Bottom-up synthesis of high surface area mesoporous crystalline silicon and evaluation of its hydrogen evolution performance

Dai, Fang; Zai, Jiantao; Yi, Ran; Gordin, Mikhail L.; Sohn, Hiesang; Chen, Shuru; Wang, Donghai

doi:10.1038/ncomms4605

Cited by 229 publications

(200 citation statements)

References 71 publications

(94 reference statements)

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“…30 In addition, because the crystallinity of SiNS-650 was higher than the crystallinity of the SiNPs (as shown in Figure 2d), a greater number of the photoderived electron-hole pairs were generated in the former case, with their separation and migration also being easier, owing to the lower R ct value. 11 In general, the R ct value of a catalyst depends on the state of the catalyst. Low crystallinity and the presence of a large number of defect sites inhibit electron transfer and facilitate the recombination of the photogenerated electron-hole pairs.…”

Section: Discussionmentioning

confidence: 99%

“…Silicon dioxide layers reduce the performance by blocking photo-generated carrier transfer from the photocatalyst to the electron accepter. Meanwhile, Dai et al 11 synthesized nanosized mesoporous crystalline Si powders using an unconventional approach, namely, the bottom-up selftemplating method. These mesoporous crystalline Si powders showed an extremely high hydrogen evolution reaction (HER) activity in both a KOH etching system (1.33 mol H 2 per s per mol Si) and a solar water reduction system with methanol sacrificial reagent (882 μmol H 2 per h per g Si) under a 300 W xenon light.…”

Section: Introductionmentioning

confidence: 99%

“…These mesoporous crystalline Si powders showed an extremely high hydrogen evolution reaction (HER) activity in both a KOH etching system (1.33 mol H 2 per s per mol Si) and a solar water reduction system with methanol sacrificial reagent (882 μmol H 2 per h per g Si) under a 300 W xenon light. 11 Among the various nanostructured Si materials available, two-dimensional (2D) Si nanosheets (SiNSs) are desirable as a photocatalyst for the hydrogen evolution reaction based on several advantages such as high surface area, facile accessibility of water molecules and compatibility with other exceptional 2D supports or cocatalysts.…”

Section: Introductionmentioning

confidence: 99%

“…[11][12][13][14] For instance, Okamoto et al 11,12 demonstrated that organosilicon (Si 6 H 4 Ph 2 ) nanosheets can be fabricated by the chemical reaction of polysilane (Si 6 H 6 ) and a Grignard reagent. This method is useful for forming regularly stacked structures of SiNSs with limited dimensions.…”

Section: Introductionmentioning

confidence: 99%

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All-in-one synthesis of mesoporous silicon nanosheets from natural clay and their applicability to hydrogen evolution

et al. 2016

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Silicon nanosheets have attracted much attention owing to their novel electronic and optical properties and compatibility with existing silicon technology. However, a cost-effective and scalable technique for synthesizing these nanosheets remains elusive. Here, we report a novel strategy for producing silicon nanosheets on a large scale through the simultaneous molten-salt-induced exfoliation and chemical reduction of natural clay. The silicon nanosheets thus synthesized have a high surface area, are ultrathin (~5 nm) and contain mesoporous structures derived from the oxygen vacancies in the clay. These advantages make the nanosheets a highly suitable photocatalyst with an exceptionally high activity for the generation of hydrogen from a water-methanol mixture. Further, when the silicon nanosheets are combined with platinum as a cocatalyst, they exhibit high activity in KOH (15.83 mmol H 2 per s per mol Si) and excellent photocatalytic activity with respect to the evolution of hydrogen from a water-methanol mixture (723 μmol H 2 per h per g Si).

