About

Tobias Hanrath is a professor in the R.F. Smith School of Chemical and Biomolecular Engineering at Cornell University, with additional affiliations in Material Science and Engineering, Mechanical Engineering, and Sustainable Energy. He received his B.S. from the University of Tulsa in 2000, his M.S. from the University of Texas at Austin in 2002, and his Ph.D. from the same institution in 2004. His postdoctoral research includes positions at MIT and TU Eindhoven before joining Cornell. His research focuses on the fundamental study of optoelectronic properties of semiconductor nanocrystals, exploring their potential in next-generation energy technologies such as solar energy conversion and energy storage devices. His work leverages the quantum confinement effect in nanocrystals to engineer material properties through adjustments in size, shape, composition, and surface chemistry, providing both technological applications and fundamental insights into quantum mechanics. He is dedicated to integrating research with education, modernizing undergraduate curricula, and engaging students in energy issues through educational outreach and projects.

Research topics

• Materials science
• Composite material
• Nanotechnology
• Computer Science
• Physics
• Crystallography
• Chemistry
• Quantum mechanics

Selected publications

• Spikes Effect: Decoding and Redesigning Pulsed Electrochemical CO₂ Reduction for Enhanced C–C Coupling on Oxide-Derived Copper

  ACS Catalysis · 2025-09-25 · 6 citations

  articleOpen access
  PublisherDOI

• Teaching chemical product design

  Education for Chemical Engineers · 2025-06-02

  articleOpen access

  The CACHE Design Task Force has conducted a comprehensive, year-long study on the teaching of chemical product design across global chemical engineering programs. This paper reviews existing literature and highlights distinctions between product and process design, emphasizing the predominance of process design education in universities. Drawing from co-author contributions and responses to a widely distributed questionnaire, we present recent teaching methodologies for chemical product design. The paper discusses trends in chemical engineering diversification and the gradual inclusion of diverse applications in curricula. It concludes with a call to action for chemical engineering educators to integrate well-established product design strategies into undergraduate programs and reflects on insights shared during the 2024 FOCAPD Conference. • Results of a 1-year study of the teaching of chemical product design worldwide. • Distinctions between teaching product and process design. • Current practice and motivation to teach process design at most universities. • Industrial practices in carrying out product design. • Challenges of merging product design strategies into the ChE undergraduate curriculum.

  PublisherDOI

• Spatially resolved charge-transfer kinetics at the quantum dot–microbe interface using fluorescence lifetime imaging microscopy

  Proceedings of the National Academy of Sciences · 2025-03-17 · 8 citations

  articleOpen accessSenior authorCorresponding

  Integrating the optoelectronic properties of quantum dots (QDs) with biological enzymatic systems to form microbe-semiconductor biohybrids offers promising prospects for both solar-to-chemical conversion and light-modulated biochemical processes. Developing these nano–bio hybrid systems necessitates a deep understanding of charge-transfer dynamics at the nano–bio interface. Photoexcited carrier transfer from QDs to microbes is driven by complex interactions, with emerging insights into the relevant thermodynamic and kinetic factors. The heterogeneities of both microbes and QD ensembles pose significant challenges in mechanistic understanding, which is critical for designing advanced nano–bio hybrids. We used fluorescence lifetime imaging microscopy to analyze charge transfer between a CdSe QD film and Shewanella oneidensis microbes. We correlated the spatiotemporal fluorescence data with an analytical model. Our analysis revealed two distinct distributions of QD de-excitation pathways. The characteristics of these distributions: 1) a faster transfer rate ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:msub> <mml:mover accent="true"> <mml:mi>k</mml:mi> <mml:mo stretchy="false">¯</mml:mo> </mml:mover> <mml:mrow> <mml:mi>E</mml:mi> <mml:mi>T</mml:mi> <mml:mn>1</mml:mn> </mml:mrow> </mml:msub> <mml:mo>=</mml:mo> <mml:mn>1.5</mml:mn> <mml:mo> </mml:mo> <mml:mfenced close=")" open="(" separators=""> <mml:mrow> <mml:msup> <mml:mn>10</mml:mn> <mml:mn>9</mml:mn> </mml:msup> </mml:mrow> </mml:mfenced> <mml:mo> </mml:mo> <mml:msup> <mml:mi mathvariant="normal">s</mml:mi> <mml:mrow> <mml:mo>-</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:msup> </mml:math> ), with a lower acceptor number ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mrow> <mml:msub> <mml:mover accent="true"> <mml:mrow> <mml:mi>N</mml:mi> </mml:mrow> <mml:mrow> <mml:mo stretchy="false">¯</mml:mo> </mml:mrow> </mml:mover> <mml:mrow> <mml:mi>a</mml:mi> <mml:mn>1</mml:mn> </mml:mrow> </mml:msub> <mml:mo>=</mml:mo> <mml:mn>0.03</mml:mn> </mml:mrow> </mml:math> ) and 2) a slower transfer rate ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:msub> <mml:mover accent="true"> <mml:mi>k</mml:mi> <mml:mo stretchy="false">¯</mml:mo> </mml:mover> <mml:mrow> <mml:mi>E</mml:mi> <mml:mi>T</mml:mi> <mml:mn>2</mml:mn> </mml:mrow> </mml:msub> <mml:mo>=</mml:mo> <mml:mn>4.1</mml:mn> <mml:mo> </mml:mo> <mml:mfenced close=")" open="(" separators=""> <mml:mrow> <mml:msup> <mml:mn>10</mml:mn> <mml:mn>8</mml:mn> </mml:msup> </mml:mrow> </mml:mfenced> <mml:mo> </mml:mo> <mml:msup> <mml:mi mathvariant="normal">s</mml:mi> <mml:mrow> <mml:mo>-</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:msup> </mml:math> ) with a higher acceptor number ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mrow> <mml:msub> <mml:mover accent="true"> <mml:mrow> <mml:mi>N</mml:mi> </mml:mrow> <mml:mrow> <mml:mo stretchy="false">¯</mml:mo> </mml:mrow> </mml:mover> <mml:mrow> <mml:mi>a</mml:mi> <mml:mn>2</mml:mn> </mml:mrow> </mml:msub> <mml:mo>=</mml:mo> <mml:mn>0.18</mml:mn> </mml:mrow> </mml:math> ). We assign these distributions to the indirect and direct electron transfer mechanisms, respectively. Our findings demonstrate how spectroscopic imaging can uncover fundamental electron transfer mechanisms at complex interfaces, offering valuable design principles for future nano–bio hybrids.

