Vertical III-V nanowire (NW) arrays are promising candidates for infrared (IR) photodetection applications. Generally, NWs with large diameters are required for efficient absorption in the IR range. However, increasing the NW diameter results in a loss of spectral selectivity and an enhancement in the photodetector dark current. Here, we propose a nanophotonic engineering approach to achieving spectrally-selective light absorption while minimizing the volume of the absorbing medium. Based on simulations performed using rigorous coupled-wave analysis (RCWA) techniques, we demonstrate dramatic tunability of the short-wavelength infrared (SWIR) light absorption properties of InAs NWs with base segments embedded in a reflective backside Au layer and with partial GaAs0.1Sb0.9shell segment coverage. Use of a backside reflector results in the generation of a delocalized evanescent field around the NW core segment that can be selectively captured by the partially encapsulating GaAs0.1Sb0.9shell layer. By adjusting the core and shell dimensions, unity absorption can be selectively achieved in the 2 to 3
Fe‐based catalysts are an active, selective, and low‐cost option for tuning Fischer‐Tropsch synthesis (FTS) selectivity toward desirable light olefins. By encapsulating Fe within ZSM‐5, the resultant core‐shell catalysts have the potential to control the product distribution via secondary reactions that occur over the acid sites of the zeolite shell. In this paper, Fe is encapsulated within ZSM‐5 via the seed‐directed growth technique and characterized with a suite of analytical techniques including Mössbauer spectroscopy and X‐ray absorption fine structure (XAFS). Characterization of the core‐shell catalysts indicates that some of the Fe‐based active phase is destabilized during seed‐directed growth, demonstrating the challenges associated with encapsulating an Fe‐based active phase within zeolites. However, comparing FTS performance of the core‐shell catalyst with the Fe‐based control synthesized via incipient wetness impregnation demonstrates improved selectivity toward the desired C2‐C4olefins and C5+hydrocarbons.
more » « less- Award ID(s):
- 1954480
- NSF-PAR ID:
- 10373405
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- ChemCatChem
- Volume:
- 14
- Issue:
- 19
- ISSN:
- 1867-3880
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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