Efficient Visible-light Hydrogen Evolution Research Articles

Efficient Visible Light Hydrogen Evolution Catalyst Composed of Non-noble Metal Nitride (Ni3N) Cocatalyst and Zn0.5Cd0.5S Solid Solution

Efficient Visible Light Hydrogen Evolution Catalyst Composed of Non-noble Metal Nitride (Ni3N) Cocatalyst and Zn0.5Cd0.5S Solid Solution

Controlled photoinduced electron transfer from g-C3N4 to CuCdCe-LDH for efficient visible light hydrogen evolution reaction

Ample visible-light response and efficient charge transfers in semiconductor heterojunction are still enslaved to the limited photocatalytic water splitting. In most cases, the rational design of hybrid composites tune in atomic level interaction led to remarkable stability and superior activity. Here, this work is a systematic investigation of metal ion substitution in the LDH and LDH/g-C3N4 hybrid composites for hydrogen evolution reaction (HER) under visible light. The construction of heterostructure not only facilitates the charge separation and transfer owing to the formed heterojunction through band gap engineering and tunable optical properties which are inherited from morphology of as grown CuCdCe-LDH over the exfoliated g-C3N4 but also provides plenty of surface active sites due the increased surface area photostability. The CuCdCe-LDH/g-C3N4 exhibits superior HER rate of 3.5 mmolg−1h−1 with AQY of 5.78% over their binary counterparts. The density functional theory calculations also suggest that the HER activity of CuCdCe-LDH is substantially enhanced by coupling with g-C3N4 the electrochemical results leading to high photocurrent response. The high photocatalytic activity of the composite was due to efficient photoexcited charge transfer process and the synergistic effect between CuCdCe-LDH and g-C3N4. These finding will open scopes for designing inexpensive high performance materials for broad applications of photocatalytic energy conversion.

Triptycene-based discontinuously-conjugated covalent organic polymer photocatalysts for visible-light-driven hydrogen evolution from water

Effective photocatalytic systems that are capable of converting solar energy into chemical fuels have recently attracted significant attention. Covalent organic polymers (COPs) have been explored as promising photocatalysts for visible-light-driven hydrogen evolution from water. Herein, a series of triptycene (TP)-based discontinuously conjugated COP photocatalysts are described for the first-time using TP with monothiophene (MT), trithiophene (TT), dithiophene benzothiadiazole (DTBT), and diphenyl benzothiadiazole (DPBT), denoted as MT-TP, TT-TP, DTBT-TP, and DPBT-TP, respectively. Difference photophysical, morphological, and photocatalytic properties can be tuned by introducing different types of linkers of the TP-based COPs. DPBT-TP shows a significant enhancement of the hydrogen evolution rate (HER) in comparison to those using other polymer photocatalysts at identical conditions. The transmission electron microscopy/scanning electron microscopy data show that the tube-like polymer photocatalysts afford higher HERs than those observed with the particle-like polymer photocatalysts. This report describes the first demonstration that the polymer photocatalysts constructed by the disconuiously conjugated system (conjugation length: less than 5 aromatic rings) is sufficient for an efficient visible-light-driven hydrogen evolution. It provides an alternative material design strategy for polymer photocatalysts to achieve efficient visible light hydrogen evolution.

CoAl-layered double hydroxide nanosheets as an active matrix to anchor an amorphous MoSx catalyst for efficient visible light hydrogen evolution.

CoAl-layered double hydroxide nanosheets (CoAl-NSs) could serve as an active matrix to effectively anchor amorphous MoSx nanoparticles with high dispersion and the formation of an additional active "CoMoS" phase. The resulting CoAl-NSs/MoSx catalyst showed 13 times higher H2 evolution activity than free MoSx nanoparticles from an erythrosin B-triethanolamine (ErB-TEOA) system under visible light.

Dye-sensitized cobalt catalysts for high efficient visible light hydrogen evolution

In this work, high efficient non-noble metal cobalt cocatalysts implanted on the surface of graphene (G) by one-step photoreduction and in-situ chemical deposition methods for hydrogen evolution were reported. XRD and TEM characterizations showed that the Co and CoSx nanoparticles were deposited on the graphene surface as Co/G and CoSx/G composites. CoSx/G and Co/G nanohybrids exhibited high photocatalytic activities for hydrogen evolution sensitized by Eosin Y (EY). The amounts of H2 evolution reached 708.5 and 675.5 μmol over the EY-sensitized CoSx/G and Co/G nanohybrids irradiated under visible light with wavelength longer than 420 nm in 3 h respectively. The apparent quantum efficiency (AQE) of 8.71% over EY-Co/G was accomplished under 520 nm illumination. The fluorescence results indicated that the lifetime of excited electron was remarkably increased. Graphene might promote the photogenerated electrons transfer from excited dye to the hydrogen evolution active sites such as Co or CoSx, and consequently enhance photocatalytic hydrogen evolution efficiency.

Dye-cosensitized graphene/Pt photocatalyst for high efficient visible light hydrogen evolution

In this work, a highly efficient and stable photocatalytic H2 evolution catalyst was constructed on Pt deposited graphene sheets cosensitized by Eosin Y (EY) and Rose Bengal (RB). Under two-beam monochromic light irradiation (520 and 550 nm), a high quantum yield (QY) up to 37.3% has been achieved owing to maximum utilization of incident visible light. As a result of the excellent electron transport properties of graphene, it can greatly facilitate the forward electron transfer from photoexcited dye molecules to Pt catalyst and suppress back electron transfer, which significantly enhances photocatalytic efficiency for H2 evolution. This efficient cosensitization strategy is also effective in enhancing H2 evolution efficiencies of dye sensitized TiO2 and multiwall carbon nanotubes (MWCNTs).