/pdf/heterostructures-for-electrochemical-hydrogen-evolution-4gcg77rua6.pdf

Heterostructures for Electrochemical Hydrogen Evolution Reaction: A Review

Two-dimensional MXenes: From morphological to optical, electric, and magnetic properties and applications

Biosensors with high sensitivity, selectivity and a low limit of detection, reaching nano/picomolar concentrations of biomolecules, are important to the medical sciences and healthcare industry for evaluating physiological and metabolic parameters. Over the last decade, different nanomaterials have been exploited to design highly efficient biosensors for the detection of analyte biomolecules. The discovery of graphene has spectacularly accelerated research on fabricating low-cost electrode materials because of its unique physical properties, including high specific surface area, high carrier mobility, high electrical conductivity, flexibility, and optical transparency. Graphene and its oxygenated derivatives, including graphene oxide (GO) and reduced graphene oxide (rGO), are becoming an important class of nanomaterials in the field of biosensors. The presence of oxygenated functional groups makes GO nanosheets strongly hydrophilic, facilitating chemical functionalization. Graphene, GO and rGO nanosheets can be easily combined with various types of inorganic nanoparticles, including metals, metal oxides, semiconducting nanoparticles, quantum dots, organic polymers and biomolecules, to create a diverse range of graphene-based nanocomposites with enhanced sensitivity for biosensor applications. This review summarizes the advances in two-dimensional (2D) and three-dimensional (3D) graphene-based nanocomposites as emerging electrochemical and fluorescent biosensing platforms for the detection of a wide range of biomolecules with enhanced sensitivity, selectivity and a low limit of detection. The biofunctionalization and nanocomposite formation processes of graphene-based materials and their unique properties, surface functionalization, enzyme immobilization strategies, covalent immobilization, physical adsorption, biointeractions and direct electron transfer (DET) processes are discussed in connection with the design and fabrication of biosensors. The enzymatic and nonenzymatic reactions on graphene-based nanocomposite surfaces for glucose- and cholesterol-related electrochemical biosensors are analyzed. This review covers a very broad range of graphene-based electrochemical and fluorescent biosensors for the detection of glucose, cholesterol, hydrogen peroxide (H2O2), nucleic acids (DNA/RNA), genes, enzymes, cofactors nicotinamide adenine dinucleotide (NADH) and adenosine triphosphate (ATP), dopamine (DA), ascorbic acid (AA), uric acid (UA), cancer biomarkers, pathogenic microorganisms, food toxins, toxic heavy metal ions, mycotoxins, and pesticides. The sensitivity and selectivity of graphene-based electrochemical and fluorescent biosensors are also examined with respect to interfering analytes present in biological systems. Finally, the future outlook for the development of graphene based biosensing technology is outlined.

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A review on graphene-based nanocomposites for electrochemical and fluorescent biosensors

Exposing the highly active facets and hybridizing the photocatalyst with appropriate cocatalysts with right placement have been regarded as a powerful approach to high performance photocatalysts. Herein, TiO2 nanosheets (NSs) are in situ grown on highly conductive Ti3C2 MXene and then MoS2 NSs are deposited on the (101) facets of TiO2 NSs with mainly exposed high-active (001) facets through a two-step hydrothermal method. And a unique 2D-2D-2D structure of Ti3C2@TiO2@MoS2 composite is achieved. With an optimized MoS2 loading amounts (15 wt%), the Ti3C2@TiO2@MoS2 composite shows a remarkable enhancement in the photocatalytic H2 evolution reaction compared with Ti3C2@TiO2 composite and TiO2 NS. It also shows good stability under the reaction condition. This arises from: (i) the in situ growth of TiO2 NSs construct strong interfacial contact with excellent electronic conductivity of Ti3C2, which facilitates the separation of carriers; (ii) the coexposed (101) and (001) facets can form a surface heterojunction within single TiO2 NS, which is beneficial for the transfer and separation of charge carriers; and (iii) the MoS2 NSs are deposited on the electrons-rich (101) facets of TiO2 NSs, which not only effectively reduces the charge carriers recombination rate by capturing photoelectrons, but also makes TiO2 NSs expose more highly active (001) facets to afford high-efficiency photogeneration of electron-hole pairs.

2D/2D/2D heterojunction of Ti3C2 MXene/MoS2 nanosheets/TiO2 nanosheets with exposed (001) facets toward enhanced photocatalytic hydrogen production activity

Seeking for a suitable cocatalyst to realize highly efficient photocatalytic hydrogen (H2) production is a great challenge in the field of solar energy conversion. Herein, hollow cobalt sulfide (Co...

Hollow CoSx Polyhedrons Act as High-Efficiency Cocatalyst for Enhancing the Photocatalytic Hydrogen Generation of g-C3N4

Developing highly efficient noble-metal-free electrocatalysts for hydrogen evolution reaction (HER) has attracted increasing attentions. Here, we report a simple strategy to synthesize the hierarchical “nanoroll” like MoS2/Ti3C2Tx hybrid by combining liquid nitrogen-freezing and subsequent annealing. The quick freezing of the Ti3C2Tx nanosheets and ammonium tetrathiomolybdate mixture causes a sudden change in the strain of Ti3C2Tx, which leads to an interesting “nanoroll” like hierarchical structure. After annealing at H2/Ar atmosphere, vertically aligned molybdenum sulfide (MoS2) crystallites are in situ formed in and on the nanoroll like Ti3C2Tx. Notably, this hierarchical MoS2/Ti3C2Tx hybrid exhibits excellent HER catalytic activity with a small onset overpotential of 30 mV, and a more than 25-fold increase in the exchange current density compared with MoS2 was observed.

Hierarchical “nanoroll” like MoS2/Ti3C2Tx hybrid with high electrocatalytic hydrogen evolution activity

(0D/3D) MoS2 on porous graphene as catalysts for enhanced electrochemical hydrogen evolution

CoP nanoparticles combined with WS2 nanosheets as efficient electrocatalytic hydrogen evolution reaction catalyst

Exfoliated MoS2 with porous graphene nanosheets for enhanced electrochemical hydrogen evolution

A Cu2O/g-C3N4/WS2 triple-layer photocathode was fabricated by using a layer-by-layer assembly method for photoelectrochemical hydrogen evolution. Cu2O was electrodeposited on the FTO as the active layer for light harvesting. The chemically inert g-C3N4 can protect the unstable Cu2O layer and form a p-n junction with Cu2O to increase the light-to-electricity conversion efficiency. Mixed-phase WS2 nanosheets were obtained through a lithium insertion method and used as an effective hydrogen evolution catalyst for photocurrent-to-hydrogen conversion. This photocathode is effective for photoelectrochemical hydrogen evolution, and a photocurrent of −9.5 mA cm−2 at −0.55 V versus RHE (pH 6.0) can be obtained under visible light (λ≥420 nm, 100 mW cm−2).

Yizhe Liu

Papers

Hierarchical “nanoroll” like MoS2/Ti3C2Tx hybrid with high electrocatalytic hydrogen evolution activity

(0D/3D) MoS2 on porous graphene as catalysts for enhanced electrochemical hydrogen evolution

CoP nanoparticles combined with WS2 nanosheets as efficient electrocatalytic hydrogen evolution reaction catalyst

Exfoliated MoS2 with porous graphene nanosheets for enhanced electrochemical hydrogen evolution

Fabrication of a Cu2O/g‐C3N4/WS2 Triple‐Layer Photocathode for Photoelectrochemical Hydrogen Evolution