Catalytic and Transport Behaviors of Model and Porous and Composite Nanostructures
- Univ. of New Mexico, Albuquerque, NM (United States); Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
- Univ. of New Mexico, Albuquerque, NM (United States)
As stressed in the Basic Energy Sciences Advisory Committee (BESAC) Report “New Science for a Secure and Sustainable Energy Future” (December 2008), solving our Nation’s energy challenges will entail more than incremental changes in present materials-related technologies; new, advanced routes to nanostructured materials with transformational properties will be required. Herein we describe the design and fabrication of a hybrid biotic/abiotic membrane reactor that, mimicking natural systems, employs the metalloenzyme, carbonic anhydrase, to separate CO2 from N2 with unprecedented purity and rate. The membrane design, synthesis, and operation are based on multiple biomimetic and nanoscale fabrication strategies, nanoscale dimensional features, and nanoscale physical phenomena, for example: 1) Bottom-up self-assembly of a membrane comprising a periodic, aligned, cylindrical nanopore array with 8 nm diameter pores designed to accommodate carbonic anhydrase (CA) enzymes 2) Top-down Atomic Layer Deposition (ALD) and plasma processing of the nanopore array to create 18nm deep (by 8nm in diameter) superhydrophilic pores bounded by hydrophobic/superhydrophobic interfaces 3) Formation of a continuous, defect free, ultra-thin (~18-nm thick) but strong water membrane by capillary condensation within the uniformly-sized, superhydrophilic nanopore array 4) Accommodation of CA within the water filled nanopore array (~2 CAs per hydrophilic pore channel) to achieve an effective CA concentration within the 18-nm thick water membrane over 10X greater than achievable in solution Exposed to a mixture of CO2 and N2 this biomimetic membrane rapidly and selectively dissolves CO2 within the CA filled water nano-channels on the ‘upstream side’ and regenerates CO2 at the superhydrophobic interface on the ‘downstream’ side. In combination, the high CA concentration and exceptionally short diffusion distances enable rapid and highly selective CO2 separation from N2 and H2. Our membrane has a combined CO2 flux and selectivity that exceed by orders of magnitude all existing CO2 membranes and for the first time meet the US Department of Energy guidelines for CO2 sequestration technologies. (The performance of our membrane was recognized by an R&D100 Award and the first R&D100 Green Technology Award in 2015 and an issued US Patent in 2017). We believe this membrane could be employed in combination with sequestration to help reduce greenhouse gas emissions and provide a viable, economically feasible pathway to achieve the goals of the 2016 Paris Accord, which aims to maintain a global temperature rise this century less than 2°C above pre-industrial levels. Further this membrane concept could be adapted to other enzymes to accomplish other separations of interest, e.g. H2. We also have established processing-structure-property relationships of ultrathin membrane-like monolayer materials that are intrinsically catalytic. Establishing processing-structure-property relationships for monolayer materials is crucial for a vast range of applications spanning optics, catalysis, electronics, and energy. Presently, for MoS2, a promising catalyst for artificial photosynthesis, considerable debate surrounds the structure/property relationships of its various allotropes. Using high-resolution transmission electron microscopy supported by density functional theory, we unambiguously solved the structure of MoS2 monolayers and showed lithium intercalation to direct a preferential transformation of the basal plane from 2H (trigonal prismatic) to 1T’ (clustered Mo). These changes alter the energetics of MoS2 interactions with hydrogen ((GH), and, with respect to catalysis, the 1T’ transformation renders the normally inert basal plane amenable towards hydrogen adsorption and H2 evolution achieving Hydrogen Evolution Reaction (HER) catalytic activity comparable to 2H MoS2 edges on Au(111), one of the most active HER catalysts known.
- Research Organization:
- Univ. of New Mexico, Albuquerque, NM (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC)
- DOE Contract Number:
- FG02-02ER15368
- OSTI ID:
- 1371947
- Report Number(s):
- Final Report:DOE-UNM-ER15368
- Country of Publication:
- United States
- Language:
- English
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