  PublisherDOI

• Pulsing the Applied Potential in Electrochemical CO₂ Reduction Enhances the C₂ Activity by Modulating the Dynamic Competitive Binding of *CO and *H

  ACS Catalysis · 2024-01-03 · 27 citations

  articleSenior authorCorresponding

  We explore dynamic electrocatalysis by pulsing the applied potential to modulate the temporal microenvironment during the electrochemical reduction of CO2. We focus on copper electrodes by virtue of their unique ability to bind *CO intermediates and enable C–C coupling to form high-value C2 products, such as ethylene or ethanol. We examine the well-known competition between *CO and *H for active sites, as their relative coverage is crucial for enhancing the formation of C2 products. We found that pulsing the applied potential can significantly enhance the electrocatalytic activity of C–C coupling, increasing the turnover frequency of C2 products by up to 33-fold compared to potentiostatic electrolysis. We interpret this improvement in the context of oscillating surface coverage and the transient dynamics of the *CO/*H coverage during the cathodic pulse. Through a combination of experimental and computational methods, we investigate how pulse frequency influences the turnover frequency of CO2 to C2 products on Cu. Our study not only validates recent theoretical predictions about the potential of dynamic (electro)catalysis to surpass the limitations imposed by the Sabatier limit but also uncovers scientific and mechanistic insights into dynamic processes within the electrical double layer. These insights are instrumental in formulating design principles for pulsed CO2 electrolysis with enhanced C2 activity. The outcomes of this study lay a foundational framework for future advances in programmable CO2 electrolysis with improved activity, selectivity, and durability.

  PublisherDOI

• Methods of nanomanufacturing at fluid interfaces and systems for same

  OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information) · 2024-04-19

  articleOpen access1st authorCorresponding

  Methods of nanomanufacturing based on continuous additive nanomanufacturing at fluid interfaces (CANFI). This approach is a fabrication technique that involves, for example, photocuring or “printing” self-assembled layers. CANFI presents a fabrication capability with significant transformative potential improve (i) the spatial resolution, (ii) the speed, and (iii) the range of material compositions that can be printed. Various articles of manufacture can be made using the methods.

