” nature. This critical review summarizes a panorama of the latest progress related to the design and construction of pristine g-C3N4 and g-C3N4-based nanocomposites, including (1) nanoarchitecture design of bare g-C3N4, such as hard and soft templating approaches, supramolecular preorganization assembly, exfoliation, and template-free synthesis routes, (2) functionalization of g-C3N4 at an atomic level (elemental doping) and molecular level (copolymerization), and (3) modification of g-C3N4 with well-matched energy levels of another semiconductor or a metal as a cocatalyst to form heterojunction nanostructures. The constructi...

Graphitic Carbon Nitride (g-C3N4)-Based Photocatalysts for Artificial Photosynthesis and Environmental Remediation: Are We a Step Closer To Achieving Sustainability?

A review on g-C3N4-based photocatalysts

We developed two-step solution-phase reactions to form hybrid materials of Mn3O4 nanoparticles on reduced graphene oxide (RGO) sheets for lithium ion battery applications. Mn3O4 nanoparticles grown selectively on RGO sheets over free particle growth in solution allowed for the electrically insulating Mn3O4 nanoparticles wired up to a current collector through the underlying conducting graphene network. The Mn3O4 nanoparticles formed on RGO show a high specific capacity up to ~900mAh/g near its theoretical capacity with good rate capability and cycling stability, owing to the intimate interactions between the graphene substrates and the Mn3O4 nanoparticles grown atop. The Mn3O4/RGO hybrid could be a promising candidate material for high-capacity, low-cost, and environmentally friendly anode for lithium ion batteries. Our growth-on-graphene approach should offer a new technique for design and synthesis of battery electrodes based on highly insulating materials.

Mn3O4-Graphene Hybrid as a High Capacity Anode Material for Lithium Ion Batteries

Ionic liquids (ILs) are liquids consisting entirely of ions and can be further defined as molten salts having melting points lower than 100 °C. One of the most important research areas for IL utilization is undoubtedly their energy application, especially for energy storage and conversion materials and devices, because there is a continuously increasing demand for clean and sustainable energy. In this article, various application of ILs are reviewed by focusing on their use as electrolyte materials for Li/Na ion batteries, Li-sulfur batteries, Li-oxygen batteries, and nonhumidified fuel cells and as carbon precursors for electrode catalysts of fuel cells and electrode materials for batteries and supercapacitors. Due to their characteristic properties such as nonvolatility, high thermal stability, and high ionic conductivity, ILs appear to meet the rigorous demands/criteria of these various applications. However, for further development, specific applications for which these characteristic properties becom...

Application of Ionic Liquids to Energy Storage and Conversion Materials and Devices

Replacing the rare and precious platinum (Pt) electrocatalysts with earth-abundant materials for promoting the oxygen reduction reaction (ORR) at the cathode of fuel cells is of great interest in developing high-performance sustainable energy devices. However, the challenging issues associated with non-Pt materials are still their low intrinsic catalytic activity, limited active sites, and the poor mass transport properties. Recent advances in material sciences and nanotechnology enable rational design of new earth-abundant materials with optimized composition and fine nanostructure, providing new opportunities for enhancing ORR performance at the molecular level. This Review highlights recent breakthroughs in engineering nanocatalysts based on the earth-abundant materials for boosting ORR.

Earth-Abundant Nanomaterials for Oxygen Reduction.

Despite the high theoretical capacity as the anode material of lithium-ion batteries (LIBs), Co3O4 is subjected to rapid capacity decline and poor rate performance owing to its severe volume expans...

Space-Confined Synthesis of Yolk–Shell Structured Co3O4/Nitrogen-Doped Carbon Nanocomposites with Hollow Mesoporous Carbon Nanocages as Advanced Functional Anodes for Lithium-Ion Batteries

ZIF-8, a zeolite-type metal-organic framework (MOF), is an effective carrier to support nanocatalysts for applications in the catalysis areas due to its high chemical and thermal stability, and unique structure. The ability to reconstruct the structure of ZIF-8 opens up the potential to enhance its performance in catalysis. In this work, the structure of hydrophobic ZIF-8 crystal is engineered to form hydrophilic hierarchically-porous nanoflowers (HHNs) by using an organic weak acid as etchant. Results reveal that besides imparting hydrophilicity to ZIF-8, the uniform micropores in ZIFs are transformed to mesopores and macropores, which are beneficial to nanoparticle immobilization and electrochemical reactions. After incorporating Cu nanoparticles into the matrix HHNs, the composite Cu@HHNs manifest superior catalytic activities for glucose electro-catalytic oxidation under alkaline media, compared with Cu nanoparticles loaded on untreated ZIF-8. The proposed Cu@HHNs based sensor displays exceptional sensing performances with a linear range of 5 μM to 3 mM, a detection limit of 1.97 μM (signal-to-noise ratio (S/N) of 3), a sensitivity of 1594.2 μA mM−1 cm−2, and high selectivity, specificity, and reproducibility. In addition, Cu@HHNs can be utilized for glucose sensing in human blood serum, demonstrating its feasibility toward determination of glucose for practical sample testing.

Reconstructing hydrophobic ZIF-8 crystal into hydrophilic hierarchically-porous nanoflowers as catalyst carrier for nonenzymatic glucose sensing

Fluorescence sensor for organophosphorus pesticide detection based on the alkaline phosphatase-triggered reaction.

A biomass derived nitrogen doped carbon fibers as efficient catalysts for the oxygen reduction reaction

In this study, manganese oxide nanowires wrapped by nitrogen-doped carbon layers (MnOx@NCs) were prepared by carbonization of poly(o-phenylenediamine) layer coated onto MnO2 nanowires for high performance supercapacitors. The component and structure of the MnOx@NCs were controlled through carbonization procedure under different temperatures. Results demonstrated that this composite combined the high conductivity and high specific surface area of nitrogen-doped carbon layers with the high pseudo-capacitance of manganese oxide nanowires. The as-prepared MnOx@NCs exhibited superior capacitive properties in 1 M Na2SO4 aqueous solution, such as high conductivity (4.167 × 10−3 S cm−1), high specific capacitance (269 F g−1 at 10 mV s−1) and long cycle life (134 F g−1 after 1200 cycles at a scan rate of 50 mV s−1). It is reckoned that the present novel hybrid nanowires can serve as a promising electrode material for supercapacitors and other electrochemical devices.

Anran Liu

Papers

Space-Confined Synthesis of Yolk–Shell Structured Co3O4/Nitrogen-Doped Carbon Nanocomposites with Hollow Mesoporous Carbon Nanocages as Advanced Functional Anodes for Lithium-Ion Batteries

Reconstructing hydrophobic ZIF-8 crystal into hydrophilic hierarchically-porous nanoflowers as catalyst carrier for nonenzymatic glucose sensing

Fluorescence sensor for organophosphorus pesticide detection based on the alkaline phosphatase-triggered reaction.

A biomass derived nitrogen doped carbon fibers as efficient catalysts for the oxygen reduction reaction

Manganese oxide nanowires wrapped with nitrogen doped carbon layers for high performance supercapacitors.