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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All-in-one synthesis of mesoporous silicon nanosheets from natural clay and their applicability to hydrogen evolution

et al. 2016

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“…Mesoporous crystalline Si has shown better photocatalytic activity for hydrogen evolution than commercially available silicon nanopowder 78 (FIG. 3d,e).…”

Section: Solar Cellsmentioning

confidence: 99%

Mesoporous materials for energy conversion and storage devices

2016

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At present, more than 80% of the energy consumed globally is derived from non-renewable fossil fuels such as coal, oil and natural gas. The combustion of these fuels inevitably leads to the emission of CO 2 -a main driver of climate change and other serious environmental effects, including the emission of other dangerous gases. Although mitigating climate change is a multifaceted challenge, one of the pillars of any future low-carbon economy will be a substantially increased dependence on renewable and environmentally friendly energy sources and storage systems. Tremendous progress is being made in developing advanced technologies to meet these challenges. However, to enable the cost-effective, large-scale production of these technologies, further improvement of performance and efficiency is needed. Although unique challenges exist for each technology, the development of functional materials is crucial.Porous solids -in particular, mesoporous solids -are appealing materials in many energy applications owing to their ability to absorb and interact with guest species (including, but not limited to, lithium ions, hydrogen atoms and sulfur molecules) on their outer and inner surfaces, and in the pore spaces 1,2 . According to the International Union of Pure and Applied Chemistry (IUPAC) definition, porous materials are classified into three categories according to their pore sizes: micro porous (<2 nm), mesoporous (2-50 nm) or macro porous (>50 nm). Since the first report of mesoporous silica in the 1990s 3,4 , the variety of mesoporous materials available has rapidly expanded, encompassing a very broad range of compositions.Mesoporous materials have exceptional properties, including ultrahigh surface areas, large pore volumes, tunable pore sizes and shapes, and also exhibit nanoscale effects in their mesochannels and on their pore walls. These features are particularly advantageous for applications in energy conversion and storage [5][6][7][8][9][10] . In principle, high surface areas should provide a large number of reaction or interaction sites for surface or interface-related processes such as adsorption, separation, catalysis and energy storage; however, a high surface area does not necessarily translate to an improved performance in applications. Large pore volumes have shown promise in the loading of guest species and in the accommodation of the expansion and strain relaxation during repeated electrochemical energy storage processes. Uniform and tunable mesopore channels facilitate the transport of atoms, ions and large molecules through the bulk of the material, thereby increasing the number of active sites with high accessibility and overcoming the size restriction encountered with microporous materials. In addition, there are fascinating nanoconfinement effects in the voids of uniform mesochannels, which are advantageous in catalysis and energy storage. 3D nanometre-sized frameworks can produce extraordinary nanoscale effects (that is, surface and quantum effects) that result in mesoporous materials with u...

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The Fabrication and Characterization of Bimodal Nanoporous Si with Retained Mg through Dealloying

Balk

2017

Adv Eng Mater

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The fabrication and characterization of bimodal nanoporous silicon films with retained magnesium, achieved through a novel approach utilizing free corrosion dealloying of precursor Si-Mg films in distilled water, is studied. Investigation of film structure and chemical composition using various techniques reveals important characteristics potentially relevant to lithium-ion battery applications. Dealloying of precursor films results in a hierarchal structure, where larger ligaments have an average width of 83 nm and smaller ligaments an average width of 19 nm. A thin, porous surface layer is present on most dealloyed films and is largely composed of magnesium and silicon oxides, as verified by XPS surface analysis. TEM studies reveal that as-dealloyed films are amorphous, but nanocrystalline silicon grains form after vacuum annealing at 500 C. EDS mapping and XPS reveal three distinct chemical composition regions through the film thickness, where residual magnesium generally increases as a function of film thickness, with the highest amount of retained magnesium at the surface. The ligament size, composition, and structure, combined with the simple, non-hazardous nature of the dealloying method, make this an attractive material and processing technique for efficient and scalable production of lithium-ion battery anode material.

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Bottom-up synthesis of high surface area mesoporous crystalline silicon and evaluation of its hydrogen evolution performance

Cited by 229 publications

References 71 publications

All-in-one synthesis of mesoporous silicon nanosheets from natural clay and their applicability to hydrogen evolution

All-in-one synthesis of mesoporous silicon nanosheets from natural clay and their applicability to hydrogen evolution

Mesoporous materials for energy conversion and storage devices

The Fabrication and Characterization of Bimodal Nanoporous Si with Retained Mg through Dealloying

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