  PublisherOA PDF

• Chiroptical Strain Sensors from Electrospun Cadmium Sulfide Quantum-Dot Fibers

  ACS Applied Materials & Interfaces · 2024 · 8 citations

  • Materials science
  • Nanotechnology
  • Composite material

  Controllable synthesis of homochiral nano/micromaterials has been a constant challenge for fabricating various stimuli-responsive chiral sensors. To provide an avenue to this goal, we report electrospinning as a simple and economical strategy to form continuous homochiral microfibers with strain-sensitive chiroptical properties. First, electrospun homochiral microfibers from self-assembled cadmium sulfide (CdS) quantum dot magic-sized clusters (MSCs) are produced. Highly sensitive and reversible strain sensors are then fabricated by embedding these chiroptically active fibers into elastomeric films. The chiroptical response on stretching is indicated quantitatively as reversible changes in magnitude, spectral position (wavelength), and sign in circular dichroism (CD) and linear dichroism (LD) signals and qualitatively as a prominent change in the birefringence features under cross-polarizers. The observed periodic twisted helical fibrils at the surface of fibers provide insights into the origin of the fibers' chirality. The measurable shifts in CD and LD are caused by elastic deformations of these helical fibrillar structures of the fiber. To elucidate the origin of these chiroptical properties, we used field emission-electron microscopy (FE-SEM), atomic force microscopy (AFM), synchrotron X-ray analysis, polarized optical microscopy, as well as measurements to isolate the true CD, and contributions from photoelastic modulators (PEM) and LD. Our findings thus offer a promising strategy to fabricate chiroptical strain-sensing devices with multiple measurables/observables using electric-field-assisted spinning of homochiral nano/microfibers.

  PublisherOA PDFDOI

• Dimensionality control in mesoporous silica: from 0D to 3D materials

  HAL (Le Centre pour la Communication Scientifique Directe) · 2024-09-01

  articleSenior author

  International audience

  Publisher

• Single-cell multimodal imaging uncovers energy conversion pathways in biohybrids

  Nature Chemistry · 2023-07-27 · 34 citations

  articleOpen access
  PublisherOA PDFDOI

• Fabricating Single Crystal Quantum Dot Solids

  2023-03-14

  reportOpen access1st authorCorresponding

  The central goal of this research program was to establish fundamental synthesis and processing principles to enable the fabrication of single crystal quantum dot solids (QDS) with programmable structure (i.e., hexagonal and square) and composition. Our approach towards that goal leveraged access to and experience with unique in-situ, multi-probe characterization techniques to understand and ultimately control the fundamental relationship between processing conditions and nucleation and growth of QDS. The program integrated synthesis and fabrication (Hanrath) with in-situ TEM analysis (Kourkoutis) and computational modeling (Clancy) to gain atomic-level insights into the underlying physical phenomena governing assembly and attachment and to guide the development of optimized processing methods. We have established a foundational understanding of physicochemical interactions of self-assembly at a fluid interface, superlattice structure transformation pathways, the critical role of disorder during the initial dimerization of colloidal quantum dot monomers, and the residual strain distribution within the inter-dot epitaxial bridge which hampers the formation of novel electronics states of the quantum dot solids. Collectively, these insights have contributed towards advancing the mechanistic understanding of the complex choreography of assembly and attachment as well as understanding what currently limits further advances in high-fidelity quantum dot solids and tiles.

  PublisherOA PDFDOI

• Multimodal single-Cell/ Particle imaging and engineering for energy conversion in bacteria (Final Technical Report)

  2023-06-28

  reportOpen access

  Hybrid inorganic-microbial systems have emerged as a potentially transformative approach to combine the light-harvesting capability of inorganic semiconductors and the ability of microbes to orchestrate complex chemical transformations. The objective of this collaborative research is to combine quantum materials synthesis, bacterial synthetic biology, and multimodal single-entity imaging to quantitatively study how hybrid QD-bacteria systems convert light to value chemicals at the single-to-sub cell level, with the ultimate goal of gaining insights to guide the engineering of QDs and bacterial genetics for more efficient bioenergy conversion. The final technical report summarizes our achievements toward this objective.

  PublisherOA PDFDOI

Recent grants

• I-Corps: Light patternable mesoporous material

  NSF · $50k · 2019–2020

• Inorganic Distributed Nanocrystal Heterojuntion Solar Cells

  NSF · $300k · 2008–2012

• Interfacial directed assembly and attachment of interconnected nanoparticle networks

  NSF · $375k · 2018–2022

• Integrating Directed Assembly and 3D Printing to Enable Advanced Nanomanufacturing Across Multiple Length Scales

  NSF · $250k · 2016–2019

• CAREER: Creating Confined-but-Coupled Nanostructures to Balance Quantum Confinement and Quantum Coupling

  NSF · $463k · 2011–2017

Frequent coauthors

• Brian A. Korgel

  The University of Texas at Austin

  31 shared

• Kaifu Bian

  Sandia National Laboratories

  25 shared

• Lena F. Kourkoutis

  Cornell University

  24 shared

• Frank W. Wise

  20 shared

• Joshua J. Choi

  McCormick (United States)

  18 shared

• Kevin Whitham

  Lawrence Berkeley National Laboratory

  18 shared

• Detlef‐M. Smilgies

  Cornell University

  15 shared

• Benjamin H. Savitzky

  Lawrence Berkeley National Laboratory

  14 shared

Education

• PHD, Chemical Engineering

  UT Austin

  2005