An official website of the United States government
The molecular modification of semiconductors has applications in energy conversion and storage, including solar fuels production. We have developed a synthetic methodology using surface-grafted polymers with discrete chemical recognition sites for assembling human-engineered catalysts in three-dimensional environments, providing additional control over the redox properties and stability of the composite material. This presentation will highlight the versatility of polymeric coatings to interface cobalt-containing catalysts with semiconductors for solar fuel production. Spectroscopic techniques, including ellipsometry, grazing angle attenuated total reflection Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy, provide detailed information on the structure and composition of the assemblies at the nano and meso scales. Photoelectrochemical measurements confirm the hybrid photocathode uses solar energy to power reductive fuel-forming transformations in aqueous solutions without the use of organic acids, sacrificial chemical reductants, or electrochemical forward biasing.
more »
« less
Molecular Surface Coatings for Semiconductor Photoelectrochemistry and Photocatalysis
Catalysts accelerate chemical transformations, but the ability to effectively interface them with surfaces for driving industrially relevant reactions using electricity or sunlight as a power source remains a major challenge. This presentation will report on recent efforts from our research group aimed at developing molecular surface coatings for photoactivating chemical transformations that include capturing, converting, and storing solar energy as a fuel. Addressing this obstacle improves fundamental understanding of catalysis in complex environments and enables technological advancements that depend on the precise control and selectivity of nanoscale components. By designing extended environments for the coordination of molecular catalysts, key features of biological enzymes such as extended ligation spheres, channels for substrate delivery and product removal, as well as regeneration strategies can be integrated with the design and synthesis of human-engineered catalysts. Functionality of these hybrid materials for applications in semiconductor photoelectrochemistry and photocatalysis are examined using electrochemical characterization techniques and an improved understanding of structure and function relationships is achieved using surface-sensitive characterization methods, including grazing angle Fourier transform infrared and X-ray photoelectron spectroscopies.
more »
« less
- Award ID(s):
- 1653982
- PAR ID:
- 10048601
- Date Published:
- Journal Name:
- ACS 253rd National Meeting & Exposition
- Page Range / eLocation ID:
- CATL-215
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Catalysts are central to energy conversion in biology and technology; they provide low-energy pathways for steering chemical transformations and are used in applications ranging from manufacturing fuels and fine chemicals to controlling the bioenergetic reactions essential to all living organisms. Accordingly, the study of homogeneous molecular catalysts, including porphyrins, has provided researchers significant insights regarding the mechanisms and structure−function relationships governing myriad catalytic processes, as well as design principles for further improving the performance of human-engineered catalysts. Our research group has recently reported on the favorable catalytic properties of piextended porphyrins for hydrogen evolution, demonstrating the promise of extended macrocycles as a design element and structural motif for preparing electrocatalysts. The pi-extended architecture provides an alternative strategy, compared to using electron-withdrawing or electron-donating functional groups, for adjusting the redox properties of a molecular catalyst and thus a promising avenue for catalyst design warranting further analysis.more » « less
-
Hybrid materials capable of linking light capture and conversion technologies with the ability to drive reductive chemical transformations are attractive as components in photoelectrosynthetic cells. [1] We have recently reported methods of applying molecular surface coatings composed of metalloporphyrin redox catalysts onto solid-state substrates that are either conductive or semi-conductive. [2-5] The metalloporphyrin catalysts used in this work are capable of activating electrochemical transformations including the conversion of protons to hydrogen and carbon dioxide to carbon monoxide. In one approach, metalloporphyrin precursors are prepared via a novel synthetic strategy to yield a macrocycle with a pendent 4-vinylphenyl surface attachment group at the beta-position of the porphyrin ring structure. [2] This modification allows use of a photo-induced immobilization chemistry to attach intact metalloporphyrins to a range of (semi)conducting surfaces. In addition, we have shown that initial application of thin-film polymer surface coatings can provide a molecular interface for assembling metalloporphyrin catalysts in a subsequent wet chemical treatment step. [3] In this presentation, spectroscopic characterization of these materials coupled with electrochemical analysis will be presented. These findings offer an improved understanding of the structure and function relationships governing this class of materials. 1. A. M. Beiler, D. Khusnutdinova, S. I. Jacob, G. F. Moore, Ind. & Eng. Chem. Research, 55, 5306-5314 (2016); DOI: 10.1021/acs.iecr.6b00478 2. D. Khusnutdinova, A. M. Beiler, B. L. Wadsworth, S. I. Jacob, G. F. Moore, Chem. Sci., 8, 253-259 (2017); DOI: 10.1039/c6sc02664h 3. A. M. Beiler, D. Khusnutdinova, B. L. Wadsworth, G. F. Moore, Inorg. Chem., 56, 12178 (2017); DOI: 10.1021/acs.inorgchem.7b01509 4. A. M. Beiler, D. Khusnutdinova, S. I. Jacob, G. F. Moore, ACS Appl. Mater. Interfaces, 8, 10038-10043 (2016); DOI: 10.1021/acsami.6b01557 5. B. L. Wadsworth, A. M. Beiler, D. Khusnutdinova, S. I. Jacob, G. F. Moore, ACS Catal. 6, 8048-8057 (2016); DOI: 10.1021/acscatal.6b02194more » « less
-
Abstract Black phosphorus (bP) is a two‐dimensional van der Waals material unique in its potential to serve as a support for single‐site catalysts due to its similarity to molecular phosphines, ligands quintessential in homogeneous catalysis. However, there is a scarcity of synthetic methods to install single metal centers on the bP lattice. Here, we demonstrate the functionalization of bP nanosheets with molecular Re and Mo complexes. A suite of characterization techniques, including infrared, X‐ray photoelectron and X‐ray absorption spectroscopy as well as scanning transmission electron microscopy corroborate that the functionalized nanosheets contain a high density of discrete metal centers directly bound to the bP surface. Moreover, the supported metal centers are chemically accessible and can undergo ligand exchange transformations without detaching from the surface. The steric and electronic properties of bP as a ligand are estimated with respect to molecular phosphines. Sterically, bP resembles tri(tolyl)phosphine when monodentate to a metal center, and bis(diphenylphosphino)propane when bidentate, whereas electronically bP is a σ‐donor as strong as a trialkyl phosphine. This work is foundational in elucidating the nature of black phosphorus as a ligand and underscores the viability of using bP as a basis for single‐site catalysts.more » « less
-
Catalysis plays a significant role in most processes of the chemical industry, especially in the emerging areas of sustainable energy and clean environment. A major challenge is the design of catalysts with the desired synergies in terms of activity, selectivity, stability, and cost. New insights into many fundamental questions related to the challenge have sparked a surge of interest in recent years in the area of exploring copper-based alloy catalysts. In this review, the most recent progress in the explorations of copper-alloy catalysts will be highlighted, with a focus on the structural and mechanistic characterizations of the catalysts in different catalytic reactions. The fundamental understanding of the detailed catalytic synergies of the catalysts for the targeted heterogeneous catalytic reactions depends strongly on the utilization of various analytical techniques for the characterization. Significant progress has been made in utilizing advanced techniques, both ex situ and in situ / operando characterizations, demonstrating the abilities to gain atomic/molecular level insights into the morphological, structural, electronic and catalytic properties of copper alloy catalysts, especially the dynamic surface active sites under the reaction conditions or during the catalytic processes. The focus on structural characterization in this review serves as a forum for discussions on structural and mechanistic details, which should provide useful information for identifying challenges and opportunities in future research and development of copper-alloy catalysts.more » « less
- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Conference Paper:
- The DOI is not currently available.
